A pillow block bearing (plummer block) is a mounted bearing used to provide support for a rotating shaft with the mounting surface on a parallel line with the axis of the shaft.
The bearing housing mounts to a surface parallel to the shaft axis. Selection of the appropriate bearings can be accomplished based on the shaft size and the radial and thrust load requirements. Pillow block bearings are designed to support a shaft: the mounting surface is on a parallel line with the axis of the shaft. Elongated bolt holes in the base or feet of the unit allow for some adjustment and easy mounting of the pillow block bearing.
Certain dimensions and measurements of pillow block bearings are critical to selecting the right pillow block—whether original to the equipment or as a replacement. The shaft diameter is matched with the appropriate corresponding bore dimensions of the bearing unit. If a properly sized unit matching the shaft is selected, the bearing will easily slide onto the shaft and into position, ready to be secured by the locking device. Shaft height also known as backing height is determined by measuring the distance from the base (or bottom) of the pillow block to the center of the inner ring or shaft. Lastly, the distance between the bolt hole centers is taken from the center of one elongated bolt hole to the center of the housing’s other bolt hole.
Housing material for a pillow block bearing is typically made of cast iron or pressed steel. Pillow block bearings are extensively used in conveyor systems such as tube chain conveyors. Most pillow block bearings are self-lubricating.