Common
By far, the most common bearing is the plain bearing, a bearing which uses surfaces in rubbing contact, often with a lubricant such as oil or graphite. A plain bearing may or may not be a discrete device. It may be nothing more than the bearing surface of a hole with a shaft passing through it, or of a planar surface that bears another (in these cases, not a discrete device); or it may be a layer of bearing metal either fused to the substrate (semi-discrete) or in the form of a separable sleeve (discrete). With suitable lubrication, plain bearings often give entirely acceptable accuracy, life, and friction at minimal cost. Therefore, they are very widely used.
However, there are many applications where a more suitable bearing can improve efficiency, accuracy, service intervals, reliability, speed of operation, size, weight, and costs of purchasing and operating machinery.
Thus, there are many types of bearings, with varying shape, material, lubrication, principle of operation, and so on.
Read more about this topic: Bearing (mechanical)
Famous quotes containing the word common:
“Thus Pegasus, a nearer way to take,
May boldly deviate from the common track.
From vulgar bounds with brave disorder part,
And snatch a grace beyond the reach of art,
Which without passing through the judgment, gains
The heart, and all its end at once attains.”
—Alexander Pope (1688–1744)
“This is really the common mentality of prisoners: they read with great attention all the articles that deal with illnesses and send away for treatises and “be your own doctor” or “emergency treatments” and end up by discovering that they have at least 300 or 400 illnesses, whose symptoms they are experiencing.”
—Antonio Gramsci (1891–1937)
“Nothing is more repugnant to me than brotherly feelings grounded in the common baseness people see in one another.”
—Milan Kundera (b. 1929)