Roller bearings are also known as rolling-element bearing. A roller bearing is a bearing which carries a load by placing round elements between the two pieces. The relative motion of the pieces causes the round elements to roll (tumble) with little sliding. Common roller bearings use cylinders of slightly greater length than diameter. Roller bearings typically have higher radial load capacity than ball bearings, but a low axial capacity and higher friction under axial loads. If the inner and outer races are misaligned, the bearing capacity often drops quickly compared to either a ball bearing or a spherical roller bearing.
The roller buffer is designed to buff the wear surface of the roller prior to rebuilding. Steam or a high-pressure water cleaning system prior to buffing must remove the bulk of field dirt. Its features include variable speed control of the roller buffer shaft and counterbalanced hood assures adequate contact pressure for buffing the roller.