How are dimensions of friction bearings typically expressed?

Friction bearings, commonly referred to as plain bearings, are often discussed in terms of their nominal sizes, particularly the inner diameter, outer diameter, and length. The nominal sizes represent the primary dimensions that are critical for ensuring the proper fit and function of the bearing within its housing or against the shaft.

When specifying a friction bearing, the inner diameter is especially important because it must closely match the shaft size to ensure efficient rotation and minimize wear. In addition to the inner diameter, the outer diameter and length are also considered to fully characterize the bearing, but the nominal size, particularly the inner diameter, becomes the focal point since it directly impacts how the bearing interfaces with the shaft.

While tolerances might play a role in bearing specifications—indicating the acceptable range for dimensions to ensure proper fit—the choice of expressing dimensions with a focus on nominal sizes is typically more standard in industry discussions related to friction bearings. This approach allows for clear communication about the key measurements necessary for installation and operation.