Goal
Provide an almost frictionless mechanical bearing and motion mechanism for switches, valves, pumps, clutches, and other devices, reducing wear and lubrication needs.
Problem
High friction and wear in conventional bearings and mechanical linkages, requiring lubrication and causing energy losses.
Concept Summary
The Rolamite consists of an S-shaped elastic metal band held under tension with two rollers engaged in a track. As the rollers move, the band rolls without slipping, delivering motion with extremely low friction. Band tension stores elastic energy, and modifications such as slots, bimetallic elements, or varying roller sizes enable snap-action, force bias, speed change, and amplification functions.
Detailed Description
A flexible steel or beryllium-copper band is formed into an S-shape and fixed at its ends under tension. Two rollers are placed on opposite sides of the band within a guiding track. When a roller is pushed, the band unwinds from one roller and winds onto the other, keeping the contact points constant and eliminating slip. The pre-tensioned band supplies the necessary energy for motion, so the device operates with friction typically 1-10 % of the best ball bearings. By cutting slots or varying band geometry, a force bias can be introduced, allowing the rollers to move autonomously or produce snap-action. Different roller sizes create speed-changing ratios, and non-circular rollers enable braking or latching. Materials such as rubber stops, cloth, plastic, or bimetallic strips can be incorporated for additional functions. Prototypes have been built for light-load switches, thermostats, valves, pumps, clutches, and even toy guns, demonstrating versatility across many mechanical applications.
Principles
- Rolling contact without slip
- Elastic potential energy stored in a pre-tensioned band
- Force bias via band slots
- Mechanical advantage through differing roller sizes
- Friction reduction through constant contact points
Scientific Domains
Materials
- Steel band
- Beryllium-copper band
- Metal rollers (steel, beryllium-copper)
- Rubber stops
- Cloth
- Plastic
- Rubber
Mechanisms of Action
- Rolling contact
- Band tension energy release
- Slot-induced bias
- Speed change via roller size differential
Energy Sources
Applications
- Electrical switches
- Thermostats
- Fluid valves
- Pumps
- Clutches
- Speed changers
- Frictionless bearings
- Vibrationless sanders
- Toilet valves
- Odometers
- Variable-speed tool drives
- Toy pellet guns
Claimed Performance
Friction 1-10 % of best ball bearings; band durability >1,000,000 flexures without fatigue; up to 30x valve-closing force; cost reduction estimated at 75 % of traditional mechanisms.
Experimental Evidence
Tests showed friction of an amazingly low order - one to ten percent of that in the best ball and roller bearings of similar capacity. Beryllium-copper bands showed no sign of metal fatigue after 1,000,000 flexures.
Replication Status
Multiple prototypes built and tested by Sandia engineers; variations demonstrated for switches, valves, thermostats, and other devices.
Limitations
- Potential metal fatigue after very high cycle counts
- Limited load capacity compared to conventional bearings
- Requires precise band tensioning for optimal performance
- Material wear if band is not properly selected for environment
