Spherical roller bearings feature a large load rating and
self-aligning capability. This type of bearing is suitable for low- or medium
speed applications which involve heavy or impact loading.
Spherical roller bearings are self-aligning, double-row, combination radial and thrust bearings. They use a spherical or crowned roller as the rolling element. The outer ring contains a spherical race which allows for some misalignment of the shaft and housing. Spherical roller bearings are unequalled in their capacity for high loads and tolerance to shock loads, but have limited speed capabilities. They perform consistently, even under conditions of extreme speed, application-specific stress, and marginal lubrication. The cage of a spherical roller bearing provides high dimensional accuracy and functionality. According to some estimates, spherical roller bearings have twice the running life of conventional bearings.
Most spherical roller bearings are made of alloy steels or low-carbon steels. Chrome-plated products are also available. Some applications require the use of case-hardened or thorough-hardened, high-carbon, bearing-quality steel. High-carbon grades of steel do not require carburizing and can be case-hardened by induction heating or thorough-hardened by conventional heating methods. When low-carbon, carburized grades of steel are used, carbon is introduced after the spherical roller bearings are machined to a depth sufficient to produce a hardened case that can sustain bearing loads. The addition of carbon and alloys ensures the proper combination of a hard, fatigue-resistant case and a tough, ductile core.
Bore size and outside diameter (OD) are important specifications to consider when selecting spherical roller bearings. The bore size is the bearing's smallest dimension. The outer diameter includes the bearing housing, but excludes the flange. Other important specifications for spherical roller bearings include overall width, rated speed (oil), static axial load, static radial load, dynamic axial load, and dynamic radial load. Static axial load and static radial load are, respectively, the maximum axial and radial loads that bearings can withstand without permanent deformation. Dynamic axial load and dynamic radial load are, respectively, the calculated axial and radial loads under which a group of identical bearings with stationary outer rings can endure for a rating life of 1 million revolutions of the inner ring.
These bearings are divided into R, RH(R) and RHA types, which differ in internal structure. Each type can be produced with a cylindrical bore or tapered bore. Bearings with a tapered bore can be fit and removed easily using an adapter assembly or withdrawal sleeve. The rate of taper is equivalent among all bearing series.