A pillow block bearing (or plummer block) is a pedestal used to provide support for a rotating shaft with the help of compatible bearings and various accessories. The assembly consists of a mounting block which houses a bearing.[1] The block is mounted to a foundation and a shaft is inserted allowing the inner part of the bearing / shaft to rotate.[1] The inside of the bearing is typically 0.025 millimetres (0.001 in) larger diameter than the shaft to ensure a tight fit.[2] Set screws, locking collars, or set collars are commonly used to secure the shaft.[2] Housing material for a pillow block is typically made of cast iron[1] or cast steel.
