Donald F. WILKES: Rolamite

 
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**Donald F. WILKES**

**Rolamite**

---

**The first (or
second, after Bellocq's wave-pump) new mechanical
principle discovered in the 20th century.**

**[Popular
Science (March 1966): "Frictionless Machines from Rollers
& Bands"](#ps)**  **[Popular Mechanics (February 1968): "The
Amazing Rolamite"](#pm)**  **[Mechanical Engineering (April 1968):
"Rolamite: A New Mechanism"](#me)** **[US Patent # 3,452,175 -- Roller-Band
Devices](#usp)** **[US
Patents for Rolamite Devices](#rolamite_patents)**

---

***Popular
Science* (March 1966)**

**"Frictionless Machines from Rollers &
Bands"**   
 by**Harry Walton**

As basic as the
lever or pulley, the simple concept called "Rolamite" promises
a revolution in mechanical design.

What's a Rolamite?
It looks like a simple gadget made with two rollers and a
steel band, but it's much more. As basic as the wheel, the
lever, or the hinge, it is the only elementary machine
discovered this century. Its use will be widespread --- in
everything from switches, thermostats, and valves to pumps and
clutches, and as almost frictionless bearings.

The Rolamite concept
is the invention of Donald F. Wilkes, a Sandia Corp. engineer
who was studying a suspensions system made with a bent elastic
band fastened to opposing surfaces in an S shape. He found
that the center of the loop could be moved horizontally with
amazingly little resistance (To try it, clamp one end of a
steel tape to a table and another section to a ruler held
horizontally above it).

But the band can
provide no positive mechanical action. In a flash of genius,
Wilkes inserted two rollers, large enough to overlap and so
key themselves in, and the Rolamite principle was born. The
rollers may move in a fixed frame or one of the horizontal
frame members may move on the rollers, travel being limited by
the length of the band.

As the rollers are
pushed to the right, for example, they turn in opposite
directions, but are always in rolling contact with the band.
Nothing slides, rubs, or slips; it is always the same points
that come into contact between roller and band. And a rolamite
unit never needs lubrication.

**Prepackaged
Energy**

What about
band-flexing? It would seem that takes energy, creating
friction. But that energy is prepackaged when the band is
installed under tension. Bending of one part of the band is
accompanied by straightening of another, which supplies the
needed energy.

In tests, Rolamite
devices display friction of an amazingly low order --- one to
ten percent of that in the best ball and roller bearings of
similar capacity.

The Rolamite units
closest to production are designed for light loads and such
jobs as opening and closing contacts or valves or performing
mechanical operations. A rolling frame member might carry
control studs, fluidic valves, or printed circuit contacts on
its outer surface.

**Tricks with Bands
& Rollers**

Instead of being
uniform, bands can introduce more or less resistance at some
point of roller travel. Holes of various shapes can be punched
in them to make action easier at a predetermined point and to
a precise degree. Bimetallic elements and springs, even cloth,
plastic, or rubber bands can be used.

Such modification
can produce a snap action, sudden braking, latching, and other
control functions. A sharply bent band can act as a detent.

Rollers can be
fitted with bulges or rubber stops for positive braking. The
rollers can be of different sizes. If one is smaller, it turns
faster than the other and you have a speed-changing device.
Extra rollers may be added, always two at a time. They may be
spool-shaped with a moving table between them. Even square and
triangular rollers are possible.

Fascinated by the
possibilities, Wilkes and other Sandia people have doodles up
Rolamite light switches, fishing reels, vibrationless sanders,
clutches, a greatly improved toilet valve, an odometer, a
reciprocating variable-speed tool drive, and even a
pellet-shooting toy gun. There's no end in sight.

![](1ps1a.jpg)  
 ![](1ps1b.jpg)

Basic rolamite uses
a flexible band of steel or other material curled in an S
shape and forming a freely moving loop. Two rollers are then
inserted and the band is put under tension. Roller cluster
moves along band with amazingly little friction. By making
cuts in bands, roller action can be that of snap-action
switch, a thermostat (when a bimetallic band is used), or any
of at least 50 other devices. It can support a traveling table
for example. Square and triangular rollers are even possible.

---

***Popular
Mechanics* (February 1968)**

**"The Amazing Rolamite --- It Opens the Door
for 1000 Inventions"**

by

**Norman Carlisle**

One night in
September 1966, a lean young, sandy-haired engineer named
Donald Wilkes went into his garage workshop in Albuquerque NM
to try an idea. What came out several hours later has been
hailed as the first truly elementary mechanical invention of
the 20th century.

Dubbed the Rolamite,
it's an almost frictionless bearing with countless
applications in modern devices ranging from toasters to space
vehicles. Engineers say it will take its place alongside the
wheel, lever, and spring as a fundamental discovery of major
significance.

Basically, the
Rolamite consists of two rollers held in a track on opposite
sides of an S-shaped band of springy metal, the rollers glide
effortlessly in the track because the band moves with them as
they roll along. Since the band and rollers are both moving at
the same speed, there is no slip or drag between them and
therefore virtually no friction. The device is so versatile it
can function as a switch, a valve, a pump, a fuse, a
thermostat, a force amplifier, a clutch, a speed changer, a
brake, a pressure-sensing control, a solenoid, a fire alarm a
--- you name it and it'll do it.

How could such a
fundamental principle remain so long undiscovered? That was
the first question I tossed at Donald Wilkes as I interviewed
him recently in his equipment-crammed laboratory at Sandia
Corp., the nuclear weaponry development center that Western
Electric runs for the AEC.

"It's hard to
believe", answered the 37-year-old inventor, who has been an
avid PM reader since he was a boy. "The amazing thing is that
a caveman has all the materials for making a Rolamite. Logs
could have served for rollers and vines for the bands."

So how had Wilkes
come to invent the Rolamite? In the course of his missile work
at Sandia, he had tinkered together a suspension system that
particularly intrigued him. It consisted of a flexible metal
band fastened in an S shape between two parallel surfaces. It
was responsive to movements, all right --- too responsive.
"Wiggly and wobbly", Wilkes describes it.

On that
now-momentous night, Wilkes was relaxing in his living room
when it hit him. How about putting rollers in the curves of
the S? He jumped up and rushed out to his workshop. From his
stock of scrap he fashioned a simple track and inserted a
strip of beryllium copper he'd been carrying around in his
pocket. From these components, he made the first Rolamite.

Now, Wilkes
wondered, what would happen when he tipped the thing so that
the rollers moved? Would the rollers slide along the curves of
the band, or would the band move right along with the rollers
with no slipping? Wilkes knew that if the band slipped he had
nothing.

Again and again
Wilkes tried it, his excitement growing. The rollers moved
smoothly and the band went right with them. There was no
detectable slip. The next morning he hurried to his lab to
machine a more sophisticated model. Sensitive tests confirmed
the observations made with the first crude model. There was no
slipping and, therefore, little friction.

As development work
went on, Wilkes and fellow researchers discovered that an
almost infinite number of variations could be made by changing
the shape, size and structure of the bands, rollers and
tracks. Take the band, for example. So long as it's under the
same tension throughout its length, the rollers are stable at
any point in the track. It takes just as much force to push
them one way as the other way. But if you cut a slot in the
band, you weaken it at that point, creating what is called a
force bias --- the rollers are made to "prefer" a particular
point in the band.

To understand the
effect of a slot in the band, think of the two loops of the S
as springs that each exert a force against the other. Like a
coiled watch spring, the band wants to lie flat and thus
stores energy when it is forced to bend around the rollers.

When one of the
loops is weakened by having a slot cut in it, the other loop
overpowers it and "unwinds", pulling the rollers with it. By
cutting a long, tapered slot in the band, the rollers can be
made to move the entire length of the track under their own
power since the band becomes progressively weaker toward the
widest end of the slot.

In a typical
application, Wilkes visualizes a Rolamite with a slotted band
to lick one common household annoyance --- the leaky toilet
valve. The leakiness usually results from the failure of the
ball float and lever mechanism to generate enough pressure to
close the water-supply valve. The force generated in a slotted
Rolamite lever would close the valve with 30 times the
strength of present valves.

**Rollers can be
Different Sizes**

Wilkes' first
Rolamite used equal-sized rollers, but he soon found that one
roller in a pair could be a giant, 10 or more times bigger
than its companion. With rollers of different sizes, you get a
remarkably simple speed changer that can be used in any number
of mechanisms.

Perhaps the oddest
discovery is that the rollers need not be round. Sandia
researchers have tried triangular, hexagonal, oval and
polygonal rollers. The basic principles of the Rolamite still
apply just as with round rollers. The different shapes of
rollers give the Rolamite many additional functions. For
instance, a rectangular roller can be designed to lodge
against a stop in a braking mechanism.

A lot of variations
are possible in the track, too. For example, a track wider at
one end  makes the Rolamite a powerful force amplifier
--- energy is released when the rollers slip into the wider
portion of the frame. This energy can actuate a variety of
mechanisms, such as a firing pin or a switch.

There are other
advantages, too. Many Rolamited devices would never need a
drop of oil. Then there's smoothness of operation. The steady,
uniform operation of a Rolamite can take the jerks out of
pop-up toasters, power sanders and a host of other devices.

There's cost. Wilkes
estimates that the Rolamite will actually reduce costs in 75%
of its applications. The Rolamite does not require close
tolerances, so they're cheaper to make. Finally, there's the
all-around toughness. Extreme heat, cold or exposure to
weather won't affect Rolamite operation.

But, I wondered,
doesn't all that flexing of the band cause it to wear out
eventually? Doesn't metal fatigue cause it to break? Those
were questions that bothered Sandia engineers too, at the
beginning. Now they've quit worrying. The beryllium copper
bands used in Rolamite have proved to be so sturdy that they
show no sign of metal fatigue after 1,000,000 flexures. At
that rate, the engineers figure, the band in a Rolamited home
light switch operated 10 times a day would last 300 years. A
Rolamited bathroom scale used five times a day would not wear
out in 600 years.

You'll never see the
first applications of Rolamite because they're tucked away in
secret weaponry made by Sandia engineers. But hundreds of
industries are embarking on crash programs to adapt the
Rolamite.

Because Rolamite was
developed with the help of tax dollars, it is available to the
public. The Atomic Energy Commission will grant a royalty-free
license for its manufacture to anyone interested. Wilkes
himself now heads a new company set up to speed the Rolamite
revolution along.

"We've just begun to
scratch the surface", Wilkes says. "Just wait until the
independent inventors get going."

**How the Rolamite
Works**

![](1pm1.jpg)

Basic Rolamite
consists of two rollers in a track with an S-shaped band of
springy metal between them. As the rollers move, the band
unwinds off one and winds onto the other simultaneously.
Because the rollers and band are always traveling together at
the same speed, there is no friction between them and they
move with little effort. The two loops of the S are constantly
fighting each other to unwind and lie flat. So long as the
band is uniformly springy, the loops balance each other and
the rollers remain at rest. When you cut a tapered slot in the
band, the band gets progressively weaker as the slot gets
wider. The portion of band curled around the upper roller is
always stronger than the portion around the lower roller. The
upper loop thus overpowers the lower one and unwinds, pulling
the rollers with it. This is one of a number of ways a
Rolamite can be made to provide motion of its own.

![](1pm2.jpg)![](1pm3a.jpg)![](1pm3b.jpg)

---

***Mechanical
Engineering* (April 1968)**

**Rolamite: A New Mechanism**

**by**

**Donald W.
Wilkes**

**Part 1: Nature of
the Device**

The Rolamite
geometry, developed over the past year by the author, forms a
simple mechanical design element which may, with variations,
be used to advantage in a multitude of applications in place
of traditional elements such as gears, pistons, pumps,
switches, springs, levers, latches, brakes, clutches, and
valves.

**From Basic Idea**

The basic rolamite
geometry, Figure 1, also shown diagrammatically on the next
page, consists of two rollers mounted inside a
parallel-surface channel and held together in a free-rolling
cluster by a flexible band under tension. This arrangement
constrains the rollers to counter-rotate without slipping as
the cluster moves along the channel, thereby providing the
close-couples geometry which can be exploited to perform many
functions.

The two-roller
cluster is free to transverse from left to right, practically
without friction. Surface velocities between the rollers and
the band are equal; hence there is no sliding friction, at
least on a macroscopic scale. Tests on models have shown that
coefficients of friction as low as 0.0005 are achievable. This
is about an order of magnitude better than the best ball or
roller bearings.

**Figure 1:** The
Basic Rolamite Mechanism ~ An S-shaped band of springy metal
(represented by the white strip) is constrained by two guides
and two rollers. The rollers are free to move, the band
winding off one and on onto the other at the same time. The
band itself must be under the other one at the same time. The
band itself must be under tension, thus the ends usually are
permanently fastened in some manner. There is virtually no
friction. Since the band and rollers are moving at the same
speed, and there is no slippage between them, since the band
tension creates a tight wrap-around. Each half of the S tends
to unwind, but since they are balanced the cluster remains at
rest unless an outside force acts on it. This equilibrium can
be disturbed by changing portions of the band (varying width,
thickness, performing, etc.) and the cluster will then move by
itself.

![](1me1.jpg)

**To Sophisticated
Applications**

Out of this basic
arrangement, an almost unlimited variety of mechanical devices
can be developed. Force amplification, detenting mechanisms,
braking and clutching, sequencing, pumping fluids, temperature
sensing, electrical contacts -- the list could go on and on.
There are, however, three distinct areas for its use: (a)
those where the geometry not only forms the heart or essence
of the device, but also provides most of the necessary
additional functions as well; (b) where the geometry forms the
backbone but not the whole mechanism; and (c) where the device
would be used as a separate subcomponent building block for
use in other systems. Table 1 shows applications for these
three areas.

Consideration of the
following attributes may help the designer to realize the
rolamite's possibilities: (a) its low coefficients of
friction, which enable most devices to operate sensitively and
reliably for long periods of time with a minimum of
lubrication; (b) its ability to produce many types of
force-deflection characteristics; (c) its capability of
providing a great many mechanical and electromechanical
functions; (d) its applicability to countless distinct devices
ranging from kitchen appliances to outer space
instrumentation; (e) its adaptability for use in components of
all sizes -- large to microminiature; (f) its simplicity,
which allows the design of complete mechanical and
electromechanical assemblies with very few piece-parts ---
rarely more than 10; (g) its applicability to modern
manufacturing techniques such as chemical etching and
continuous-strip processing; and (i) its relative freedom from
critical manufacturing tolerances.

