pillowblocks

Pillow blocks, also known as pillow block bearings or plummer blocks, are housing assemblies that support a rotating shaft by enclosing a mounted bearing. The assembly consists of a rigid block with a base for mounting to a foundation or frame, a removable cover, and an insert bearing housed inside. The bearing insert—often a ball or roller bearing, or a sleeve bearing in older designs—is secured in place with set screws or a locking collar and is lubricated through a grease fitting or an oil seal.

Construction and variants

Most pillow blocks use a two-bolt base pattern, which provides a compact, easy-to-mount solution. Variants include flange-style or extended units, as well as blocks designed for different mounting arrangements or environmental conditions. The housing protects the bearing from dust and debris while providing a stable alignment support for the shaft. Bearings can be replaceable inserts, enabling easier maintenance and service.

Materials and standards

Pillow blocks are produced in materials such as gray cast iron, ductile iron, steel, or high-strength plastics for light-duty applications. They accommodate a range of shaft bore sizes and are manufactured to recognized bearing standards, allowing compatibility with standard insert bearings from major manufacturers. Selection often follows standard dimension series and bore sizes to match the corresponding shaft components.

Applications and maintenance

Pillow blocks are widely used in conveyors, fans, pumps, woodworking and metalworking machinery, agricultural equipment, and other systems requiring stable shaft support. Proper installation involves ensuring correct shaft alignment, securing the base bolts, and establishing appropriate lubrication and seals. Regular maintenance includes lubricant replenishment, seal inspection, and periodic checks for wear or misalignment to extend bearing life.