ruby jewel bearings used in an Omega mechanical watch movement

A jewel bearing is a bearing which allows motion by running a shaft slightly off-center so that the shaft rolls inside of the bearing rather than sliding. As the shaft rolls, the center precesses. Originally natural jewels were used, such as sapphire, ruby and garnet. In the early 1900s a process to make manmade sapphire and ruby was invented, making jeweled bearings practical at much less expense. Image File history File linksMetadata Download high resolution version (823x638, 441 KB) Summary Detail of a compensation balance wheel, showing blued steel hair spring and bi-metallic split rim balance (from Omega 30t2). ... Image File history File linksMetadata Download high resolution version (823x638, 441 KB) Summary Detail of a compensation balance wheel, showing blued steel hair spring and bi-metallic split rim balance (from Omega 30t2). ... This article needs a whole section regarding the current Omega Models: De Ville, Speedmaster, Seamaster, Railmaster and Constellation; all with their features and uses. ... A bearing is a component used to reduce friction in a machine. ... A shaft can be Look up shaft in Wiktionary, the free dictionary. ... Jewel can refer to Jewel, American singer. ... Sapphire is the single-crystal form of aluminium oxide (Al2O3), a mineral known as corundum. ... Ruby is a red gemstone, a variety of the mineral corundum (aluminium oxide) in which the color is caused mainly by chromium. ... The garnet group of minerals show crystals with a habit of rhombic dodecahedrons and trapezohedrons. ... // Events and Trends Technology Lawrence Hargrave makes the first stable wing design for a heavier-than-air aircraft Orville and Wilbur Wright make the first documented flight in a powered heavier-than-air aircraft Mass production of automobile Wide popularity of home phonograph Panama Canal is built by the United...

Jewel bearings were used widely for mechanical (escapement) watches, where their low and predictable friction improved watch accuracy. A typical mark of watch quality was a note such as "17 jewels". More jewel bearings often meant better precision. Some makers added non-functional or unnecessary jewels to give the impression of accuracy. Some watches had 100 jewels, most of them of no use. A typical "fully jeweled" time-only watch has 2 cap jewels, 2 pivot jewels, an impulse jewel for the balance wheel, 2 pivot jewels, 2 pallet jewels for the pallet fork, and 2 pivot jewels each for the escape, fourth, third and center wheels. Modern electronic watches achieve accuracy entirely separate from the friction of the mechanism, but early quartz watches used jewels to increase battery life, and high-grade quartz watches use jewels to reduce friction and wear. A simple escapement. ... In naval parlance, watches are a timekeeping convention. ... Red arrows indicate the balance wheel on this movement. ... Pallet fork The pallet fork or pallet lever is an integral component of the Lever Escapement of a typical mechanical watch. ... Four double-A (AA) rechargeable batteries In science and technology, a battery is a device that stores energy and makes it available in an electrical form. ... Quartz is amongst one of the most common minerals in the Earths continental crust. ... Friction is the force that opposes the relative motion or tendency of such motion of two surfaces in contact. ...

Today, jewel bearings are used widely in sensitive measuring equipment.

Jewel bearing advantages include high accuracy, very small size and weight, low friction, predictable friction including good temperature stability, ability to operate without lubrication and in corrosive environments. Disadvantages include limited availability/applicability in medium and large bearing sizes and capacities, and friction variations if the load is not axial.

Jewel bearings are typically used for very small applications such as high-precision instruments. Bearing bores are typically less than 1 mm and typically support loads of under 1 gram; large jewel bearings are as large as 10 mm and support loads up to about 500 g. A millimetre (American spelling: millimeter), symbol mm is an SI unit of length that is equal to one thousandth of a metre. ... The gram or gramme, symbol g, is a unit of mass. ...

Historically, jewel pivots were made by grinding. Modern jewel pivots are often made using high-powered lasers, chemical etching, and ultrasonic milling. Etching is an intaglio method of printmaking in which the image is incised into the surface of a metal plate using an acid. ... Cutters for a milling machine. ...

Many bearings have higher starting friction than moving friction. Jewel bearings have very smooth surfaces and so have lower friction variability. Flexure bearings have even lower variability, but also have a more limited range of motion. A flexure bearing is a bearing which allows motion by bending a load element. ...

See also

• chronometer
• clockmaker
• horology
• watch
• watchmaker

A chronometer is a clock accurate enough to be used as a portable time standard on a vehicle, usually in order to determine longitude by means of celestial navigation. ... A clockmaker is an artisan who makes and repairs clocks. ... Horology is the science and study of timekeeping devices. ... In naval parlance, watches are a timekeeping convention. ... This article needs to be cleaned up to conform to a higher standard of quality. ...

External links

• Paul Baillio, "Jewel Bearings Solve Light Load Problems" (PDF)
• A. C. Lawson, "Design Factors for Jewel Bearing Systems" (PDF)
• R. H. Warring, "Calculating Frictional Losses in Jewel Bearing Movements" (PDF)
• American Watchmakers-Clockmakers Institute
• TimeZone.com discussion of watch jeweling