In brief
A tapered roller bearing is a rolling bearing with conical rollers that can carry high radial loads and axial loads in one direction at the same time.
Contents
What is Tapered roller bearing?
In a tapered roller bearing, the raceways and rollers are conical, and their imaginary extensions meet at a point on the bearing axis. The bearing can therefore carry combined loads: high radial forces together with axial forces in one direction. The larger the contact angle, the higher the axial load capacity. The bearing is separable; the inner ring with rollers and cage is called the cone, and the outer ring the cup.
Because a single tapered roller bearing only carries axial load in one direction, two bearings are usually adjusted against each other, in a back-to-back (O) or face-to-face (X) arrangement. Clearance or preload is only created during mounting and is set using nuts, spacers or shims. Besides single-row designs, there are matched, double-row and four-row versions. Metric and inch series exist and are not interchangeable with each other.
Tapered roller bearings are found in gearboxes, rope sheaves, rolling mills, cranes and pumps. Common sources of failure are incorrectly set clearance, lack of lubricant and mixing cones and cups from different sources.
In practice: maintenance and procurement
In an enquiry, the cone and cup should each be stated with their full designation, especially for inch bearings, which have separate part numbers. After replacement, the specified clearance or preload must be set according to the manufacturer’s instructions.
Synonyms and abbreviations: TRB · taper roller bearing · tapered roller radial bearing · cone and cup
Frequently asked questions
What is the difference between back-to-back (O) and face-to-face (X) arrangement?
In the back-to-back (O) arrangement, the load lines of the two bearings diverge outwards, the support base is wide and the bearing arrangement is rigid against tilting. In the face-to-face (X) arrangement, the load lines converge inwards and the base is narrower, but the arrangement is less sensitive to misalignment and easier to adjust. Which arrangement is fitted is determined by the design and should be retained when replacing.
Can cones and cups from different manufacturers be combined?
Dimensionally, standardised parts often fit together. Nevertheless, many manufacturers recommend using cone and cup as a set from one source, because raceway geometry and tolerances are matched to each other. Mixing is ruled out for matched or preloaded sets. If in doubt, the complete set should be replaced.
What information is needed to replace a tapered roller bearing?
The designations of cone and cup or the set designation are needed, along with whether it is a metric or inch version and, for matched bearings, the type of pairing. If designations are missing, bore, outside diameter, total width, width of cone and cup and a photo of the markings help.
Why does a tapered roller bearing have to be adjusted?
Because the bearing clearance only results from the axial position of the two bearings relative to each other. Too much clearance leads to knocking and uneven load distribution, too much preload to heating and early failure. The machine manufacturer usually specifies a setting dimension, frictional torque or axial displacement to which the bearing is adjusted.