High-speed set-up or
step-down ratios can be obtained from the rolamite geometry.
High torques can be transmitted without slippage because the
normal forces and tensions can be made relatively large
without introducing severe frictional losses, and normal
bearing reaction friction losses are not present.

Consider the
rolamite inertial odometer (doubly integrating accelerometer)
shown as in Figure 2. This type of device is capable of
inertially measuring up to several miles of vehicle travel in
a single stage and, because of the low coefficients of
friction, doing it very accurately. Most other types of
inertial odometers (such as the spur gear arrangement shown
above as Figure 3) must support the flywheel element or its
equivalent in bearings in the acceleration field, making it
very difficult to keep frictional influences negligible.
However, in the rolamite odometer no friction is added to the
cluster by the vehicle acceleration.

In addition, the
rolamite can accomplish 220-to-1 or 300-to-1 speed step-ups in
a single stage, whereas three stages of spur gearing would be
required.

**Figure 2:**
Rolamite Inertial Odometer ~ By attaching a small rolamite
roller to a large heavily rim-weighted flywheel, the linear
acceleration of the roller centerline can be very small
compared to vehicle acceleration. Since this type of device is
a doubly integrating accelerometer, vehicle displacement is
proportional to cluster displacement. A typical value is 8.5 x
204; thus if the driving roller in the figure move 2 inches,
it would represent a vehicle travel of 2.7 miles (2" x 8.5 x
104). Because of low friction, it can be done very accurately.

![](1me2.jpg)

**Figure 3:**
Conventional Inertial Odometer ~ Here the flywheel is
supported in bearings which, when subjected to acceleration
forces, become friction bound. In order to scale down motion,
many gear stags are needed, further compounding the friction
problem. And accuracy suffers.

![](1me3.jpg)

**The Production
Factor**

The rolamite
geometry forms a mechanical suspension system capable of
achieving substantial reductions in friction in the realm of
extremely low bearing pressures. Devices based on the rolamite
concept may be dramatically simple and easily
microminiaturized, tolerant of production variations, and
inherently capable of a great many of the functions required
in electromechanical devices (Figure 4).

**Figure 4:**
Using the Rolamite Principle

![](0me4.jpg)

Rolamite devices can
produce any type of force-deflection characteristic. Without
adding more parts to a device, it is possible to obtain
constant force levels, positive and negative spring constants,
second order and higher force curves, detenting actions, etc.,
in any desired combination. These forces may be highly
localized or distributed. Reasonably, sharp step functions and
sinusoids are also obtainable.

The negative spring
characteristics obtainable with the rolamite geometry are of
particular interest. In the past the designer has been limited
to the use of permanent magnets, buckling helical springs, and
other rather indirect and imprecise methods, difficult to
analyze and not accurately predictable, to achieve sharp
breakaway or hair-trigger action. With rolamite, negative
spring-constant or other negative force-deflection action can
be achieved in exactly the right way with no additional parts.
This opens up new fields for mechanical amplifiers,
oscillators, and motion detectors, and may permit cheaper
mechanical devices to replace magnets in many applications.

With rolamite the
designer can incorporate the precise amount of viscoeleastic
damping or coulomb friction desired, either continuously or as
a function of displacement; he may directly clutch or brake a
roller or both rollers, or provide overriding action or a
local uncoupling; produce sequencing, extremely high direct
speed or torque changes, maximum-minimum limit-stops,
squeezing, latching, insertion, pullaway action, and
recording.

**The Beauty of the
Band**

It is indeed
fortuitous that the key element in the rolamite geometry is
the band, because, of all the engineering materials, thin
metals are second only to tiny wires ad whiskers in excellence
of mechanical properties, while concurrently they are optimal
for one of the best manufacturing processes available ---
chemical etching. This single element can provide forces,
electrical circuitry, electrical contacting, programmed fluid
resistance, sliding, latching, releasing, differential
detenting, sequencing, maximum-minimum recording, differential
action, sealing, metering, insulating, viscoelasticity,
bimetallic behavior, etc. Although the band profile can be
complex, the chemical-etching process requires only that a few
master patterns be generated. Hence many of the aforesaid
functions are obtainable at a low cost.

The suspension,
bearing, and force features of rolamites are definite
advantages. More important, however, is the versatile way the
rolamite geometry can produce nearly all known mechanical and
electromechanical functions in a wide variety of combinations
using very few piece-parts (usually 4 to 10). This design
versatility and economy stems from the many types of motion
directly obtainable from the cluster, manufacturing tolerance
and adjustability, and the simple, adaptable elements used.
Although the rolamite geometry looks somewhat less promising
for recirculating rotary speed changes and bearings, the
lessons learned from the rolamite geometry relative to tip
guidance, rolling separators, friction control through the
angle of repose, and the value of compliant behavior could
well point the way to greatly improved high speed rotary
devices, ones which could operate without lubrication for long
periods of time and which could be more economically
manufactured than existing devices.

**Part 2:
Engineering**

When the roller
cluster is locked between the guide surfaces by sufficient
band tension, and permitted to roll enough to relive forces
induced by the tensioning process, the roller axes are
perfectly parallel with each other and with the guide
surfaces; therefore, the entire geometry is placed with its
preferred minimum energy state (pure rolling state) because
the tension in the band is at a minimum.

This rolling state
is assured by the laws of flexure so that there need be no
slippage between the band and rollers or between the band and
guide surfaces as the locked geometry is rolled. Since the
band tensions and the elastic strains induced in the band when
it is bent around the rollers are equal and opposite, and
because the rate at which strain energy is entering and
leaving the band area adjacent to each of the rollers is
constant, no net axial force is exhibited by the cluster ---
that is, the cluster is essentially in neutral equilibrium at
any position along the horizontal x-axis within the confines
of the band and the guide surfaces. This balance is
independent of the roller diameter.

**Figure 5:**
Notation Used With basic Rolamite Geometry ~ The band tensions
T acting through distance S set up a force couple which is
balanced by the reaction force couple, N x A. the cluster is
at equilibrium at any position, but free to move.

![](0me5.jpg)

The parameters for
defining the rolamite geometry are shown in Figure 5, where

T = band tension   
 N = normal
reaction force   
 S = spacing
between guide surfaces   
 A = axial
spacing (spacing between roller centerlines) measured parallel
to the guide surfaces   
 Alpha =
repose angle of the cluster   
 Gamma =
contact angle of the cluster   
 T = band
thickness (assumed constant)

The external normal
reaction forces N appear on the cluster at points A and B to
balance out the force couple introduced by the band tension.

**Suspension
Analysis**

*Constraints:*
Constraints are imposed on the geometry for several reasons:
(a) Most commonly, the desire to insure fully elastic behavior
in the band without any plastic deformation; (b) some minimum
endurance limit on the number of cycles the geometry may
undergo; or (c) the limitation of some feature in the locking
cluster geometry. For simplicity, the following analysis is
limited to cases where the band thickness t is constant
throughout the working portion of the band.

In order to insure
fully elastic behavior or some minimum endurance level for the
band, the maximum strain induced by the combined effects of
bending to conform with the roller diameter, and all other
axial strains induced by initial tensioning, induced loadings,
or through Poison's ratio effects due to normal loadings, must
be kept below some maximum level.

(1) *E*\* >
*E*fmax + *E*T + *E*L
+ *Y*EN

Where

*E*\* (Epsilon\*)
= design strain limit   
 Epsilon *E*Fmax
= maximum tensile fiber stress induced by bending around
rollers   
 Epsilon *E*T
= strain induced by tension   
 Epsilon *E*L
= tensile strain induced by loading   
 Epsilon *E*N
= normal compressive strain   
 *Y*
(Gamma) = Poisson's ratio

In most situations,
flexural strains are strongly dominant and if *E*Fmax
is set at about 70% of *E*\*, a safe initial design
estimate will emerge without a detailed consideration of the
other terms until the design is approaching final form, at
which time it will be easy to include approximations of these
other terms.

To further simplify
the following discussion, the assumption will be made that the
band is perfectly flexible, that is, it has not flexural
stiffness. The constraints imposed by the free-rolling locked
cluster are: First, s - 3t (Figure 1) must be greater than the
diameter of the largest roller, or interference will occur.
Mathematically stated, this constraint is:

(2) (s - 3r) > d1

where

d1 > d2

Additionally, (s -
3t) must be smaller than the sum of the roller diameters, or
the cluster will not lock. Thus,

(3) (s - 3t) < (d1
+ d2).

*Static
Equilibrium:* Cluster equilibrium requires that the
moment induced by the nonaligned band tensions T must be
counteracted by an equal and opposite moment induced by normal
forces *N*, as shown in Figure 5. This requirement is
expressed as

(4) *TS = NA*

and

(5) *N/T = S/A*

where

*S* = s - 2 (t
/ 2) = s - t

*Tight Geometry:*
A real band has flexural stiffness, and a real rolamite
arrangement need not be tight in order to present a true
rolling geometry. An infinite tension would be required to
pull a real band into true parallel tangency with a pulley,
which is of course impossible because of the finite ultimate
strength. The rolamite geometry is different because the
moment introduced by band tension may be countered by the
guide surface reactions to give an essentially tight geometry.
An essentially tight geometry occurs when the tangent lines
between the band and the guide surfaces and the band and
rollers fall inside the contact interface area between the
rollers, band and guide. This occurs when the tension is of
the order of

(6) T ~> *EI/tR*'

where

*E* = tensile
modulus of elasticity   
 *I* =
cross-sectional area moment of inertia   
 *T* =
band thickness   
 *R* =
rolling radius

The exact tension
for functionless tightness depends upon the elastic moduli of
the materials involved. While it is usually possible to add
sufficient band tension to produce an essentially tight
geometry, the amount of tension required to do this is usually
too high to allow really sensitive behavior; therefore most
rolamites use geometries which exhibit some degree of
looseness.

**Figures 6 / 7:**
Loose Geometry Parameters ~ The arrangement is very tolerant
of surface roughness, out-of-sound rollers, jamming caused by
particles, and thus requires less manufactured precision.

![](0me6.jpg)![](0me7.jpg)

*Loose Geometry:*
Figures 6 and 7 show a typical loose geometry and define the
parameters used to describe it.

The unsupported
length of the band is inversely proportional to the applied
tensile couple, whereas the normal reaction force is direcly
proportional. A complete analysis exists which permits
prediction of these parameters, given certain initial
conditions, but is too detailed for inclusion in this article
(see reference at beginning of paper).

For the loose
geometry interaction, early all of the equations and analyses
previously presented must be modified or qualified, or at
least applied literally only when acting within certain
limits. First, A\* replaces A in these formulas and represents
the axial distance between two outer contact lines between the
guide surface and band.

The loose geometry
also introduces it the cluster a degree of compliance which
minimizes the effects of surface roughness, permits the
cluster to accommodate minor variations in rollers (such as
out-of-roundness) without balking, allows the cluster to ride
up over particulate contamination without jamming, and in many
ways reduces the criticality and degree of manufacturing
required.

*Rolling Friction:*
Friction coefficients for the rolamite geometry are designed
as the ratio of the frictional force measured at one or the
other roller centerline divided by the normal reaction force
generated by the band tension.

The friction
coefficients measured to date on various loose rolamite
configurations using typical engineering materials without
lubrication and with 0.205-inch to 0.500-inch roller
diameters, have fallen in the range  0.0004 to 0.0016,
with 0.0008 the expected value in...

*[missing pages
18-19 --- under construction]*

**Part 3:
Applications**

Any desired
proportion of the above seemingly paradoxical attributes may
be achieved with a single device.

Rolamite devices can
accommodate significant surface irregularities without
jamming, roll over small foreign particles, and accept minor
imperfections in their own geometry. Abnormally high forces
and torques of unpredictable, infrequent, or sporadic nature
such as may arise in accidents or rarely encountered
environmental situations can be accommodated because of the
band compliance; hence, the geometry is tolerant. However,
after a perturbation has passed, the geometry will
aggressively return to its lowest friction state. A rolamite
suspension can be designed to be very tolerant (soft, flowing,
almost fluid in action), moderately tolerant (but well
controlled), or completely intolerant (uncompromising,
invariable).

*Force
Amplification:* There are many methods of rapidly
extracting kinetic energy which have been imparted to the
roller cluster by internal means such as springs, or by
external means such as acceleration. Most of these methods
permit the attainment of high force levels during the rapid
deceleration of the roller cluster. Some of these methods make
it possible to retain or entrap the high force levels. In
addition, some of the methods tend to minimize, and some tend
to maximize, frictional processes during the deceleration
phase.

**Figure 13:**
Offset Channel Force Amplification results from a change in
geometry which in effect redcues distance A and thus increases
the normal force N. Care must be taken not to make S too large
or the rollers will unlock.

![](0me13.jpg)

Typical methods of
force amplification include the use of various types of
wedging for the rollers and of offset channels. Figure 13
illustrates a configuration for obtaining normal force
amplification caused by the sudden increase in guide surface
spacing and by wedging under the high forces of deceleration.
The moment equations for the initial and final states are

(8) TS1 =
Ni Ai

and

TSf = NfAf

Here, if the
geometry is made correctly, the initial band tension can equal
the final band tension, or, from Equations (8) and (9),

(10) NiAi
/ Si = NfAf / Sf

from which the ratio
of final to initial normal force can be found:

(11) Nf /
Ni = AiSf / AfSi

Evaluating Ai
and Af:

(12) A = {[ d1
+ d2 / 2 + t ]} cos alpha

(13) Nf /
Ni = Sf cos alphai / Si
cos alphaf

As 
=> Af , cos Af => 0 and Nf
/ Ni => infinity. Practically, Af cannot get too
small or the rollers would be able to unlock because of the
elastic deformation associated with Nf. This explains the
force amplification resulting from sudden reductions in the
axial roller spacing. The force attained through the rapid
deceleration by wedging can best be estimated from the total
energy supplied to the roller cluster by assuming a stopping
distance delta. Here

(14) Fw ~
W / delta

where

Fw =
wedging force   
 W = input
energy to cluster   
 Delta =
deceleration distance

Slipping between the
band guides and rollers would be precluded by the high contact
angle. Friction locking, if desired, may also be obtained.

**Figure 14:**
Detent Designs which hold or position the cluster until a
breakaway force can suddenly release it. There are many
methods of providing adjustment and just a few are shown. Rear
roller detenting is preferred because the band provides a
smooth radius to roll out of the groove and the tendency to
jam is less. Conversely, front roller detenting is better when
very high breakaway levels are needed.

