bearing

In machine construction, a connector (usually a support) that permits the connected members to rotate or to move in a straight line relative to one another. Often one of the members is fixed, and the bearing acts as a support for the moving member. Most bearings support rotating shafts against either transverse (radial) or thrust (axial) loads. To minimize friction, the contacting surfaces in a bearing may be separated by a film of oil or gas; these are sliding bearings (see oil seal). In ball bearings and roller bearings, the surfaces are separated by balls or rollers.