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What is a Bearing?-2017 China(Guangzhou) Int’l Bearing and Equipment Exhibition
11/8/2016 Bearing and Equipment expo |
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Technically speaking, a bearing is identified as a part of a machine bearing friction, hence the term “bearing”. The most common identification of a bearing is between a rotating part and its housing. To minimize in the damaging effects of the friction, implementations of things like balls and grease. Bearings can restrict the direction of the moving part to the desired direction. Types of manufacturing bearings are explained below.
Types of Bearings Babbitt Bearing
What is a babbitt bearing?
Babbitt bearings have been around for a long time. Babbitt refers to a type of metal-alloy invented in 1839 by Isaac Babbitt. A beneficial characteristic of babbitt metal is its reputation to resist galling – a form of wear caused by kinetic friction between sliding surfaces.
Babbitt metal can be made from differing amounts of tin (Sn), lead (Pb), and copper (Cu). Babbitt metal is soft and easily manipulable, but is also easily damaged. You may think it makes babbitt metal unsuitable for a bearing surface, but the structure consists of small, hard crystals dispersed among the soft metal.
Over time, as the bearing wears, the soft metal gradually wears away, leaving space for lubrication between the hard parts.
Ball Bearing
What is a ball bearing?
The most common type of bearing is the ball bearing. Found in applications ranging from connecting skateboard trucks and the wheels to aerospace applications on commercial, private, and military aircraft, including pulleys, gearboxes, and jet engine shafts.
The purpose of the ball bearing is to reduce the rotational friction to support radial and axial loads. The structure contains two races, one stationary and one moving. Between the two races are the balls.
Unlike other rolling bearings, ball bearings tend to have a lower load capacity due to the minimal contact between the balls and races. However, this results in a much lower coefficient of friction.
Roller Bearing
What is a roller bearing?
Roller bearings are split up into six categories. Unlike ball bearings, roller bearings have a higher load capacity due to the maximized contact between the rollers and the races.
Cylindrical Roller Bearing
The most common type of roller bearing is the cylindrical roller bearing. They use cylinders between the two races which have a slightly greater length than diameter. They experience a higher coefficient of friction when loads are perpendicular to the primary supported direction. Roller bearings actually date back to 40 BCE.
Spherical Roller Bearing
Containing rollers thicker in the middle and thinner at the edges, spherical roller bearings can take on both static and dynamic misalignment. Due to the geometry of the rollers, they are difficult to produce, making them expensive. Due to the amount of sliding between rings and rollers, spherical roller bearings have a higher coefficient of friction.
Gear Bearing
Similar to the gears in a clock or watch, gear bearings consist of gearwheels contained between two races containing equal pitch diameters. Uses include rotary suspension, watches, and kinematically simplified planetary gear. Manufacturing difficulty makes gear bearings an expensive alternative.
Tapered Roller Bearing
Using conical rollers running between conically bored races, tapered roller bearings are designed to handle large radial and thrust loads. Most roller bearings can handle radial or axial loads, so the versatility of the tapered roller bearing is an attractive attribute. Slightly more expensive to manufacture than cylindrical roller bearings, tapered roller bearings are found in car hubs.
Needle Roller Bearing
Using very thin cylindrical rollers, the needle roller bearing is used in automobile components like, rocker arm pivots, pumps, compressors, and transmissions. Technically a needle roller bearing is defined as a roller bearing where the length of the roller is at least four times the diameter.
Thrust Bearing
What is a thrust bearing?
Thrust bearings can either be ball or roller bearings. Ball thrust bearings are designed to handle exclusively thrust loads in low speed, low weight applications. For example, bar stools use ball thrust bearings to swivel. Roller thrust bearings, similarly to ball thrust bearings are designed to handle thrust loads. The difference is in the amount of weight the bearing can handle. Roller thrust bearings can handle a significantly larger amount of thrust load. They are found in car transmissions to support helical gears.
Journal Bearing
What is a journal bearing?
Also known as plain bearings, journal bearings consist of a shaft or “journal” rotating freely in a supporting metal sleeve or shell. What’s unique is there are no rolling elements in a journal bearing. Most times, the shaft is filled with some sort of lubricant – most commonly oil.
Generally the least expensive type of bearing, they are compact and have a high load-carrying capacity. It’s a common practice to apply force to the bearing during installation to achieve a slight elliptical shape.
Journal bearings can also be a type of babbitt bearing. Another version of the journal bearing is the dry journal bearing consisting of a shaft rotating in a dry sleeve. Dry journal bearings are restricted to low-load and low surface speed applications.
-2017 China(Guangzhou) Int’l Bearing and Equipment Exhibition
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