Pillow Block Bearings

Pillow block bearings are mounted bearings that are used to provide load support for a rotating shaft’s axis. Their mounting surface is on a line parallel to the axis of the shaft. Elongated bolt holes in the base or feet of pillow block bearings permit adjustment and easy mounting. Product categories include plain bearings, ball bearings, cylindrical-roller bearings, needle-roller bearings, tapered-rolling bearings, hydrodynamic bearings, and more. With pillow block bearings, product selection is based on shaft size, radial and thrust load requirements, and dimensions and measurements.

Shaft diameter, shaft height, and the distance between bolt holes are the main dimensions for pillow block bearings. Shaft diameter must be matched with the appropriate bore dimensions of the bearing unit. Properly-sized pillow block bearings easily slide onto the shaft and into position, ready to be secured by the locking device. Shaft height or backing height is determined by measuring the distance from the base of a pillow block bearing to the center of the shaft. The distance between bolt-hole centers is taken from the center of one elongated bolt-hole to the center of the housing’s other bolt-hole.

Plain bearings and ball bearings are types of pillow block bearings. Plain bearings are used to constrain, guide, or reduce friction in rotary or linear applications. Plain pillow block bearings use a sliding action and must be lubricated properly to reduce wear and friction. Plain bearings are either impregnated with oil or are self-lubricating. Ball bearings are used to provide smooth, low-friction motions in rotary applications. Ball pillow block bearings feature an inner and outer ring and balls. They may be equipped with a cage or ball separator.

There are several roller options for pillow block bearings, including cylindrical and needle. Cylindrical-roller bearings are pillow block bearings with high radial capacities and moderate thrust loads. They can be crowned or end-relieved for reduced-stress concentrations. Cylindrical-roller pillow block bearings produce low friction and allows for high-speed. Needle-roller bearings contain a needle roller. They are designed for radial load applications where a low profile is desired. 

Pillow block bearings can have spherical-roller or tapered-roller options. Spherical-roller bearings are self-aligning, double-row, combination radial and thrust bearings. Typically, the rolling element in these pillow block bearings is crowned or spherical. Spherical-roller pillow block bearings are superior when dealing with high loads and loads that require tolerance to shock; however, they have limited speed capabilities. Tapered-roller bearings contain an inner ring (cone), an outer ring (cup), a cage, and rollers. They have high radial and axial load capacities when used at low to intermediate speed levels. The thrust level of tapered-roller pillow block bearings is about 60% of the radial capacity. 

Hydrodynamic pillow block bearings are available. Hydrodynamic bearings rely on a film of oil that develops clearance while the bearing is rotating. These types of pillow block bearings maintain high stiffness, load capacity, and long bearing life. Other types of pillow block bearings are also available.

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Part Numbers for Pillow Block Bearings