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{{short description|Low friction bearing technology}}
[[File:Rolamite.svg|thumb|320px|The Rolamite bearing has very little friction]]
'''Rolamite''' is a technology for very low [[friction]] [[Bearing (mechanical)|bearings]] developed by [[Sandia National Laboratories]] in the 1960s.<ref name=":0">{{Cite book|title=Friction Science and Technology: From Concepts to Applications, Second Edition|last=Blau|first=Peter J.|publisher=CRC Press|year=2008|isbn=978-1-4200-5404-0|location=Boca Raton, FL|pages=[https://archive.org/details/melancholyfateof0000prit/page/367 367]|url=https://archive.org/details/melancholyfateof0000prit/page/367}}</ref> It is the only elementary machine discovered in the twentieth century and can be used in various ways such as a component in switches, [[Thermostat|thermostats]], valves, pumps, and [[Clutch|clutches]], among others.<ref>{{Cite book|url=https://books.google.com/books?id=lSYDAAAAMBAJ&q=rolamite+friction+bearing&pg=PA96 |title=Popular Science|last=Corporation|first=Bonnier|date=1968|publisher=Bonnier Corporation|pages=96|language=en}}</ref>

==Development==
The Rolamite was invented by Sandia engineer Donald F. Wilkes and was patented on June 24, 1969.<ref>{{cite web|last=Wilkes|first=Donald F.|title=US Patent #3,452,175: Roller-Band Devices|date=June 24, 1969|publisher=Rex Research|url=http://www.rexresearch.com/wilkes/1wilkes.htm#usp|access-date=2007-12-11}}</ref> It was discovered 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.<ref name=":0" /> 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. One source claims it is the only basic mechanical invention of the 20th century.<ref>{{cite news |first=Carlisle |last=Norman |title = The Amazing Rolamite – It Opens the Door for 1000 Inventions |work=[[Popular Mechanics]] |date=February 1968}}</ref> Tests by Sandia indicated that Rolamite mechanisms demonstrated [[friction coefficient]]s as low as 0.0005, an order of magnitude better than [[ball bearing]]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.<ref>{{Cite book|title=Structural Synthesis in Precision Elasticity|last=Tseytlin|first=Yakov M.|date=2007-03-20|publisher=Springer Science+Business Media|isbn=978-0-387-25156-1 |location=New York|pages=249}}</ref>

A video of a Rolamite in operation, to serve as a warhead safety-switch [[accelerometer]], is available.<ref>Youtube. ''Declassified NUCLEAR WEAPONs Safety Control & Survivability Pt 2''. 1h23m20s. Alternatively, ''Always/Never: The Quest for Safety, Control, and Survivability - Part 2'' 19.30, released by Sandia Labs.]</ref>

==See also==
*[[Scrollerwheel]]

==References==
===Linear===
{{reflist}}
* {{cite web|last=Nelson|first=Robert A.|title=Rolamite|publisher=[http://www.rexresearch.com/1index.htm Rex Research]
|url=http://www.rexresearch.com/wilkes/1wilkes.htm|access-date=2007-12-11}}
*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===
* {{cite web|last=Brinkman|first=Erik|title=ScrollerWheel Rotary Rolamite|publisher=[http://erikbrinkman.com/ Erik Brinkman]|url=http://erikbrinkman.com/Scroller/Home.html|access-date=2008-07-12}}

== External links ==
*[http://www.rexresearch.com/wilkes/1wilkes.htm Compilation of Rolamite information and articles] Including pictures and applications.

===Linear===
* [https://www.youtube.com/watch?v=O-1Drlfuoi4 Video of a homemade rolamite]

===Rotary===
*[http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5,462,363.PN.&OS=PN/5,462,363&RS=PN/5,462,363 U.S. Patent #5,462,363]

[[Category:Simple machines]]
[[Category:Bearings (mechanical)]]

{{tech-stub}}

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