![](1me14.jpg)

*Detenting
Mechanisms:* There are many methods of detenting, that
is, holding or positioning the roller cluster until some
desired breakaway force or energy level is experienced, and
then suddenly releasing the cluster. A few types of detents
are shown in Figure 14.

A guide surface slot
is one of the simplest types of detents and its breakaway
level may be adjusted by varying the distance the roller is
permitted to drop into the detent or by adjusting the band
tension.

**Figure 15:**
Roller-Flat Detenting utilizes the normal force for breakaway.
It is a function of tan 0 (providing 0 is small). Adjustable
stop can also be applied to this type to partially rock the
roller forward (i.e., reducing 0 ).

![](1me15.jpg)

**Figure 16:**
Negative Spring Detent force opposes weight. The screw is
turned until the desired breakaway level is reached.
Thereafter the energy surplus causes a fast breakaway.

![](1me16.jpg)

Another method of
detenting shown in Figure 15 is to flatten an area on the
surface of one roller so that the normal force induced by the
band tension at the point of tangency of the roller and guide
surface can be used to provide a breakaway force level. The
rear roller is the preferred location for frictional locking
to occur during breakaway. If desired, an adjustable stop can
be used to rock the roller forward and partly out f the detent
notch to diminish the breakaway level for calibration
purposes. One such arrangement is shown in Figure 16.

Accurate and
repeatable breakaway level detent action is obtained by using
detents which are provided by a negative spring-constant
region containing the desired force level. Negative spring
constants may be achieved by such means as cutouts in the band
or preformed curves. Of course, the steeper the negative slope
region, the sharper the breakaway action. Once the set force
level is exceeded, there is clearly an excess of force.

**Figure 17:**
Disc Braking wedges a bar against the wall (or the other
roller in the inter-roller version). The forces involved in
the sudden deceleration are at a minimum. If braking were to
occur on the lower wall (cluster moves to left), the roller
would attempt to roll up on the bar and severe damage could
result.

![](1me17.jpg)

*Braking &
Clutching:* Stopping the roller cluster directly by
over-roller or inter-roller braking (Figure 17) is primarily
useful I a high-shock situation in which the cluster must not
impact against the end of the device. For example, in
over-roller braking, the bar wedges between the upper side of
the roller and the wall, providing quick friction braking.
Gradual friction braking would be useful in extremely high
axial shock or acceleration situations. Gradual braking can
minimize the loading on the side walls, rollers, and end caps
after an extremely high kinetic energy level has been attained
by the cluster (See Figure 18).

**Figure 18:** Gradual
Braking is similar but uses a compressible pad instead of a
rigid bar. It minimizes the loading on the walls and rollers
when extreme speeds are reached by the cluster.

![](1me18.jpg)

**Figure 19:**
Band Tension Clutch is the simplest form. When the pin is
removed, the tension is released and the rollers are free to
rotate in place.

![](1me19.jpg)

**Figure 20:**
End-of-Stroke Decoupling is shown here with one roller part of
a flywheel. The shaft socket is not a necessity but it does
reduce friction. A positive stop is provided for the upper
roller to prevent wedging.

![](0me20.jpg)

The simplest form of
friction clutch is one based on controllable release and
reapplication of band tension, as shown in Figure 19. Another
version of this clutch can be used to decouple the rollers at
the end of a stroke. This is also depicted in Figure 20 in a
situation where one of the rollers functions as a flywheel.
Decoupling at the end of a stroke may be necessary so that the
rotary kinetic energy will not have to be rapidly absorbed, or
it may be desirable to use this rotary kinetic energy to
accomplish some other task.

**Figure 21:**
Dual-Action Overriding Clutch ~ Forcing the top roller to the
left, or lower to the right, causes jamming and the cluster
becomes friction-locked, but in a rollable attitude. The
asterisked forces are used for release.

![](1me21.jpg)

The use of a high
contact angle (gamma) for the cluster and a relatively stiff
band only lightly tensioned permits attainment of overriding
clutching action for the cluster. This capability is depicted
in Figure 21. Driving or forcing the top roller to the left or
the bottom roller to the right causes the rollers to jam with
a tendency to further increase gamma. Jamming causes the
normal force N to increase, as predicted by Equation (15), and
the geometry becomes friction-locked in a rollable attitude
(FT or B is the driving force applied to the top or bottom
roller).

(15) N = TT or
B tan gamma

and, since tan
gamma, for gamma's very close to 90 degrees, is very large, N
will be large; consequently, the frictional forces will be
large even if FT or B is relatively small.

On the other hand,
driving or forcing the top roller to the right or the bottom
roller to the left by the forces designated by an asterisk in
the figure causes the rollers to tend to decouple and decrease
gamma. The only torque required to turn the rollers is that
required to overcome the frictional torque between the loose
band and rollers. The coupling or decoupling forces can be
applied in any way to the rollers, not necessarily by means of
drums or tongues as shown. The coupling forces must at least
permit rotation, but the decoupling forces can be applied so
as to preclude gross rotation. However, considerable force
would have to be provided initially to break the friction
coupling to achieve decoupling if at least a small amount of
rotation were not permitted.

*Sequencing,
Recording & Limiting:* The rolamite geometry can be
used to insure that a certain combination of input function
types, signatures, directions, or amplitudes be experienced by
the device in the proper sequential order for output to be
permitted at some later time.

**Figure 22 / 23:**
Sequencing by means of a short tongue feed through, in (1) the
tongue is on the rear roller; (2) passing through; (3) the
tongue has popped up; (4) end of the stroke. Reversing the
cluster can go back to (3) but no farther since the erect
tongue will not pass between rollers. The photo shows several
short tongues and also a long tongue used to move the cluster.

![](1me22.jpg)![](1me23.jpg)

There are some
distinct ways in which the geometry can provide the sequencing
behavior. One method utilizes the short-tongue feed-through
arrangement shown in Figure 22. In the initial position,
position 1, the short tongue is on the left or rear roller; in
position 2, the tongue is just passing through between the
roller; in position 3, the tongue has popped up again; in
position 4, the end of the cluster stroke, the tongue can be
used for contacting or some other function.

Upon reversal, the
cluster may return to position 3, but is not permitted to go
any farther because the erect tongue will not pass through the
rollers. Combination of this action with a specially shaped
force-deflection bias provided by the band, and possibly
additional detenting action, could provide a very
sophisticated sequencing routine, like that of Figure 23.

**Figures 24 / 25:**
Simple Speed Changers ~ The photo demonstrates how the speed
ratio can be changed using the same guideways. Sketch (b)
shows an inertially restrained speed changer.

![](1me2425.jpg)

**Figure 26 / 27:**
The photo is a model of a variable surface velocity selector
in which there are seven linear speeds available in addition
to cluster speed. The drawing shows an inertially driven
oscillator with variable surface speed and amplitudes.

![](1me2627.jpg)

**Figure 28:**
Multiple Roller Cluster arrangement which provides many
different relative rotational velocities all moving at the
same linear speed. Multiple clusters also can serve to
increase the total wetted perimeter of the band so that more
travel with a force bias can be achieved, or to increase the
number of sequencing functions one short tongue can perform.

![](0me28.jpg)

*Speed Changing:*
Figures 24-28 show a few of the speed-change possibilities.
Single-stage speed changes have been successfully demonstrated
in which step-up and step-down rations as high as 300 to 1
were used.

Both linear speed
ratios and angular velocity ratios are available according to
rolamite arrangement or usage.

*Types of Motion:*
Cycloidal types of motion which are available provide
excellent sources of contacting, cutting, counterbalancing,
and instrument indicator actions and can approximate almost
every type of planar curve. Certain portions of the
trajectories exhibit extremely high mechanical advantages as
well. The roller counter-rotation can provide ideal action for
fusing, aligning, valving, etc., or can be employed to permit
either response to or rejection of angular acceleration inputs
(See Figure 29).

**Figure 29:**
Types of Motion such as cycloidal and trochoidal are available
by attaching parts to the rollers. Path 1 is on the surface of
the roller. Paths 2, 3, and 4 show the effect of an increasing
radius and illustrate the motions of points on a flywheel, for
instance.

![](1me29.jpg)

Counter-rotation can
also be used to provide counter-balancing with respect to all
inertial inputs. Because cluster motion in either direction
provides both clockwise and counterclockwise motions, the
designer has additional flexibility in solving his problems.
The inertia-to-mass ratio can be regulated by roller design to
produce cluster behavior approaching that of a point-mass on
the one extreme, or can be maximized by employing rollers with
flywheel proportions to provide long-range inertial odometer
behavior.

*Pumping Fluids:*
The conventional cluster becomes a very effective frictionless
piston if a rectangular tube with a small side clearance is
used to house and provide guidance surfaces for the cluster.
The band tension provides normal forces which neatly seal the
rollers at the three contact zones of Figure 10, A, B, and C.
Side-guidance surfaces in the channel prevent tip leakage in
two of the three short leakage path areas and permit the
device to work in any orientation without appreciable wear or
friction.

By using a
collapsible tube in conjunction with the band, as shown in
Figure 30, a much smaller displacement of fluid per inch of
cluster stroke may be obtained.

**Figure 30:**
Pumping Arrangement using a collapsible tube squeezed between
the rollers. Note that in the photo the band is not continuous
as though it were with respect to the tube. The pumping stroke
is applied to the loose end moving it to the right. The spring
provides the return force. In an actual pump, of course, check
valves would be needed. Any desired fluid displacement per
inch of stroke is easily obtained by roller sizes and tube
diameters.

![](1me30.jpg)

*Sensing
Temperature Change:* If the band is suitably made of
bimetallic materials, the cluster can be made to respond
sensitively to temperature changes induced environmentally,
internally by dissipation of electrical energy, etc. The low
rolling friction of the cluster permits high band tensions to
be used without introducing appreciable friction, so that the
output force or energy from a bimetalically driven device can
be sizable. Tow useful methods of accomplishing thermally
induced bimetallic driving of clusters are shown in Figures
31-33

**Figure 31:**
Single-Band Thermostat employs a bimetallic portion of the
band to counteract the triangular cutout.

![](1me31.jpg)

**Figure 32:**
Two-Banded Thermostat uses a bimetallic strip fastened to one
roller opposing a spring-loaded band.

![](1me32.jpg)

**Figure 33:**
Snap-Action Thermostat has a full band, but this cut-out
yields a negative spring constant. The bimetallic element
looks like Figure 32 but actually is preformed and thus tends
to move the cluster to the left. At a high enough temperature
this tendency is insufficient and the cluster snaps to the
right.

![](1me33.jpg)

*Electrical
Contacts:* Many of the means for locally amplifying
forces while also permitting some relative sliding are
suitable for electrical contacts. The combination of high
force and sliding action insures that the contact surfaces
penetrate through and scrub off oxide films, contaminants, and
particles which would prevent clean repeatable contacting:
Figure 34.

**Figure 34:**
Cross-Curved Band ~ In going from A-A to B-B the tape flattens
out, undergoing a sliding action with high unit forces at the
edges. Since the curvature with respect to the guide surface
at E-E is in the opposite direction, the same action does not
take place.

![](1me34.jpg)

**Figure 35 / 36:**
Side-Buckling Contact Electrical Switch utilizes the action
described in Figure 34. This continuous wiping motion cleans
oxides and contaminants, thereby providing dependable
electrical contact. Figure 36: Cut-Out Roller Contact (right)
~ During the scrubbing phase, differential sliding occurs
because the point of contact is no longer the rolling radius
of the roller.

![](1me35.jpg)  
 ![](1me36.jpg)

**Figure 37:**
Contact Orientations ~ Repulsive opens by itself if the
driving force is removed. Neutral stays closed but opens
easily. Locking requires considerable force to open.

![](1me37.jpg)

In addition, the
high-contact pressures help insure low ohmic contacting.
Figure 35 shows one arrangement for achieving this action.
With the cutout roller contact of Figure 36, the roller
centerline need not lift up to achieve contact engagement.
Once the unbacked portion of the band begins to touch the
contact block and is deflected inward, differential sliding
occurs since the contact point is no longer at the rolling
radius of the roller. This insures that contact scrubbing
action will take place.

Three orientations
of the contact block relative to the final rest position are
of interest. One gives a repulsive contact (one which tries to
open itself if the driving force is removed), one gives a
neutral contact (one which will stay closed but which will
open very easily), and one give a latching contact (one which
requires considerable force to open): Figure 37.

**Part 4: Hardware**

*Bands:* Bands
for use in rolamite geometries may be made of any material
which is strong under tensile loading and flexible enough to
undergo the required number of cluster movement cycles (Figure
38). Usually this also means that the flexing cycle should not
permit plastic behavior unless such behavior is to damp out
oscillations. In any situation, however, the active regions of
the bands will necessarily be thin relative to the roller
diameters with the ratio of t/d < 0.020 in most cases.

If the flexural and
tensile properties only are important, the best performance
will be given by band materials which yield the highest ratios
of yield stress divided by the tensile modulus of elasticity.
For a given thickness of band, such materials would insure the
lowest maximum stress; or if maximum tensile strength is
needed, they would permit using the strongest band without
obtaining plastic behavior.

Maximizing this
ratio does not necessarily minimize the frictional losses
displayed by the rolamite cluster. Flexural hysteresis losses
can be minimized by using a material which exhibits minimal
internal damping while displaying a high ratio of yield stress
divided by the tensile modulus of elasticity. And then
selecting roller diameters, shapes, widths, etc., which permit
minimizing the ratio of t/w where w is the band width.

Rolling friction
losses can be minimized by employing high modulus materials
for the rollers, guides and bands, by using the best available
surface finishes, by reducing the coefficient of sliding
friction between the rollers and guide surfaces and the band,
by using dry lubricants, surface coatings, oxides, etc., and
by using the lowest band tension consistent with performance
requirements. To date, all of Sandia's rolamite devices use
metal bands or plastic-metal composite bands where insulated
electrical conductors must be provided within the active
portion of the band but several devices with plastic bands of
Mylar, Kapton, and Teflon-impregnated woven fiberglass have
operated satisfactorily.

Not only must the
band material be carefully selected but also the exact
condition of the material must be controlled if a consistent
repetition of behavior of subsequent units is to be achieved.
Sandia has found that several of the age-hardening spring
metals in their fully cold-worked and age-hardened state best
fill the present rolamite component needs by offering high
yield strengths while retaining enough elongation to eliminate
a critical crack propagation situation. Spring metals used
include such alloys as beryllium copper 25 and 17-7 PH
stainless steel.

The bands may be
shaped by standard processes such as machining or chemical
etching, or controlled electroforming.

