A Rolamite is a technology for very low

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...

bearings developed by

Sandia National Laboratories Sandia National Laboratories (SNL), also known as Sandia, is one of three research and development laboratories of the United States Department of Energy's National Nuclear Security Administration (NNSA). Headquartered in Kirtland Air Force B ...

in the 1960s. It consists of two cylindrical rollers held captive in a channel by an S-shaped metal strip. The strip is under tension, which keeps the rollers pressed together with the strip between them. The rollers move linearly within the channel as they counter-rotate. During the motion each contact surface has the same surface velocity, which results in very low friction. The Rolamite can be used in various ways such as a component in switches,

thermostat A thermostat is a regulating device component which senses the temperature of a physical system and performs actions so that the system's temperature is maintained near a desired setpoint. Thermostats are used in any device or system tha ...

s, valves, pumps, and

clutch A clutch is a mechanical device that allows an output shaft to be disconnected from a rotating input shaft. The clutch's input shaft is typically attached to a motor, while the clutch's output shaft is connected to the mechanism that does th ...

es.

Development

The Rolamite was invented by Sandia engineer Donald F. Wilkes and was patented on June 24, 1969. It was invented while Wilkes was working on a miniature device to detect small changes in the inertia of a small mass. After testing an S-shaped metal foil, which he found to be unstable to support surfaces, the engineer inserted rollers into the S-shaped bends of the band, producing a mechanical assembly that has very low friction in one direction and high stiffness transversely. It became known as Rolamite. The Rolamite uses a stressed metal band and counter-rotating rollers within an enclosure to create a

linear bearing A linear-motion bearing or linear slide is a Bearing (mechanical), bearing designed to provide free motion in one direction. There are many different types of linear motion bearings. Motorized linear slides such as machine slides, X-Y tables, ro ...

device that loses very little energy to friction. An article in ''

Popular Mechanics ''Popular Mechanics'' (often abbreviated as ''PM'' or ''PopMech'') is a magazine of popular science and technology, featuring automotive, home, outdoor, electronics, science, do it yourself, and technology topics. Military topics, aviation an ...

'' claims it is the only basic mechanical invention of the 20th century. Tests by Sandia indicated that Rolamite mechanisms demonstrated

friction coefficient Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...

s as low as 0.0005, an order of magnitude better than

ball bearing A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this ...

s at the time. There are known Rolamite versions that contain two bands that work in reciprocate parallel for more accurate kinematic transmission at the reverse motion. A video of a Rolamite in operation, to serve as a warhead safety-switch

accelerometer An accelerometer is a device that measures the proper acceleration of an object. Proper acceleration is the acceleration (the rate of change (mathematics), rate of change of velocity) of the object relative to an observer who is in free fall (tha ...

, is available.

References

Linear

* *Bishop,James E., (11/27/1973). "Remember the Rolamite? World's 27th-and Newest-'Elementary Mechanism' Still Works, but It Hasn't Revolutionized Technology" ''The Wall Street Journal'' Page 46.

Rotary

External links

Compilation of Rolamite information and articles
Including pictures and applications.

Linear

Video of a homemade rolamite

Rotary

Simple machines Bearings (mechanical) {{tech-stub

Development

See also

References

Linear

Rotary

External links

Linear

Rotary