Rolamite

The Rolamite bearing has very little friction

A Rolamite is a technology for very low friction bearings developed by Sandia National Laboratories in the 1960s.[1] 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, thermostats, valves, pumps, and clutches.[2]

Development

The Rolamite was invented by Sandia engineer Donald F. Wilkes and was patented on June 24, 1969.[3] 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.[1] It became known as Rolamite.

The Rolamite uses a stressed metal band and counter-rotating rollers within an enclosure to create a linear bearing device that loses very little energy to friction. An article in Popular Mechanics claims it is the only basic mechanical invention of the 20th century.[4] Tests by Sandia indicated that Rolamite mechanisms demonstrated friction coefficients as low as 0.0005, an order of magnitude better than ball bearings 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.[5]

A video of a Rolamite in operation, to serve as a warhead safety-switch accelerometer, is available.[6]

See also

• Scrollerwheel

References

Linear

1. Blau, Peter J. (2008). Friction Science and Technology: From Concepts to Applications, Second Edition. Boca Raton, FL: CRC Press. pp. 367. ISBN 978-1-4200-5404-0.
2. Popular Science. Bonnier Corporation. 1968. p. 96.
3. Wilkes, Donald F. (June 24, 1969). "US Patent #3,452,175: Roller-Band Devices". Rex Research. Retrieved 2007-12-11.
4. Norman, Carlisle (February 1968). "The Amazing Rolamite – It Opens the Door for 1000 Inventions". Popular Mechanics.
5. Tseytlin, Yakov M. (2007-03-20). Structural Synthesis in Precision Elasticity. New York: Springer Science+Business Media. p. 249. ISBN 978-0-387-25156-1.
6. Always/Never: The Quest for Safety, Control, and Survivability - Part 2. Sandia National Labs. 16 June 2015. Event occurs at 19:30.

• Nelson, Robert A. "Rolamite". Rex Research. Retrieved 2007-12-11. {{cite web}}: External link in |publisher= (help)
• 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

• Brinkman, Erik. "ScrollerWheel Rotary Rolamite". Erik Brinkman. Retrieved 2008-07-12. {{cite web}}: External link in |publisher= (help)

External links

• Compilation of Rolamite information and articles Including pictures and applications.

Linear

• Video of a homemade rolamite

Rotary

• U.S. Patent #5,462,363