In general, those
methods which do not raise burrs or cause thickness variations
are preferable even if the width definition is not highly
refined. In the axial force equation the thickness terms
appears raised to the third power while only the first power
of width applies. Therefore, whether axial forces are to be
generated intentionally or not, variation in the band EI
(where I is the cross-section area moment of inertia for the
band) introduced by the band material fabrication process will
result in axial force variations.

In addition to the
variations which are useful in or near the working portion
(that portion which is actually permitted to flex as the
cluster moves between its two limiting positions), several
other types of features become useful only in regions of the
band well removed from the working portion. These features may
provide structural attachment, positioning, electrical
circuitry, electrical circuit termination, electrical
contacts, electrical connector pins or sockets, electrical
cabling, electrical connectors, mechanical fastening,
auxiliary side bands, commutating contacts, potentiometer
resistive elements, and lateral compliance. Having these
features provided by the band can insure fabrication and
assembly advantages over separate piece-parts.

The structural
portion of the band can be made of material of any required
thickness and joined to the thin active layer or layers by
means such as spot welding or silver soldering, which would
leave metal interfaces conductive, or through use of
insulating adhesives and additional plastic films if desired.
By having these additional layers provided only where they are
needed, many additional processing steps are eliminated and a
minimum amount of material wastage occurs.

By adding these
layers as continuous strips to a full-width backing layer,
special flexible strip laminates are obtained, permitting the
band patterns to be arrayed transversely very closely spaced.
Thus, a very efficient manufacturing process becomes possible
for the automated production of highly sophisticated rolamite
bands which are capable of replacing a great umber of
individual parts.

*Rollers:*
Although not quite as subject to variations as the bands, the
rolamite rollers may have several different configurations
other than the simple straight right circular cylinders shown
thus far. Such changes would allow the ratio of inertia to
linear inertia to be varied, for example.

**Figure 38:**

![](1me38.jpg)

**Figure 39:**

![](1me39.jpg)

Multiple threads
could be used to provide two regions of clearance between
rollers and guide surfaces. Circumferentially grooved rollers
could be used for attaching, adjusting, stopping, or coupling
adjacent clusters. Single and double hubs could be used for
weight and inertia control. Single and double cups could also
be used for weight control and to provide room inside rollers
for some useful purpose. Flanged rollers could provide
guidance and permit sustained operation in the presence of
side loads.

*Parallel Support
Geometry:* Parallel plates and channel forms allow access
to the rollers, rectangular tubes provide good
strength-to-weight ratios and band attachment and alignment
characteristics. Cutaway tubes combine several of the
foregoing attributes. Compliant guide surfaces allow automatic
tightening of the band and provide cluster compliance (Figure
40).

**Figure 40:**

![](1me40.jpg)

Several useful
features may be incorporated in the support geometry. Notches
may be used for detenting, decoupling, clutching, etc.
barriers or bumps are useful for stops or energy level
detents. Changes in level are used in detenting and in
changing the cluster repose angle. Divergence in the support
can provide gradual changes in cluster tension, axial force,
etc. Undulations allow soft detenting and slow decoupling.
Wedges provide braking actions and force amplification or
attenuation.

**Summation**

The rolamite
geometry is adaptable to modularity, microminiaturization, and
a very broad calibration of forces. Additionally, it can
utilize the highly desirable advantages of multiple-use
laminates, which may be the first step toward the ultimate in
manufacturing efficiency --- one-piece mechanisms for
continuous-strip processing techniques.

Good performance has
been attained in the many devices and prototype mechanisms
assembled to date. Yet the rolamite technology is in its
infancy and much remains to be learned if the full potential
of rolamite is to be exploited. Most of the instrumentation
and testing methods required to record completely and
accurately rolamite behavior, particularly in microminiature
sizes, are either nonexistent or in the early stages of
development. It is clear, however, that the use of the
rolamite geometry is an effective way to design
electromechanical weapon components and that the rolamite
geometry can be used to advantage in many applications,
including electromechanical weapons components, biomedical
components, household devices, toys, and so on.

---



**US3452175**   
 **Roller-Band Devices**   
 **Donald
F. Wilkes  
[ [PDF](US3452175A.pdf)
]**

**Abstract --** A
roller-band device which substantially eliminates or minimizes
sliding friction; the device having a plurality of rotatable
members in a guideway with generally equidistantly spaced
walls, with each wall supporting and restraining one of the
rotatable members and separated from each other less than the
summation of the diameters of the rotatable members, and a
flexible band between the guideway walls having a portion
disposed between the rotatable members at leas partially
encompassing at least one member, the band holding the members
with generally parallel axes and providing rolling motion
between each element of the device.

**Background of the
Invention**

In prior
electro-mechanical and mechanical devices which transferred
one form of motion or energy into another such as bearings,
gear systems, condition sensitive switches, etc., the
accuracy, efficiency, and sensitivity as well as the life of
the devices have been limited by the degree or amount of
sliding friction inherent in the device or sliding friction
resulting from structural inaccuracies in the elements used in
the device. In attempting to compensate or minimize sliding
friction losses, compromises in construction are sometimes
made which contribute further limiting factors in efficiency
and sensitivity of the device under some operating conditions.

Attempts to minimize
friction often resort to lubrication of the moving parts with
various liquid, gaseous or solid lubricants. These lubricants
may create forces which are detrimental to the operation of
certain devices under highly sensitive operating conditions.
The lubricant may contaminate critical areas within the
housing or a portion thereof and require packing or sealing
materials to prevent contamination and thus create other
friction losses. Further, under extreme operating conditions
such as high and low temperatures and prolonged storage,
lubricants may not perform in the desired manner and may
effect either partial or complete device failure.

The efficiency of
land bearing surfaces has always been limited by the ability
to fabricate precision surfaces or dimensions. For instance,
in bearings such as roller-bearings, misalignment of rollers
results in end frictional losses and attempts to provide
closer alignment with caging frequently results in additional
frictional loses therebetween. If the losses in adjacent
roller ends can be minimized, surface roughness on the rollers
may cause additional losses which may substantially exceed any
attainable rolling coefficient of friction, thus placing a
lower limit on overall efficiency.

In devices such as
accelerometers or G-switches, attempts to increase the
accelerometer's sensitivity by decreasing sliding friction
between the various elements of the device may also decrease
the force applied between the electrical contacts closed by
the devices reactions an acceleration force since this force
is generally dependent upon opposing sliding members. Further,
such devices generally may not be adjusted to respond
accurately to a relatively wide range of acceleration force
due to unpredictable and variable frictional losses between
the device's members.

Prior electrical
potentiometers are also dependent and limited y sliding
frictional forces between the contacts or contacts and
resistance material. Any attempt to decrease the sliding
frictional force to increase component life or sensitivity may
result in a decrease in resistance linearity.

The problem became
particularly acute in modern microminiaturized technology
since the adverse effects of any friction may be greatly
amplified relative to the size and forces available to
activate the device. It has been shown that the friction force
approaches a constant level for normal loading under about 10
grams, which makes it hard to achieve a reasonable driving
force to friction ratios in microminiature devices. Further,
it is difficult to fabricate these devices so that they can
perform multiple functions or provide a complex response to a
predetermined or desired situation, environment or event. For
instance, it may be desirable that a G-switch have one or more
open or closed electrical contacts in its quiescent state, be
accurately adjustable over a given range of acceleration
force, be capable of sensing whether the acceleration force
continued for at least a given period (and if not have
automatic reset capabilities), be stable over long periods of
time and over wide ranges of operating conditions, have one or
ore open or closed electrical contacts in its activated state,
provide latching in its activated state, and be relatively
sensitive to load components not on the sensitive axis.

It is desirable in
this area of technology that a mechanism or apparatus be
capable of modular construction, e.g., that the mechanism be
constructed of standardized parts that can be assembled to
perform a wide range of functions depending of the particular
parts used and the environment in which the device is used.
Using a given module, a wide range of devices can be
fabricated using mass production techniques to perform a wide
range of functions without providing separate tooling and
production facilities for each device. Such modular
construction can provide commensurate per unit tie and cost
savings while permitting the facility to be converted in a
minimum of time to the production of another modular device
performing an entirely different function.

Sliding friction may
be decreased by further precision fabrication, closer
tolerances and the use of such sophisticated techniques such
as air bearings. However, there is generally both a financial
and a technology limit to these approaches and the devices
become increasingly sensitive to environmental conditions such
as temperature, moisture and surface contaminations such as
with dirt or dust.

Since rolling
coefficients of friction are considerably lower than sliding
coefficients of friction, it is desirable to provide
electro-mechanical or mechanical devices having only rolling
friction losses. Rolling coefficients of friction have been
measured as low as about 0.00001 to 0.00002 for right circular
cylinders whereas roller bearings and ball bearings have
attained coefficients of friction of only about 0.001 to 0.005
due to the loss mechanism noted above and several others which
have not been mentioned.

**Summary of
Invention**

In view of the
limitations of the prior art such as noted above, it is an
object of this invention to provide mechanisms having
substantially only pure rolling friction losses.

It is a further
object of this invention to provide mechanisms exhibiting low
coefficients of friction without use of lubricants.

It is a further
object of this invention to provide mechanisms having
substantially no adverse effects from surface deformities on
load bearing surfaces.

It is a further
object of this invention to provide electrical switch
mechanisms having only rolling friction losses while having
high contact pressures.

It is a further
object of this invention to provide mechanisms which may have
force biases applied thereto.

It is a further
object of this invention to provide mechanisms having
adjustable negative force bias with only pure rolling friction
losses.

It is a further
object of this invention to provide a substantially
frictionless piston mechanism which may be displaced by or may
displace fluids.

It is a further
object of this invention to provide mechanical bearings having
only rolling friction losses.

It is a further
object of this invention to provide mechanisms having only
rolling friction losses which are capable of modular
construction.

The invention
comprises a roller-band device having a guideway with
oppositely spaced walls, at least a pair of rollers
intermediate the guideway walls with combined cross-sectional
dimension greater than the spacing between the walls, and a
flexible band supported within the guideway and reversibly
looped about the rollers so as to effect rolling movement of
the rollers and band longitudinally along the guideway.

**Description of
Drawings**

Embodiments of the
present invention are shown in the accompanying drawings
wherein:

**Figure 1** is a
side elevation view, partially in cross-section, of a
roller-band device with generally parallel guideway walls and
right circular cylinder rotatable members;

![](0usp1.jpg)

**Figure 2** is a
side elevational view, partially in cross-section, of a
roller-band device of the type shown in Figure 1 but with
uninterrupted guideway walls;

![](0usp2.jpg)

**Figure 3a**
through **3*l*** are diagrammatic views of tension
band configurations and the resulting force biases;

![](0usp3ae.jpg)![](0usp3fj.jpg)![](0usp3kl.jpg)

**Figure 4a** is
a view of a tension band having electrical conductors embedded
therein;

![](0usp4ab.jpg)

**Figure 4b** is
a cross-sectional view taken along line B-B of Figure 4a;

**Figure 5a**
through **5c** is a side elevation view, partially in
cross-section, of a portion of a roller-band device showing
various rotatable member geometries;

![](0usp5ad.jpg)

**Figure 5d**
is  across-sectional end view of a roller-band device
having spool-shaped rotatable members;

**Figure 6** is a
cross-sectional side view of a roller-band G-switch;

![](0usp6.jpg)

**Figure 7**
is  across-sectional view taken along line 7-7 of Figure
6;

![](0usp7.jpg)

**Figure 8** is a
view of the tension band shown I Figure 6 and the force
diagram of the tension band;

![](0usp8.jpg)

**Figure 9** is a
cross-sectional side view of a roller-band device which may be
used to sense or measure acceleration or velocity;

![](0usp9.jpg)

**Figure 10** is
a side-view, partially in cross-section, of a 2-level
accelerometer G-switch;

![](0usp10.jpg)

**Figure 11** is
a cross-sectional side view of the present device as it may be
used to pump fluids;

![](0usp11.jpg)

**Figure 12** is
a cross-sectional view of the device utilized as a speed
converter;

![](0usp12.jpg)

**Figure 13** is
a cross-sectional side view of a roller-band electrical
potentiometer embodying the present device;

![](0usp13.jpg)

**Figure 14** is
a cross--sectional side view of the roller-band device
utilized as a force amplifier;

![](0usp14.jpg)

**Figure 15** is
a cross-sectional side view of a heavy load-bearing
roller-band device; and

![](0usp15.jpg)

**Figure 16** is
a side elevation view, partially in cross-section, of a
roller-band device having a curved or arcuate guideway and
right circular cylinder rotatable members.

![](0usp16.jpg)

**Detailed
Description**

By way of
introduction, the mechanism shown in Figure 1, which may be
referred to as a "roller-band" device, illustrates various
features and principles of this invention. As shown,
roller-band device 10 includes a group or pair of adjacent
rotatable members or rollers 12 and 14 supported between
equidistantly spaced restraining surfaces or walls 16 and 18
of a guideway by a flexible, tensioned band or ribbon 20. Band
20 extends in generally S-shaped configuration partially
around members 12 and 14 and may be held under tension by
suitable fasteners 22 and 24, such as screws or bolts, which
attache band ends at opposite extremities of the guideway on
opposing walls. The guideway walls 16 and 18 are supported at
either end by end blocks or walls 26 and 28. The summation of
the diameters of the rotatable members is at least slightly
greater than the distance between walls 16 and 18 of the
guideway.

In the embodiment
illustrated in Figure 1, rotatable members 12 and 14 may be
right circular cylinders of any convenient length. Tension
band 20 in this embodiment may be a flat elongated band of any
convenient constant width and any convenient thickness. For
purposes of illustration, tension band 20 is shown with
exaggerated thickness since generally it may be from about
0.0002 to 0.004 inch thick for instrumentation usage. The
guideway, which includes walls 16 and 18, may also include
side walls (not shown) depending on the application of the
invention.

As shown rotatable
members 12 and 14 are in an initial position with member 14
and the corresponding contiguous portion of tension band 20 in
latch or detent 30 in wall 18. If a predetermined force
function is applied in the direction of the arrow (for example
by acceleration of the device toward the left) which is
sufficient to overcome the forces of tension band 20, inertia
of members 12 and 14 and band 20, the coefficient of friction
(e.g., rolling friction), and the band tension holding roller
14 in detent 30, member 14 may be released from the detent. If
this force function or some lesser force (now only dependent
on the band tension friction and inertial forces) continues,
members 12 and 14 may continue to roll along the guideway
until the force function is discontinued or members 12 and 14
may continue to roll along the guideway until the force
function is discontinued or member 14 reaches energy barrier
32. If sufficient force is applied over the travel of the
rollers to raise the kinetic energy above some threshold
provided by the combination of height and width of the barrier
and the increased tension placed n tension band 20, the
members may roll over barrier 32 and drop into latch or detent
34 as shown by the dashed representation of the rotatable
members and tension band. In order to unlock the roller-band
device in a reverse direction, a force would have to be
applied in the opposite direction to overcome both detent 34
and barrier 32.

