Technical>Tapered roller bearing
Tapered roller bearing

● Tapered roller bearing components

Tapered roller bearings are designed so that the center lines of the raceways and rollers all converge at a single point as shown in the right diagram. Due to this design feature, rollers move along the center of the raceway surfaces.

Aside from any cautionary notes that may appear, the single row tapered roller bearings have sub-units standardized for both metric and inch systems (including J series).

● Dimension series for metric tapered roller bearings
In the ISO general plan for single row metric tapered roller bearings, the boundary dimensions are grouped for certain ranges of the contact angle, known as the angle series (angle series 2, 3, 4, 5, 6 and 7 in order of increasing angle). Based on the relationship between the outside and bore diameters, and between the total bearing width and the cross-sectional height, diameter and width series have also been established. Here, a dimension series is obtained by combining the angle series with a diameter and a width series. These dimension series consist of one figure for the angle series and two letters, where the first letter identifies the diameter series and the second the width series.

Metric tapered roller bearings Dimension series
Diameter series (outer diameter dimensions) Width series (width dimensions)
number 9, 0, 1, 2, 3
0, 1, 2, 3
dimensions small large
small large

● Dimensions for inch tapered roller bearings

Experience has shown that the requirements of the vast majority of bearing applications can be met using bearings with these standardized dimensions. However, inch sized bearings are still popular nowadays. A large group of bearings in inch sizes are inch tapered roller bearings. The dimensions of these bearings conform to AFBMA Standard 19-1974 (ANSI B3.19-1975). ANSI/ABIVlA Standard 19.2-1994 has subsequently replaced this standard, but this later standard no longer includes dimensions.

● Design of bearing arrangements
When designing bearing arrangements incorporating single row tapered roller bearings, it is necessary to consider the special characteristics of these bearings. Because of their internal design, they cannot be used singly and a second bearing is required; alternatively a paired set may be used. When the arrangement comprises two single row bearings they must be adjusted against each other as described under “Internal clearance and preload”.

A correctly dimensioned operational clearance or preload is vital to the correct performance of single row tapered roller bearings and also to the operational reliability of the arrangement. If the operational clearance is too large, the full load carrying capacity of the bearing will not be exploited. If the preload is too great, then frictional losses will increase, as will operating temperature. In both cases the bearing service life could be substantially reduced.

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