Tapered Roller Bearings Information
Tapered roller bearings consist of an inner ring (cone), an outer ring (cup), a cage and rollers which are profiled to distribute the load evenly. They have high radial and axial (thrust) load capacities at low to intermediate speeds. Tapered roller bearings are available in single-row, two-row and four-row designs. With single-row bearings, the thrust load capacity is about 60% of the radial capacity. Double-row bearings have a greater radial load capacity and can handle thrust loads from both directions. The rollers can be configured so that the contact lines to the races converge or diverge towards the axis of rotation. Diverging double-row bearings increase the rigidity of the shaft mounting, but converging bearings do not. Other configurations for double-row bearings feature a single outer ring and two inner rings, or two outer rings and a single inner ring. Four-row tapered roller bearings consist of four rows of alternating converging and diverging rollers.
Most tapered roller bearings are made of alloy steels or low-carbon steels. 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 cylindrical 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
Bore size and outside diameter (OD) are important specifications to consider when selecting tapered 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 tapered 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.
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Ball Screw Support Bearings
Ball screw support bearings are designed for use in ball or lead screw applications.
Ceramic hybrid bearings, the most common type of ceramic bearing, are constructed of steel inner and outer rings with ceramic (typically Si3N4) balls in place of steel. Common types of ceramic bearings are angular contact and conrad.
Cylindrical Roller Bearings
Cylindrical roller bearings have high radial-load capacity and moderate thrust loads. They contain rollers which are cylindrically-shaped, but crowned or end-relieved to reduce stress concentrations.
Slewing Rings and Turntable Bearings
Slewing rings and turntable bearings can accommodate axial, radial and moment loads. They are not mounted in a housing or on a shaft, but are instead mounted directly to a seating surface via mounting holes.
Spherical Roller Bearings
Spherical roller bearings are self-aligning, double row, combination radial and thrust bearings. They use a spherical or crowned roller as the rolling element.
Super Precision and Spindle Bearings
Super precision and spindle bearings are high-precision bearings that are designed for use in machine-tool spindles and other precision applications. Most super precision bearings and spindle bearings carry a high quality-rating such as ABEC-7 or ABEC-9, and run coolly and smoothly at high speeds.
Thrust bearings are designed for pure thrust loads, and can handle little or no radial load. The rolling element in a thrust bearing can be a ball, needle or roller.