Jewel Bearing - Uses

Uses

The largest use for jewel bearings is in mechanical watches, where their low and predictable friction improves watch accuracy as well as improving bearing life. Manufacturers listed the number of jewels prominently on the watch face or back, as an advertising point. A typical fully jeweled time-only watch has 17 jewels: two cap jewels, two pivot jewels, an impulse jewel for the balance wheel, two pivot jewels, two pallet jewels for the pallet fork, and two pivot jewels each for the escape, fourth, third, and center wheels. In modern quartz watches, the timekeeper is a quartz crystal in an electronic circuit, so accuracy of timekeeping is not dependent on low friction of the mechanical parts, and jewels are not used much.

The other major use of jewelled bearings is in sensitive measuring instruments. They are typically used for delicate linkages that must carry very small forces, in instruments such as; galvanometers, compasses, gyroscopes, gimbals, and turbine flow meters. Bearing bores are typically less than 1 mm and typically support loads of under the weight of 1 gram, although they are made as large as 10 mm and support loads up to about the weight of 500 g.