Saturday, December 16, 2006

Nearly frictionless machine

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 paragraph above was taken from (as if you could not have guessed) Popular Science, March 1966. Nifty idea - but perhaps a few years too late to match PopSci's prose ...
... invented by a man named Donald Wilkes, who worked for Sandia Laboratories. It’s a bearing or switch with two rollers and a band around them. The idea is that by using different styles of band and different cutouts in the band, you can get this little device to do different things, to serve as an accelerometer, for example. There was a great fanfare about the Rolamite in the 1960s in both the professional engineering press and media like The New “York Times. Donald Wilkes left his job at Sandia Laboratories, raised money, started Rolamite, Inc., and hired engineers. But the Rolamite turned out to be the second best way to do everything, as one engineer said. And it came at just the time when microprocessors were beginning to do the more sophisticated work that the Rolamite was supposed to handle. At the low end it was too expensive to fabricate to the tolerances needed and still be economical. At the high end it was losing out to the lower and lower costs of solid-state control.

There were just three important exceptions, which go to show how radically unexpected technology can be. One was a postal scale you may still see in garage sales with a kind of twisted band in the front; that has Rolamite geometry in it. The second was the use of Rolamites as accelerometers in thermonuclear weapons, probably because they can’t be spooked by electronic countermeasures. The third one is the automobile air bag. Apparently just about every air bag made has a Rolamite in it, because for an accelerometer at the right tolerance, the Rolamite performs better than any alternative technology.

Air bags were probably the last thing on Wilkes’s mind—they didn’t exist at the time—yet the Rolamite has turned out to be a vital element in their design. Wilkes also told me that his experience with the RoIamite gave him ideas for other inventions with similar geometry.
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