Roller-band device
10 may operate a switch contact or microswitch 35 or be
provided with electrical contacts on the ends of either member
12 or 14 and on the appropriate wall of the guideway, or
tension band 20 can be used as an electrical contact and
another contact provided within detent 34 in wall 18 so that
an electrical circuit is completed when member 14 reaches
detent 34. thus, the roller-band device shown in Figure 1 may
be used to measure or sense a force or combination of forces
and the integration of the forces over a given time determined
by the length of the guideway. Such devices can be released
from detent 30 and rolled over barrier 32 with an accuracy of
plus or minus a fraction of a percent of predetermined force
levels.

With the general
construction and operation of the Figure 1 type of device in
mind, reference will now be made to the simplified roller-band
device of Figure 2 in order to explain more of the principles
of the device. As in Figure 1, roller-band device 42 includes
a group or pair of adjacent rotatable members 44 and 46
supported between equidistantly spaced walls 48 and 50 of a
guideway by a flexible tension band 52. Rotatable members 44
and 46 are shown in an initial position adjacent end wall 47,
with the band 52 shown departing from contact with walls 48
and 50 at contact "lines" or lines of tangency 54 and 56.

As the band 52 is
looped or threaded around members 44 and 46 and fastened under
tension by suitable means to diagonally opposite ends of walls
48 and 50 of the guideway, the band tension produces a torque
which urges the rotatable members firmly toward their
respective restraining walls 48 and 50 and holds their axes
parallel to each other, the combined effect of band tension
and restraining walls being to urge the rollers firmly toward
each other. With the rollers in the noted initial
relationship, the position of the contact lines or zones may
be varied to an extent by changing the tension of the band.

By way of
explanation, it appears that the force (F) to effect movement
of the rotatable members contributed by any one of the three
rolling contact zones (at contact lines 54 and 56 and between
rollers 44 and 46) is equal to the coefficient of rolling
friction (mu, *u*) times the applied normal force (N) at
that zone induced by the tension band and inertial forces. At
any one zone:

(1) F = *u*N

so for the entire
geometry, the total frictional force (Ft):

Ft = *u*1N1
+ *u*2N2 + *u*3N3

The normal force (N)
results from the tension applied to the band and the inertial
forces of the system. Since the inertial forces of the
rotatable members and band and the coefficient of friction are
relatively small, the tension applied to the band may be the
primary variable used to control or predict (F).

Since the tension
band 52 is shown bent around a portion of each member 44 and
46 in opposite directions, energy stored elastically in the
S-shaped part of the band applies opposite resultant forces
which emanate from the axes of each rotatable member, likewise
the axial components of these forces Fb in opposition in the
direction of each band parallel to the guideway walls at each
contact line or zone is defined by the following formula where
force is measured at the center of one or the other where:

(3) Fb =
WE*h*3 / 12R2

where

W = width of band at
line contact,   
 E = modulus
of elasticity of band at line contact,   
 R = radius
of rotatable member, and   
 *h* =
thickness of band at line contact.

If the band
parameters W, E and *h* are equal at both zone or lie
contacts 54 and 56 and the radius of the members are equal,
the opposing forces (Fb) will be equal and the roller-band
device will be in a state of equilibrium or rest in the
absence of any external forces. The direction and magnitude of
these forces are essentially independent of the band tension.
Because one or more of the parameters of the band may be
different at line contacts 54 and 56 (defined as positions 1
and 2 respectively):

(4) Fb1 /
Fb2

resulting in an
unbalanced force (Fr) being applied to the
rotatable members. If for instance force Fb2 is
larger than the force Fb1, the force bias (Fr)
will be applied to the rotatable members in the direction of
the arrow. If the width (W) of the band is varied, the formula
for the unbalanced forces becomes:

(5) F1 =
(W1 - W2) Eh3 / 12R2

The other variables,
E, h and R, may be varied to apply a force bias to the
rotatable members.

Axial forces may be
introduced by employing a band with preset loops or curves.
These loops or curves may be formed by conventional tempering
or cold forming processes. Forces may also be introduced by
varying the material longitudinally in the band by laminating
or connecting together various materials along the band by
conventional processes.

Figures 3a to 3*l*
illustrate various tension band configurations which provide
various band width combinations at the line contacts with the
guideway walls showing the resulting force bias (Fr) applied
to the tension band and consequently the rotatable members.
The tension band configurations in Figures 3a to 3l will be
applied to the roller-band device 42 shown in Figure 2. IT
will be assumed, for purposes of illustration, that the
vertical axis of the force diagram in each of the drawings
crosses tension band 52 at contact line 56 adjacent member 46
and that a portion of band 52 which partially encompasses
member 44 is contiguous with the end wall of roller-band
device 42.

In Figure 3a,
tension band 52a has a uniform width throughout this length.
Since the width of the band at line contacts 54 and 56 are
equal, the resulting force (Fr) is zero as shown in the force
diagram. This is the same configuration described with
reference to Figure 1.

In Figure 3b,
tension band 52b has a rectangular cutout 60b which begins to
the left of line contact 56 in Figure 2 and continues around
rotatable members 46 and 44, stopping just short of line
contact 54. The distance of contact this represents is also
the maximum travel the geometry can undergo without passing
out of the force zone. Using Equation 5 above, cutout 60b
generates a constant resulting force (Fr) in the opposite
direction of the arrow in Figure 2 (a positive force) for the
time in which the cutout 60b is adjacent the line contact 56.
Using tension band 52b with the roller-band device 42 of
Figure 2, the roller-band device may be used to measure
forces, such as acceleration forces, in the direction of the
arrow and the period of the force. If a negative force which
is greater than the force of the band cutout is applied to the
roller band device, the members and band may rotate may rotate
along the guideway for the duration of the force. If the force
continues for a time sufficient to allow the members to move
to a second position having line contacts 62 and 64 as shown
by the dashed lines in Figure 2 which are beyond the cutout,
the resulting force bias on the tension band will be zero and
the tension band will be in a state of equilibrium. If the
force does not continue for a sufficient time to allow the
members and tension band to reach line contacts 62 and 64, the
force bias will cause the members and tension band to return
to its initial position against the end wall.

Roller-band device
42 with tension band 52b may also be used as a condition
sensing switch by positioning the rotatable members and band
to the right of line contact 56 with cutout 60b still adjacent
to the line cutout and physically holding the member in that
position by a condition sensing means such as a fusible
material or a releasable magnetic latch (not shown). Should
the desired condition occur, the conditioning means may
release the members and allow them to return under the tension
band force bias to the end wall of the device and thus
energize a switch (not shown). Such a device may be used, for
example, as a circuit breaker or a circuit fault sensor.

In Figure 3c,
tension band 52c is tapered at a uniform rate throughout the
entire length of the tension band. Since the difference in
width of the tension band at the line contacts for each
rotatable member will be the same along the entire length of
the guideway, the resulting force (Fr) is constant. The
tapered band force is not limited by the length of the contact
of the band with the rollers as in cutout 60b in Figure 3b.
Using mechanical latching such as that shown in Figure 1 and
the concepts described with reference to Figure 3b roller-band
device 42, having tension band 52c, may perform the same
functions as band 52b.

It will be apparent
that tension band 52c may have a uniform width and a uniformly
tapered cutout throughout its length to provide the same force
bias.

In Figure 3d,
tension band 52d includes a complex cutout 60d, a portion of
which may be adjacent line contact 56 in configuration shown
in Figure 2, and a second cutout 58d, which may be adjacent
line contact 62 and member 44 as shown by the dashed lines in
Figure 2. Cutout 60d provides a similar positive force bias as
cutout 60b in Figure 3b except that the force bias has three
force levels with step changes between each level. Cutout 58d
provides a negative force bias which may function as a latch
similar to mechanical detents or latches 30 and 34 in Figure
1. The step function force bias generated by cutout 60d may
perform the same function as mechanical detent 30 in Figure 1.

In Figure 3e,
tension band 52e includes a pair of triangular cutouts 58e and
60e. The base of triangular cutout 58e may be adjacent line
contact 54 at one end of the force bias while the base of
triangular cutout 60e may be adjacent line contact 64. the
combined force bias generates a curve similar to a positive
spring constant having a stable position where the force bias
crosses the force diagram axis, e.g., where the apexes of the
triangular cutouts are both simultaneously adjacent to a line
contact about midway between line contacts 54 and 62 and 56
and 64 respectively. A roller-band device using tension band
52e may be used, for example, as a shock absorber or vibration
damper.

In Figure 3f,
tension band 52f includes a triangular cutout 60f having its
apex adjacent to line contact 56. The resulting force bias,
like Figure 3e s similar to a positive spring constant
exhibited by a helical spring.

In Figure 3g, the
generally concave tapered band width configuration shown
produces a parabolic shaped force bias, thus providing both a
positive and negative spring constant type force curve.

In Figures 3h, 3i
and 3j, various cutouts and band width changes in tension
bands 52h, 52i and 52j generate force biases which are similar
to a negative spring constant force pattern. These cutouts and
width changes operate on roller-band device 42 in the same
manner as shown in Figures 3e, 3f and 3g and described above.
By positioning the line contact of either tension band 52h,
52i or 52j adjacent rotatable member 46 along the force bias
curve, a wide range of forces can be measured by roller-band
device 42 using a single tension band geometry.

Figure 3k
illustrates an arbitrary force bias which may be generated by
a tension band such as band 52k merely by selecting the force
bias desired and then design an appropriate cutout or cutouts.

In Figure 3*l*,
the two series of circular cutouts in tension band 52*l*
generate a generally sinusoidal force bias. Such a force bias
may be used to provide multiple stable or detent positions for
rotatable members 44 and 46.

By choosing one or
more of the cutout or band width configurations illustrated in
Figures 3a to 3*l* or variations and combinations
thereof, any desired force bias may be generated with
roller-band device 42. There are some applications where it
may be desirable to use a primary force biased or non-biased
tension band and rotatable member pair in conjunction with one
or more secondary tension bands with or without their own
rotatable members having separate force biasing to obtain a
desired composite force biasing. The additional secondary
tension bands may act as a pusher or damping on the primary
tension band. Another typical force bias will be illustrated
in Figure 8 which may be used in particular applications of
the principles of this invention. For most applications it is
preferable to provide the desired force biasing with cutouts
rather than vary the outside dimension of the tension band
since the cutouts can be formed more precisely with
conventional techniques such as photographic etching
processes.

The tension band may
be of a wide range of flexible materials or combination
thereof depending on the particular application of the
roller-band device such as plastics, metals, alloys,
laminates, insulators, viscoelastic materials, etc. Typical
materials include aluminum, stainless steel,
beryllium-copper-plastic laminates, polyethylene terepthalate
(sold under the trademark "Mylar") and polyimides (sold under
the trademark "Kapton"). In some applications it may be
desirable to use a temperature sensitive bimetallic tension
band which will generate or modify force biasing in response
to temperature variations.

Figures 4a and 4b
illustrate a tension band having multiple electrical
conductors embedded therein. Tension band 34 includes a main
body or portion 36 which may be made of a suitable solid or
laminated material. A pair of aligned conductors 38 and 40 and
conductor 41 may be embedded in or laminated between the
insulating material of portion 36. Any number of conductors,
having a desired length, may be embedded within a tension band
such as band 34 depending on the required electrical circuits
or connections determined by the particular application of the
device (See the description of tension band 172 in Figure 10).
If it is desired to make contact with either of conductors
38,40 or 41 through the tension band walls, the insulating
material of portion 36 may be removed or separate contacts
fastened to the tension band at the point of desired contact.

In order to provide
flexibility and shock resistance in the tension band itself so
as to maintain the desired tension, ring or maze type cutouts
or corrugations may be provided at the band ends or the band
may be made of an elastic material.

The rotatable
members or rollers may be any suitable hollow or solid
cylindrical shape such as a right circular cylinder or right
prism and variations thereof. In most application, hollow or
solid, right circular cylindrical, rotatable members may be
sued (see Figures 1, 10 and 13) since they provide a
continuous rotating movement. The rollers may also be made
with one or more spring biased members which may be urged
outwardly against the side walls of the guideway to eliminate
the need to precisely control roller lengths as is needed in
some cases. Also, in some application desired force patterns,
detenting, latching, etc., may be obtained by using alternate
or complex rotating member shapes. The rotatable members may
also be formed in a spool shape as shown in Figures 5d and 10.

Figures 5a through
5c illustrate several typical roller-band devices, rotatable
members 66, 68 and 70, in addition to the right circular
cylindrical type shown in Figures 1 and 2, all partially
encompassed by tension bands 67, 69 and 71 and supported on
guideway walls 72. Rotatable member 66 is generally a right
circular cylinder having a flat portion 74. Rotatable members
68 have generally equilateral triangular polyhedron shapes
while the members 70 have generally triangular polyhedron
shapes with one curved portion 75. As member 66 rotates with
its band onto a flat portion of the member, such as portion
74, the roller-band device assumes a generally stable position
representing slightly decreased band tension and may function
as a detent or latch until a sufficient force in either
direction can rotate the member off the flat portion. Various
combinations of detents and latches may be incorporated in the
device with this technique. As can be seen in Figure 5, flat
portion 74 may provide additional compliance in the device
depending on the band tension to remove the criticality in the
tension setting procedure or provide shock absorbing ability.

A block 78 may be
positioned on the inner wall surface of guideway wall 72 so
that a rotatable member and tension band can be rotated over
the same.  As the rotatable member, such as member 66,
rotates over block 78 the normal force (N) introduced by band
tension, may be essentially recovered. If the block is
actually two or more contact points the normal force may be
shared equally among the contact points because of the
compliance provided by the flat portion 74. The small amount
of slipping induced by the slight reduction in radius at the
flat portion serves to remove oxide films or contaminants and
assure clean contacting. In flat portion 74 is positioned
adjacent block 76, additional wiping may be provided between
the contacts as well as a greater detenting or latching force
or a repulsive force created depending on the relative
positions of portion 74, block 76 and the center of member 66.

