Thrust bearing

Thrust bearing

A thrust bearing is a particular type of rotary bearing. Like other rotary bearings they permit rotation between parts, but they are designed to support a high axial load while doing this.

Thrust bearings come in several varieties.
*"Ball thrust bearings", composed of ball bearings supported in a ring, can be used in low thrust applications where there is little radial load.
*"Tapered roller bearings" consist of small tapered rollers arranged so that their axes all converge at a point on the axis of the bearing. The length of the roller and the diameter of the wide and the narrow ends need to be carefully calculated to provide the correct taper so that each end of the roller rolls smoothly on the bearing face without skidding. These are the type most commonly used in automotive applications (to support the wheels of a motor car for example), where they are used in pairs to accommodate axial thrust in either direction, as well as radial loads. They can support rather larger thrust loads than the ball type due to the larger contact area, but are more expensive to manufacture.
*"Fluid bearings" where the axial thrust is supported on a thin layer of pressurized liquid - these give incredibly low drag.

They are commonly used in automotive, marine, and aerospace applications.

Thrust bearings are used in cars because the forward gears in modern car gearboxes use helical gears which, while aiding in smoothness and noise reduction, cause axial forces that need to be dealt with. André Citroën invented a double helical gear which neutralized the thrust caused by normal helical gears.

One specific thrust bearing in an automobile is the clutch 'throw out' bearing, sometimes called the "clutch release bearing".

Fluid-film thrust bearings were invented by Australian engineer George Michell (pronounced Mitchell) who patented his invention in 1905. Michell bearings contain a number of sector-shaped pads, arranged in a circle around the shaft, and which are free to pivot. These create wedge-shaped regions of oil inside the bearing between the pads and a rotating disk, which support the applied thrust and eliminate metal-on-metal contact.

The small size (one-tenth the size of old bearing designs), low friction and long life of Michell's invention made possible the development of larger propellers and engines in ships. They were used extensively in ships built during World War I, and have become the standard bearing used on turbine shafts in ships and power plants worldwide.

ee also

* Slewing bearing

External links

* [http://www.powerhousemuseum.com/australia_innovates/?behaviour=view_article&Section_id=1080&article_id=10086 The MichellThrust Bearing: a low-friction bearing for thrust shafts] (Powerhouse Museum website)


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Look at other dictionaries:

  • Thrust bearing — Thrust Thrust, n. 1. A violent push or driving, as with a pointed weapon moved in the direction of its length, or with the hand or foot, or with any instrument; a stab; a word much used as a term of fencing. [1913 Webster] [Polites] Pyrrhus with… …   The Collaborative International Dictionary of English

  • thrust bearing — noun a bearing designed to take thrusts parallel to the axis of revolution • Hypernyms: ↑bearing * * * noun or thrust block : a bearing to resist end thrust; specifically : one provided with collars or horseshoe shaped pieces or rollers which… …   Useful english dictionary

  • thrust bearing — A bearing with flanges on its two sides that prevents a shaft such as the crankshaft from moving endwise. In the engine crankshaft assembly these flanges are a close fit to the two sides of the crankpin. If the crankshaft tends to shift one way… …   Dictionary of automotive terms

  • thrust bearing — bearing that is made to absorb thrusts parallel to the axis (Machinery) …   English contemporary dictionary

  • thrust bearing — /ˈθrʌst bɛərɪŋ/ (say thrust bairring) noun a bearing designed to take an axial load …  

  • thrust bearing — Mach. a bearing designed to absorb thrusts parallel to the axis of revolution. [1860 65] * * * …   Universalium

  • thrust bearing — Смотри Подпятник …   Энциклопедический словарь по металлургии

  • Thrust — Thrust, n. 1. A violent push or driving, as with a pointed weapon moved in the direction of its length, or with the hand or foot, or with any instrument; a stab; a word much used as a term of fencing. [1913 Webster] [Polites] Pyrrhus with his… …   The Collaborative International Dictionary of English

  • Thrust plane — Thrust Thrust, n. 1. A violent push or driving, as with a pointed weapon moved in the direction of its length, or with the hand or foot, or with any instrument; a stab; a word much used as a term of fencing. [1913 Webster] [Polites] Pyrrhus with… …   The Collaborative International Dictionary of English

  • Thrust ball bearing — Thrust ball bearings consist of two precision chrome steel washers (ring) and a ball complement spaced by bronze retainer. They can be supplied with or without radius ball grooves in the rings. Thrust bearings are used under purely axial loads.… …   Wikipedia

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