Where extreme
sensitivity is required, complimentary spool-shaped rotatable
members 77 and 78 may be used as shown in Figure 5d. Members
77 and 78 are shaped so that the members do not have surfaces
contacting opposing surfaces of tension band 79. The
configuration shown tends to reduce or substantially eliminate
the detrimental effects of any surface roughness on members 77
and 78. Surface roughness effects may also be substantially
eliminated by either increasing the band tension to cause
plastic deformation of the members and smooth out surface
roughness or decreasing band tension so that the members ride
on the peaks of surface roughness. Spool-shaped member 78 may
also be used where it is desired to decrease the mass of the
roller-band device and the resulting inertial forces.

The rotatable
members may be made of a wide range of materials with or
without coatings depending on the application of the
roller-band device and any force bias contribution desired
from the member. Typical materials which may be used are
metals such as beryllium, aluminum, stainless steel, brass,
beryllium-copper alloy and tungsten carbide or insulating
materials such as alumina, structural plastics, and rubber.

The guideway or
housing supporting or restraining walls may be made of any
suitable material depending on the application of the
roller-band device such as conventional insulating materials
and metals or alloys. Where the tension band is used as an
electrical conductor, the guideway may be coated with a layer
of insulating material. The guideway tension band supporting
walls can be provided with various detenting, latching, sears
and electrical contacts as shown in Figures 1 and 5 to perform
a wide range of functions with respect to the tension band and
rotatable members. The guideway side walls may be provided
with grooves or orifices to provide fluid damping in an
enclosed roller-band device between opposite sides of the
tension band and rotatable members. Further, the guideway side
walls may be provided with sears, wedges, electrical contacts,
magnetic actuated pin latches, etc., depending on the
particular applications of the roller-band device.

While roller
supporting walls are shown in the drawings as generally
equidistantly spaced from each other, either as flat parallel
members or as flat arcuate members, they may be of diverging
or converging relationship with respect to each other, so long
as the distance between them is at their effective operative
portions not greater than the sum of the effective diameters
of the rollers. In some specific application requiring special
or complex force bias functions, the guideway supporting walls
may be defined as the surfaces generated by passing two
parallel lines of equal length along two planar
non-intersecting lines wherein said parallel lines are
perpendicular to said plane.

The end walls may
also included various latching and detenting mechanisms as
well as adjusting screws for positioning or releasing the
tension band and rotatable members in or from a force bias.
The end walls may be made of any suitable material depending
on the application of the roller-band device and function as
performed by the end wall.

Various
modifications, forms and combinations of rotatable members,
tension bands, and guideways and their associated mechanisms
will be described hereinafter in connection with the following
embodiments of the roller-band device.

Figures 6 and 7
illustrate the present invention in one form of a G-switch or
accelerometer. A pair of adjacent rotatable members 80 and 82
are shown held under tension in an initial position between
guideway supporting walls 84 and 86, sidewalls 88 and 90 and
end walls 92 and 94 by tension band 96. Tension band 96 may be
held under tension by suitable fastening means such as screw
98.

Tension band 96
includes a complex cutout 100 and a rectangular cutout 101.
Cutout 100 is positioned as shown along the contact line of
member 80 and tension band 96 with wall 84. Cutout 101 is
positioned so that when member 80 and the band rotate past
cutout 100, cutout 101 will be adjacent the contact line
between member 82 and tension band 96 and wall 86 in the
device's final position. Tension band 96 also includes a pair
of oppositely facing U-shaped cutouts 102 and 104 leaving a
pair of tongue-like extensions 106 and 108 intermediate the
sides of the tension band 96. Tongues 106 and 108 extend away
from members 80 and 82 due to the curvature of tension band 96
as shown in Figure 6.  Tongue 108, in the initial
position of the roller-band G-switch, rests against the end of
adjusting screw 110 which is threaded through end wall 92. The
position of members 80 and 82 in the guideway may be adjusted
by screw 110 so as to position the contact line of member 80
and tension band 96 along the desired portion of the
triangular portion or negative spring constant of cutout 100.

Tongue 106 is
positioned on tension band 96 so that the tongue contacts the
flat contact 112 when the roller-band device is in its final
position in the same manner as block 78 in Figure 5.
Electrical leads are connected as shown to screw 98, screw 110
and contact 112 to provide an initial closed circuit between
screw 98 and screw 110 and an initial open circuit between
screw 98 and contact 112. It will be apparent that walls 84
and 86 may be either made of or coated with an insulating
material (not shown). In the roller-band device's final
position, there will be a closed circuit between screw 98 and
contact 112.

In Figure 8, the
resulting force bias created by cutouts 100 and 101 and tongue
106 is shown by the solid line 114. The force bias generated
by cutout 100 includes dotted line 116 and the negative spring
constant portion of line 114 as well as the constant positive
return force portion of line 114. Cutout 101 generates the
negative force bias or latching force portion of line 114
designated by 118. Tongue 108 generates a pushing force
against the rotatable members, shown by dotted line 120 so as
to insure a clean breakaway from the initial position after
long term storage. This compliant stop forces the rollers to
roll forward a small amount from the initial position to reach
the breakaway force level. The negative spring constant
ensures a snap action release.

When the roller-band
switch is accelerated in the direction of the arrow a force or
"set-back" is experienced in the opposite direction. If the
force is sufficient to overcome the rolling friction force (Ft
from Equation 2) the rotatable members and tension band may
begin to roll from their initial position determined by screw
110 and compliant tongue 108. If the force continues and is
greater than the force bias generated by cutout 100, the
rotatable members and tension band may continue to roll down
the guideway. If the force is maintained for a time exceeding
the time necessary for the rotatable members and tension band
to traverse the guideway so that the contact line between
member 82 and wall 86 is over cutout 101, the roller-band
switch may be locked in position with tongue 106 in contact
with electrical contact 112. If the force is not maintained
for the necessary time, the force bias generated by cutout 100
may reset the roller-band device to its initial position.

A roller-band device
has inherent directional sensitivity along the longitudinal
axis of the guideway. The deice is relatively insensitive to
extraneous side loads or forces because of the counteracting
balanced forces between the tension band and rotatable members
in the direction of the normal forces (N) so that for side
components of force perpendicular to the roller axes but less
than the total resultant normal force on both surfaces
constant and only small changes in mu associated with the
nonlinearity of mu versus load are experienced. This normal
force creates friction between the members, tension band and
guideway which acts to prevent such force components parallel
to the roller axes from displacing the rollers laterally which
is also aided by the band's side stiffness. Lateral motion may
be substantially eliminated by positioning blocks or guides
122 (Figure 7) along the periphery of members 80 and 82 on
sidewalls 88 and 90. Since the guides 122 are along the
periphery of members 80 and 82 at the position of lowest
relative velocity between each member and the guides, the
sliding friction introduced may be kept minimal.

If rollers with
equal mass moments of inertia are used they will not respond
to rotational acceleration components about the roller axes.
It will be apparent that the switch may be modified to be
sensitive to rotational acceleration components about the
roller axes by using rotatable members having different
inertias.

Figure 9 illustrates
a roller-band switch or accelerometer which has been modified
to measure both a G-level and velocity change. The roller-band
device includes a first pair of adjacent rotatable members 124
and 126 held under tension in an initial position as shown
between guideway supporting walls 128 and 130 and end walls
132 and 134 by a first tension band 136. Member 126 may be
provided with an orifice 138 passing through the center
thereof and aligned with an opening 140 in band 136. The
roller-band device also includes a second pair of adjacent
rotatable members 142 and 144 held under tension as shown
adjacent to member 16 by a second tension band 146. Tension
bands 136 and 146 may be fastened under tension in an
overlapping manner as shown by suitable fastening means at the
extremities of each band.

Tension band 146 may
be provided with suitable force biasing such as that shown in
Figure 8 with cuto0ut 100 and tongue cutout 102, leaving
tongue 106, in the same manner as tension band 96 in Figure 8.
Members 142 and 144 operate in the same manner as members 80
and 82 in the switch shown in Figures 6 and 7, responding to
forces in the direction of the arrow. The force level at which
the members respond may be selected by means of adjustment
screw 148. The force biasing in tension band 146 holds both
sets of rotatable members in the initial position. Tension
band 136 may have uniform width dimension throughout its
length similar to tension band 52a in Figure 4a.

The interior 149 of
the guideway may be filled with a suitable damping fluid,
liquid or gas. Members 124 and 126 and tension band 136 are
preferably closely dimensioned to that of the side walls so as
to limit gas leakage around the end s thereof and the side
walls shaped to provide guide rail type surfaces to prevent
excessive side friction while members 142 and 144 and tension
band 146 are loosely dimensioned to allow substantially
undamped movement.

When the roller-band
device is subjected to a predetermined or preselected
acceleration to the left, members 142 and 144 and tension band
146 may roll to the end of the guideway adjacent to end wall
134 with tongue 106 engaged or locked in ledge or shelf 150 in
wall 134. Simultaneously, members 124 and 126 and tension band
136 may begin to roll in the same direction since there is no
force biasing holding the rotatable members and tension band
in their initial position. The rate at which members 124 and
126 roll along the guideway is dependent on the rate of flow
of the damping fluid or gas through orifice 138 and opening
140 thus integrating the acceleration force with respect to
time. Suitable electrical contacts may be provided on the
guideway and tension bands to indicate the G-level sensed by
the embers 142 and 144 and tension band 146 and the velocity
change measured by members 124 and 126 and tension band 136.

The roller-band
device may reset to its initial position by forcing or pushing
tongue 106 off ledge 150 with screw 152.

Figure 10
illustrates a roller-band accelerometer or G-switch which may
sense one or more G-force levels. The switch shown in Figure
10 includes a pair of adjacent, spool-shaped rotatable members
154 and 156 held under tension between guideway supporting
walls 158 and 160 and end walls 162 and 164 by tension band
166.

Tension band 166 may
include a rectangular cutout 168 as shown, similar to cutout
60b in Figure 3b along a substantial portion of the band
leaving a pair of outer band portions which supports members
154 and 156 their respective rim portions 170 and 172. Since
the outer band portions have equal dimensions at each contact
line, the tension band does not contribute force biasing to
the switch. The tension band may be fastened with suitable
fastening means at diagonally opposing ends of the guideway as
discussed previously. The band may be fabricated with separate
longitudinally oriented and insulated conductors (not shown:
see Figure 4a) along each outer portion by conventional
laminating techniques and the band folded around the outside
of end wall 164 to provide two sets of conductors which when
connected together by the action of the switch may form
separate complete circuits with a measuring or utilization
means (not shown) which may be connected to the exposed
interrupted conductors in a conventional manner. For instance,
the portion of the tension band folded around end wall 164 may
be plugged directly into a suitable connector or circuit board
and thus make contact with the interrupted conductors and
complete the circuit with measuring means.

Since the roller
appear to be rolling generally about the contact lines at any
given point along the guideway, displacement or forces may be
applied or decreased infinitely in a mechanism by coupling or
connecting the mechanism to any point on any radius of the
roller, either above or below the roller axis and either
within or without the roller diameter, depending on the
desired result. Thus, a tension spring 178 may be fastened
between the rims of rotatable member 156, as shown, and end
wall 162 so as to decrease spring placement and effectively
lengthen the spring. The spring may be fastened to an
initially smaller radius of the rotatable member (such as a
chordal cutout in the outside circumference leaving a
substantial surface of the original circumference) which
radius is increased as the rotatable member rolls so as to
effect increased displacement of the spring at the beginning
of motion and allow the spring to be stored at relatively low
tensions. Tension spring 178 preferably has a linear positive
spring constant. Spring 178 may be fastened to end wall 162
with suitable adjusting means so as to enable the adjustment
of the proper spring tension along the force bias curve. An
adjustable breakaway force level may be provided by adjusting
screw 180.

As the switch shown
in Figure 10 is subjected to an increasing force in the
direction of the arrow which exceeds the preselected breakaway
force, the rotatable members and tension band may roll along
the guideway. As the members and band continue to roll, the
tension spring is stretched, increasing the force bias applied
to member 156. If the force level does not continue to
increase, the members and tension band may reach a stable
balanced position of rest or they may return to the initial
position. If the force level increases sufficiently, the
rotatable members and tension band will roll over electrical
contacts 174 and 176 at preselected force levels and initiate
the measuring or utilization circuits. The tension spring and
positions of contacts 174 and 176 may be adjusted and
calibrated by conventional standard weight techniques.

Figure 11
illustrates a roller-band device which may function as a
substantially frictionless piston in a fluid pump. The
roller-band device in Figure 11 includes a pair of adjacent
rotatable members 182 and 184 held under tension in an initial
position between guideway supporting walls 186 and 188, end
walls 190 and 192 and side walls (not shown) by tension band
194. Tension band 194 preferably has a return force type bias
such as shown in Figure 3b. In order to provide this force
bias, the portions 196 and 198 of tension band 194 which
partially encompass 182 and 184 may be preformed by cold
forming tension band 194 in a generally S-shape with portion
196 having a greater radius of curvature than protion 198.

The travel of
members 182 and 184 and tension band 194 from one end of the
guideway or to the other may be sensed by suitable electrical
contacts or by microswitches 200 and 202 as shown.

For this embodiment,
it is preferable that the rotatable members and tension band
be dimensioned as closely as possible to the inside dimensions
of the side walls so as to form two chambers 201 and 203 on
either side thereof and to prevent fluid or gas leakage around
the ends thereof. Typical spacing may be between 0.0002 and
0.003 inch. A pressurized driving medium may be coupled to
chamber 201 through end wall 190 by fluid inlet 204 which may
be controlled or valved by switches 200 and 202 and valve 205.
Valve 205 may be any suitable multiposition valve which in one
position may pass driving fluid (either gas or liquid) into
chamber 201 and in a second position may close off inlet 204
and vent chamber 201 to ambient pressure. End wall 192
includes a pumping fluid or gas outlet includes a pumping
fluid or gas outlet 206 which may be controlled or valved with
a suitable pressure release or check valve 208. Wall 188
includes a pumping fluid or gas inlet 210 which may be
controlled or valved with a suitable pressure sensitive or
check valve 212.

Assume that the
roller-band device in Figure 11 is in its initial position, as
shown, that valve 212 is open allowing pumping fluid or gas
into chamber 203, that switch 200 is energized which in turn
has opened valve 205 to driving fluid inlet 204 and that
switch 202 is deenergized. As the driving fluid enters and
fills chamber 201, rotatable members 182 and 184 and tension
band 194 may be driven down the guideway, deenergizing switch
200 As the members and band travel down the guideway, the
pressure in chamber 203 is increased, closing pressure
sensitive valve 212 and opening valve 208 allowing the pumping
fluid to pass through outlet 208. When the members and band
reach the end of the guideway, switch 202 may be energized,
thus opening valve 205 to ambient pressure allowing the
driving fluid or gas to escape from chamber 201. Tension band
194 may then drive the members and band back to their initial
position, lowering the gas or fluid pressure in chamber 203,
thus closing valve 208 and opening valve 212. Switch 202 may
be turned off and switch 200 turned on, starting the pump
stroke again.

The device shown in
Figure 11 may also be used as a piston in an engine, actuator
or shock absorber.

Figure 12 illustrate
a roller-band device having unequal diameter rotatable
members. The device includes a pair of adjacent rotatable
members 214 and 216 held under tension between guideway
supporting walls 218 and 220 and end walls 222 and 224 by
tension band 226. Tension band 226 may have any desired force
biasing and the relative sizes of members 214 and 216 may be
selected depending on the particular application of the
device.

As the rotatable
members and tension band roll along the guideway, member 214
may turn at a greater rate of speed than that of member 216
depending on the ration of the diameters of the members.
Roller band devices have been constructed with speed change
ratios as high as 200 to 1.

A doubly integrating
accelerometer may be provided by rigidly attaching a pair of
large diameter flywheels (not shown) to member 214, using the
inertia of the flywheels as an integrating force so that the
linear motion of the members and tension band represent the
motion of a carrying vehicle. This device may also act as a
rack and pinion wherein one member functions as a rack and the
other functions as a pinion.

Figure 13
illustrates a roller-band device which may function as an
electrical potentiometer and function generator. The device
shown includes a pair of hollow rotatable members 226 and 228
held under tension between guideway supporting walls 230 and
232 and end walls 234 and 236 by tension band 238. Tension
band 238 may have any desired force biasing depending on the
particular application of the potentiometer or function
generator. Wall 230, in this embodiment includes an outer
guideway wall 240, a first resistance wire 242 and a second
resistance wire 244 laterally disposed from resistance wire
242, and an insulating layer 246 separating the resistance
wires from wall 240. Tension band 238, which may be made of a
suitable electrical conductive material, rolls directly along
resistance wires 242 and 244. Resistance wires 242 and 244 may
be connected to a suitable power source (not shown) and
utilization means (not shown).

As the rotatable
members and tension band roll along the guideway, tension band
238 acts as a moving electrical short at its contact line with
the resistance wires, thus establishing a varying resistance
loop.

If one or both of
the resistance wires 242 and 244 is bent or curved with
respect to the other wire, the linear movement of tension band
238 along the resistance wires may generate any arbitrary
function of resistance with respect to time or other variables
linked to roller displacement.

It will be apparent
that one or the other wires 242 or 244 may be a good
conductive material and that one wire may be placed along each
guideway supporting wall rather than on the same wall as
shown.

Figure 14
illustrates a roller band force amplifier or impacting device
which is capable of producing large normal forces from a given
input force. The device includes a pair of adjacent rotatable
members 250 and 252 held under tension in an initial position
as shown between an upper guideway supporting wall 254 which
extends the entire length of the device, a first lower
guideway supporting wall 256 which extends only a portion of
the length of the device and end walls 258 and 260 by a
tension band 262. A second lower guideway wall 264, which is
separated from wall 254 by a greater distance than wall 256,
extends from the end of wall 256 the remaining length of the
device to end wall 260. The end portion 257 of wall 256 thus
provides an abrupt or step increase in guideway supporting
wall spacing.

Tension band 262
maybe fastened at one end to upper wall 254 adjacent end wall
256 and fastened to tension spring 266. Tension spring 266 may
be fastened at its free end to a convenient fixed point such
as the outside of wall 256. Tension spring 266 introduces the
necessary tension forces to tension band 262. Tension band 262
may include suitable force biasing, such as described above,
depending on the application of the device.

The diameters of
rotatable members 250 and 252 are selected so that their
combined diameters is at least slightly greater than the
distance between walls 254 and 264 (the closer the dimension,
the higher the force amplification). The rotatable members may
be a solid or hollow cylinder but in order to decrease any
inertial delays from the "flywheel effect", the members, as
shown with respect to member 250 may be made of a heavy center
core 268 concentrically surrounded by a lighter tubular member
270. Core 268 may be made of a material such as a sintered
tungsten alloy while member 270 may be made of a material such
as aluminum.

When the rotatable
members and tension band are subjected to a force, such as a
G-force, in the direction of the arrow, the members and band
travel down the guideway between walls 254 and 256. When a
member 252 reaches end portion 257 and sees the step increase
in wall spacing, the force in tension band 262 provided by
spring force in tension spring 266 may be imparted to member
252 as kinetic energy. Member 250 is pulled back to the
position shown by dotted lines and member 242 impacts on wall
264. In addition to the very large direct mechanical advantage
achieved by the spring combination and nearly vertical
disposition of the rollers at impact, this device also makes
it possible to recover the very high forces associated with
the substantially instantaneous stopping of the rollers.
Substantially all the kinetic energy imparted to the rollers
is recovered as the rollers impact and are locked in place by
friction.

A firing pin 272 and
detonator 274 may be positioned on wall 264 aligned with
member 252 so that the impact of member 252 may fire the
detonator. The detonator may be operably connected to some
utilization means such as an explosive, a pyrotechnic in a
thermal battery or the member could perform directly dome
mechanical functions such as forming or shearing materials.

Figure 15
illustrates a mechanism for supporting heavy loads using a
plurality of groups of rotatable members. As shown in Figure
15, a load 176 may be supported between a pair of roller-band
devices 278 and 280. Since each device is essentially
identical, only device 278 will be described in detail.

In device 278, a
plurality of rotatable members, each group including a pair of
adjacent rotatable members 282 and 284, may be held under
tension between guideway walls 286 and 288 and end walls 290
and 291 by a tension band 292. Tension band 292 may be
fastened at either end to walls 286 and 288 in the same manner
as described above after being threaded around each of the
members 282 an 284 of each pair as shown in generally S-shaped
configuration. A group of idler roller 294 may then be
inserted between tension band 292 and the load 276 adjacent
and between members 284 in slot 296 in wall 288.

The load is
supported between devices 278 and 280 by a second group of
idler rollers 298 in a similar slot in device 280.

Any number of groups
of rotatable members may be used depending on the size of the
load. Additional load bearing capability may be obtained by
using one or more additional rows of rotatable members aligned
with each group of members 282 and 284 and reverse looping the
tension band along each row in the same manner as shown as
long as the summation of diameters of the rotatable members in
any one group is greater than the distance between the
supporting walls 286 and 288.

The device 332 shown
in Figure 16 includes a guideway having an outer tubular
member or wall 334 and an inner concentric circular member or
wall 335, which may be a cylinder as shown. A plurality of
groups of rotatable members 336 and 338 is positioned within
the guideway formed by walls 334 and 334 and held in place by
continuous tension band 340. Tension band 340 is held under
tension and away from walls 334 and 335 by the restraining
force created between the rotatable members and the guideway
walls. Each rotatable member is shown as a hollow cylinder.

Roller-band device
332 may be a bearing used to support a rotating shaft
represented by circular wall 336 of the guideway. Since
tension band 340 maintains the axes of the rotatable members
in parallel, the normal end effects and losses in conventional
roller bearings is obviated. Further, since there is little or
no relative motion between contiguous parts of the roller-band
device, the device substantially exhibits only pure rolling
motion.

The roller-band
devices shown in Figures 6-14 above may be easily constructed
using microminiature modular techniques by making a wide range
of devices with the same general modular components. These
devices may use a guideway formed from stock extruded square
tubing having cross section dimensions of about 0.25 x 0.25
inch and lengths from about 0.312 to 1.25 inches with an
average volume of about 0.5 cubic inch. Rollers may be
fabricated having diameters ranging from 0.115 to 0.205 inch
which may then be paired to perform any desired function. Some
rollers may be bored with a standard orifice as shown in
Figure 9 which may then be fitted with conventional
obstructions to create a desired leakage and damping. Standard
force bias type tension bands (see Figure 3) and multiple
conductor bands (see Figure 4) may be produced and desired
force biasing applied by photographic etching or other
conventional techniques.

These devices may be
built to operate from a breakaway force between 0.002 G to
7,000 G and measure G-seconds over a range of from about 0.25
G-second to 200 G-seconds. The devices may also perform a wide
range of functions or detect a complex force pattern and
generate multiple indications thereof within an extremely
small package and with a relatively small number of parts.

A roller-band device
may operate at substantially lower friction than comparable
devices under the same operating conditions (in some cases
having a coefficient of friction as low as 0.0001). Thus under
many extreme operating conditions where lubricants cannot
normally be used, the devices can operate with a minimum of
wear and friction. If it is desired and conditions permit,
lubricants may be used to decrease still further the rolling
friction losses.

Because these
devices exhibit exceedingly low coefficients of friction and
may substantially eliminate surface roughness losses which in
many instances where used in prior condition sensing devices
to effect good electrical contacts, these devices may employ
high normal forces between electrical contacts without
seriously degrading accuracy of the device.

While for purposes
of illustration various features are shown in different views,
it will be clear that the majority of features may be embodied
into a single device. It will also be understood that various
changes in the details, materials and arrangements of the
parts, which have been described herein and illustrated in
order to explain the nature of the invention, may be made by
those skilled in the art within the principles and scope of
the invention as expressed in the appended claims

---

  

**Rolamite Patents**

**Class 200 / Subclass 503 --- Rolamite-type:** Subject
matter comprising a flexible roller band or spring band device
wherein at least a pair of rotatable roller contact members are
disposed within a switch housing and the flexible resilient band
is convoluted around the roller contact members in S-shaped
configuration so as to maintain the roller axes parallel as they
move within the housing when actuated.  
  
**US5272293 -- Rolamite Acceleration Sensor [ [PDF](US5272293A.pdf) ]**A rolamite acceleration sensor which has a failsafe feature
including a housing, a pair of rollers, a tension band wrapped
in an S shaped fashion around the rollers, wherein the band has
a force-generation cut out and a failsafe cut out or weak
portion. The failsafe cut out or weak portion breaks when the
sensor is subjected to an excessive acceleration so that the
sensor fails in an open circuit (non-conducting) state
permanently.  
  
**US5178264 -- Rolamite Sensor [ [PDF](US5178264A.pdf) ]**A rolamite sensor for use in sensing deceleration of a
vehicle includes two separate electrical circuits for actuating
one or more occupant restraints such as air bags. The sensor has
a base mounted on a chassis and a cover welded to the chassis to
enclose the base. One surface of the base acts as a guide
surface for a roller. A pair of thin metal bands are wrapped
around the roller. The ends of the bands are fixed to the base.
The roller is rollable on the guide surface under an applied
force to cause the bands to engage firing contacts to complete
the electrical circuits. The roller has a pair of spaced apart
tubular metal caps supported on a non-conductive insert. Each
band is welded to a respective one of the conductive metal caps
of the roller.  
  
**US5036304 -- Rolamite Sensor [ [PDF](US5036304A.pdf) ]**A rolamite sensor for use in sensing deceleration of a
vehicle includes two separate electrical circuits for actuating
two occupant restraints such as air bags. The sensor has a
molded plastic base mounted on a metal chassis and a metal cover
welded to the chassis to sealingly enclose the base. One surface
of the base acts as a guide surface for a roller. A pair of thin
metal bands are wrapped around the roller. Each band is fixed at
one end to the base and at the other end to a J-shaped tensioner
underneath the base. The roller is rollable on the guide surface
under an applied force to cause the band to engage firing
contacts to complete the electrical circuits. An optical
electromagnet may be fixed to the chassis without increasing the
overall size of the sensor. The electromagnet is selectively
operable to attract the roller to test the sensor by completing
the electrical circuits. The electromagnet includes a
ferromagnetic core and a coil wound directly on the core. The
roller has a ferromagnetic insert formed in a dumb-bell shape,
that is, having a larger cross-section at its ends than in the
middle to increase the attractive force of the electromagnet
without significantly increasing weight and thus inertia of the
roller. The chassis and the cover may be made of a ferromagnetic
material to shield the sensor from external magnetic fields.  
  
**US4116132 -- Inertial Sensors [ [PDF](US4116132A.pdf) ]**The sensor includes a linearly movable mass including two
sections and spring means urging one of the sections into
operative engagement with means including an actuating element.
The sensor also includes means releasably securing the two
sections together and means releasing the securing means when
the two sections have moved a predetermined distance against the
urging of the spring. The two sections may be rollers of a
rolamite unit. A flexible band extends around a portion of the
two rollers. One example of a use for such a sensor is in an air
bag safety restraint system.  
  
**US3859488 -- Point Contact Roller Band Switch [ [PDF](US3859488A.pdf) ]**A roller band electrical switching mechanism wherein one or
both of the rollers serves as a movable contact, the roller or
rollers functioning as a contact being supported and guided
directly by the case. The roller support and guide surfaces, or
races, of the case are concavely curved and incorporate fixed
contacts which have exposed surfaces which lie flush with the
roller guide surface of the case. The roller, with its ends in
substantial rolling point engagement with the races, closes or
opens electric circuits as it rolls along the guide surfaces.
The roller band in most cases does not touch the case. By thus
suspending the roller so that it can serve as a movable contact,
exerting great localized pressure on embedded contacts flush
with the roller support surface while producing minimal
switching friction, a substantial increase of switching quality
and utility is achieved.  
  
**US3848695 -- Apparatus for Controlling an Inflatable Safety
Device [ [PDF](US3848695A.pdf)
]**Apparatus for controlling an inflatable safety device for
restraining an occupant of a motor vehicle during a crash. The
preferred form includes electrically acuated means for causing
the inflation of the inflatable safety device, first and second
acceleration-responsive switches positioned on the vehicle's
radiator or its support structure, a third
acceleration-responsive switch positioned in the vehicle's
passenger compartment, and a thermal cut-off device for
disconnecting the inflation control apparatus from the vehicle's
source of electrical energy if either of the first or second
acceleration-responsive switches is closed for a predetermined
length of time. The third switch is responsive to acceleration
impulses of predetermined magnitudes and durations less than
those to which the first and second switches are responsive. The
thermal cut-off device includes a fusible element and has a
resistance wire coiled around it to melt the fusible element.
The acceleration-responsive switches are of the roller-band
type.  
  
**US3812726 -- Velocity Responsive Apparatus [ [PDF](US3812726A.pdf) ]**A velocity measuring apparatus is provided with means for
increasing the rotational moment of inertia of a roller which
displaces a band of electroconductive material against a
preselected resisting force and into contact with a conductive
member. The extent of displacement necessary for contacting the
band with the conductive member is thereby decreased without
changing the magnitude of the preselected resisting force. The
velocity measuring apparatus is highly reliable in operation and
is sufficiently compact to be economically installed in a
limited space.  
  
**US3773344 -- Ski Bindings**Ski binding units for fastening a ski boot at the toe and
heel of the boot. The toe binding unit applies cantilever
loading to the toe of the boot through an abutment which
overlaps the toe of the boot. The heel binding unit supports the
heel on roller bearings and yieldably clamps the heel against
the bearings by means of a snap action spring blade. The heel
unit releases the heel of the boot laterally while the toe
pivots about the toe unit, when a predetermined lateral force is
applied. The heel unit is capable of releasing the boot
vertically when predetermined forces are applied to the
respective units. The heel binding includes a clamping roller
that engages a cam surface on the heel of the boot. Lateral
displacement of the heel stresses the blade progressively unitl
it snaps over to release the heel.  
  
**US3726040 -- Firearms Trigger Mechanism [ [PDF](US3726040A.pdf) ]**A gun trigger mechanism in which a spring loaded striker is
held in a cocked position by a sear. The sear engages a sear
notch on the striker. The sear includes a roller that releases
the striker by rolling relative to the notch. The trigger is
connected with the roller so that movement of the trigger causes
the roller to roll along the striker notch until the striker is
released from the cocked position.  
  
**US3691871 -- Rotary Motion Transmitting Apparatus [ [PDF](US3691871A.pdf) ]**Apparatus for transmitting rotary motion between two
relatively movable members. The apparatus includes an elongated
thin flexible element in the form of a band arranged in a pair
of adjoining alternate loops with a roller confined within each
of the loops. The rollers roll along a circular path as the band
progressively passes around the rollers. The rollers and the
band are supported on a cylindrical guide surface and the rate
of motion of the components of the apparatus relative to each
other permits a high degree of amplification or reduction
between input and output elements. As an alternative usage, the
apparatus readily lends itself to two inputs in a manner
equivalent to a geared differential.  
  
**US3688063 -- Crash Sensing Switch [ [PDF](US3688063A.pdf) ]**There is described a crash switch which can sense
acceleration forces that operate for some period of time such
that the product of acceleration and time exceeds some
predetermined level before the switch is actuated. The switch
utilizes rollers supported by a band wrapped around the rollers,
in which movement of the rollers along the band actuates switch
contacts to signal movement of the rollers over a predetermined
distance. In one modification, change in the center of gravity
of the rollers is used to shift the direction of maximum
sensitivity to the accelerating force. A single calibration
adjustment, by shifting the initial position of the rollers,
controls both the level of acceleration force required to move
the rollers and the acceleration-time product level required to
trigger the switch to the nominal design levels.  
  
**US3687470 -- Ski Bindings [ [PDF](US3687470A.pdf) ]**Ski binding units for fasting a ski boat at the toe and heel
of the boat. The toe binding unit applies cantilever loading to
the toe of the boot through an abutment which overlaps the toe
of the boot. The abutment is hinged to the base which is secured
on the ski. A shear wire temporarily prevents the abutment from
swinging vertically relative to the base. The heel binding unit
supports the heel on roller bearings and yieldably clamps the
heel against the bearings by means of a snap action spring
blade. The heel unit releases the heel of the boot laterally
while the toe pivots about the toe unit, when a predetermined
lateral force is applied. Both the toe unit and heel unit are
capable of releasing vertically when predetermined forces are
applied to the respective units.  
  
**US3686965 -- Snap Action Apparatus [ [PDF](US3686965A.pdf) ]**A pair of thin flexible bands are arranged in a loop with
one band being on the inside of the loop and the other band
being on the outside of the loop. The inner band is resiliently
flexed in a lobe arching away from the outer band, and the bands
are secured together adjacent the ends of the loop. The bending
moments in the inner band normally urge the lobe to progress
toward one end of the loop. By changing the curvature of the
loop, the bending moments in the inner band are changed and the
lobe snaps over to the opposite side of the loop.  
  
**US3671052 -- Ski Bindings [ [PDF](US3671052A.pdf) ]**Ski bindings for gripping the heel and toe portion of a ski
boot. The heel and toe bindings are separate units which release
by a snap action in response to the application of a
predetermined force through the heel or toe of the boot to the
respective bindings. A snap action blade provides the force for
resisting lifting movement of the heel of the boot and for
resisting swinging movement of the toe of the boot relative to
the ski. Both the release force and the degree of movement
permitted by the respective bindings is adjustable.  
  
**US3670579 -- Differential Band Cyclic Apparatus [ [PDF](US3670579A.pdf) ]**The apparatus includes a guide surface and a thin,
resiliently flexible endless band. The guide surface provides a
continuous cyclic path for the band. The length of each cycle of
the guide surface is substantially less than the cyclic length
of the band and the band is arched away from the guide surface
in a lobe. Portions of the band on opposite sides of the lobe
frictionally engage the surface to prevent the lobe from
collapsing. The lobe is capable of progressing along the band to
displace the lobe relative to the guide surface. Each cycle of
the band relative to the guide surface advances the band a
predetermined distance along the guide surface.  
  
**US3667394 -- Rolamite Safety & Arming Mechanism [ [PDF](US3667394A.pdf) ]**An inertial operated fuzing and arming mechanism having two
telescoping encasing members and a pair of rollers held within
said encasing members and a pair of rollers held within said
encasing members by a plurality of S-shaped flexible bands, each
band engaging different diameter portions of the rollers and the
ends of the bands being attached to the inside of said encasing
members. A detonator and explosive are associated with one of
said encasing members and one of the rollers and the other
encasing member has an aperture therein so that when said two
encasing members and said roller are aligned, the fuze is
activated to detonate the explosive.  
  
**US3651732 -- Piano Actions [ [PDF](US3651732A.pdf) ]**A piano action for transmitting motion individually from a
piano key to a hammer which strikes the corresponding string.
The hammer is supported on a roller for swinging toward and away
from the piano string. A guide bar supports the roller and a
thin flexible band extending around the bar and the roller
transmits motion from the key to the roller. The hammer, roller
and guide bar are mounted on an individual frame which allows
the piano action foe each string position to be installed and
removed separately. The piano action also includes a toggle
device which controls the operation of a backcheck and includes
a damper for the string that is operated in coordination with
the motion of the hammer.  
  
**US3643049 -- Roller-Band Device [ [PDF](US3643049A.pdf) ]**A roller-band device which utilizes a roller with a flexible
band encircling it. The band has two sections which are
electrically insulated from each other and the roller is
nonconductive but has one or more conductors extending axially
along its surface and disposed so that, in certain positions of
the roller and band, the two sections of the band are bridged
and an electrical circuit is completed therebetween and, in
other positions of the roller, the electrical circuit is broken
between the two sections of the band. One section of the band
may include a plurality of legs, each electrically insulated
from each other, and with each of the legs being bridged by the
conductor means in different positions of the roller and band.
In another embodiment the conductor means is arranged so that a
circuit is completed to all of the legs simultaneously upon the
roller and band moving to a predetermined position. A keyboard
arrangement is disclosed wherein a plurality of switches of this
type are utilized together, each with a different combination of
legs connected into the output circuit to provide a coded signal
to a device such as used in computer periphery equipment. Also
disclosed is a roller-band device of the type described above
having a unique actuating means, especially useful in connection
with a keyboard switch, which includes a force-amplifying
connection between the manual actuator and the roller and band
and which provides a breakaway action as the manual actuator is
operated.  
  
**US3643048 -- Roller-Band Device [ [PDF](US3643048A.pdf) ]**A roller-band device which utilizes a single roller with a
flexible band encircling it and having its ends extending
generally in opposite directions therefrom. The band has
complimentary cutout and solid portions, preferably a pair of
spaced leg portions at one end of the band and a tongue portion
disposed between and having a width somewhat less than the space
between the two leg portions at the other end whereby the band
is wrapped around the roller and the tongue passes between the
spaced legs without touching them. The roller and band are
movable together along a predetermined path and may be used for
performing various electrical switching functions. Opposite ends
of the band decline from the plane on which the roller moves and
form an acute angle therewith so that a high-contact force is
obtained between contact surfaces on the roller and on the
frame. A unique frame and housing means renders the device
easily assembled and calibrated and then encloses the device.
Also disclosed is a roller-band device with multiple rollers
spaced along a common band.  
  
**US3641296 -- Roller-Band Device with Diverging Walls Biasing
Means [ [PDF](US3641296A.pdf)
]**A roller-band device of the type wherein a pair of rotatable
members are disposed within a housing and a flexible, resilient
band is convoluted around the members in S-shaped configuration
to maintain their axes parallel as they move within the housing.
The housing is comprised of two nonparallel planar sections
which diverge as one end of the housing is approached. Since the
inherent tendency of the flexible band to return to a linear
position decreases with divergence of the planar sections, the
two rotatable members are always biased in the direction of
divergence of the wall sections. An end wall, which is spaced
from the point of closest proximity of the planar sections, is
bendable about a fulcrum point and the flexible band is trained
around this wall, under tension, when the rotatable members are
disposed adjacent thereto. A control band element is coupled to
the flexible band for shifting the rollers toward the end of the
housing where the opposed planar sections converge. As the
members are moved away from the pivotal end wall, tension on the
flexible band increases as the end wall is biased about its
fulcrum point in the direction of movement of the members.
Return movement of the members in the direction of divergence of
the planar sections decreases the tension on the flexible band
but movement of the end wall assures that the flexible band
remains taut.  
  
**US3636284 -- Electrical Snap Action Switch Apparatus [ [PDF](US3636284A.pdf) ]**Two related applications of Donald F. Wilkes entitled
respectively "Snap Action Apparatus" Ser. No. 717,114, filed
Mar. 29, 1968 and "Magnetically Operable Switching Apparatus,"
Ser. No. 717,113, filed Mar. 29, 1968 now U.S. Pat. No.
3,543,595 are being filed concurrently herewith. Both disclose
related subject matter, and the disclosures thereof are
incorporated herein by reference. BACKGROUND OF THE INVENTION --
This invention relates to electrical contact making and breaking
apparatus of the snap-action type. It is concerned particularly
with apparatus in which movable contacts are provided on
elements of thin resilient sheet material and in which the sheet
material is deformed elastically in effecting the snap-actions
desired for contact making and breaking.   
  
**US3639018 -- Tapered Roller Bearing [ [PDF](US3639018A.pdf) ]**A tapered roller bearing assembly in which load-bearing
rollers are spaced apart from each other by idler rollers. The
idler rollers are supported at their opposite ends in bearing
races which are mounted on the outer bearing race for the load
rollers. A shoulder adjacent the inner bearing surface for the
load rollers cooperates with a conical surface on the end face
of the load rollers to urge the load rollers to remain in
alignment as they progress around the bearing races.  
  
**US3560904 -- Electric Coils [ [PDF](US3560904A.pdf) ]**An electric coil in which the turns of the conductor are
wound in multiples, rather than in single strands. The conductor
is printed or otherwise provided on a web of insulating
material. The conductor is arranged in a spiral pattern around a
central opening in the web. The web on opposite sides of the
opening is wound in opposite directions so that the flux
produced by current in the conductor is additive when the
windings have a common central axis.  
  
**US3555909 -- Meter Movement [ [PDF](US3555909A.pdf) ]**In meter movements wherein a pointer moves across a scale in
response to relatively small deflections of a Bourdon tube,
bellows or the like, improved means comprising motion
transferring means operatively connected to the transducer and
connected to the pointer wherein the pointer is rotated relative
to the scale by operation of a frictionless and gearless
mechanism converting the transverse movement of the transducer
to rotation of the pointer.   
  
**US3452309 -- Roller-Band Devices [ [PDF](US3452309A.pdf) ]** A roller-band device of the type disclosed in
Specification 1,181,636 and comprising a plurality of rollers
34, 36 supported by a guideway consisting of walls spaced apart
by a distance less than the summation of the roller diameters
and a flexible band 38 partially encompassing the rollers to
form a linearly-movable cluster, is provided with means 52a to
bias the cluster towards one end of the guideway. The biasing
means comprises a spring, which may be placed parallel to the
guideway, or at an angle to it (56, Fig. 3d, not shown).
Alternatively, it may be attached to the flexible band (Figs.
7a, 8a, not shown) or across the rollers (Fig. 9a, not shown) or
across the rollers (Fig. 9a, not shown). Figs. 10 and 11 (not
shown) illustrate a magnetic latching relay comprising a
solenoid (94) acting on the roller (82) in opposition to the
spring (96), and electrical contacts (98, 100)  
**US3452175 -- Roller-Band Devices [ [PDF](US3452175A.pdf) ]**  
The present invention relates to a rollerband device which
substantially eliminates or minimizes sliding friction; the
device having a plurality of rotatable members in a guideway
with generally equidistantly spaced walls, with each wall
supporting and restraining one of the rotatable members and
separated from the other less than the summation of the
diameters of the rotatable members, and a flexible band between
the guideway walls having a portion disposed between the
rotatable members at least partially encompassing at least one
member, the band holding the members with generally parallel
axes and providing rolling motion between each element of the
device.   
  
**US3161736 -- Omni-Directional Switch [ [PDF](US3161736A.pdf) ]****US2997883 -- Acceleration Integrating Means [ [PDF](US2997883A.pdf) ]****US3548138 -- Rolamite Pushbutton Switch [ [PDF](US3548138A.pdf) ]****US3543595 -- Snap Action Apparatus = US3671052 -- SKI
BINDINGS    [ [PDF](US3671052A.pdf) ]****US3539742 -- Electrical Switches [ [PDF](US3539742A.pdf) ]****US3479624 -- Magnetically Operable Switching Apparatus [
[PDF](US3479624A.pdf) ]****US3471668 -- Roller-Band Devices [ [PDF](US3471668A.pdf) ]****US3672325 -- Transducer with Visible Output [ [PDF](US3672325A.pdf) ]****US3621726 -- Pressure Gauges [ [PDF](US3621726A.pdf) ]****US3617669 -- Rolamite Apparatus [ [PDF](US3617669A.pdf) ]****US3605546 -- Roller Valve Device [ [PDF](US3605546A.pdf) ]****US3576295 -- Linear Recirculating Bearing [ [PDF](US3576295A.pdf) ]****US3567881 -- Roller-Band Inertial Switch [ [PDF](US3567881A.pdf) ]****US4985604 -- Rolamite Sensor [ [PDF](US4985604A.pdf) ]**  
  


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