Bearing designations

Metric bearings

The series designations of metric tapered roller bearings with standardized dimensions according to ISO follow one of the following principles:
  • The series designations established in ISO 355:1977 comprising three symbols, a figure representing the contact angle and two letters for the diameter and width series followed by a three figure bore diameter identification (d in mm). The SKF designations are prefixed by the letter T, e.g. T2ED 045
  • Designations established prior to 1977 based on the system shown in fig 1, e.g. 32206.

Metric bearings with a J in the prefix follow the ABMA designation system, which is similar to the system used for inch bearings, see ANSI/ABMA Standard 19.2-1994.

Inch bearings

Inch tapered roller bearings are designated according to the ANSI/ABMA standard.
Metric bearings that belong to the same series maintain the same relative cross section regardless of their size. This is not the case with inch bearings. All inch bearings within a series use the same cage and roller assembly but the inner and outer rings can have different sizes and designs.
Any cone (the inner ring with cage and roller assembly) can be assembled with any cup (the outer ring) belonging to the same bearing series. For this reason the cone and cup have individual designations and can be supplied separately or as complete bearings (fig 2). The designations of the cones and cups as well as the series consist of a three to six-figure number which may be prefixed by one of the following letters or combination of letters: EL, LL, L, LM, M, HM, H, HH and EH. The prefixes characterize a bearing series from extra light to extra heavy. The basic principles of this system are described in ANSI/ABMA Standard 19.2-1994.
The complete bearing designation consists of the cone designation followed by that of the cup, the two designations being separated by an oblique stroke (table).
To shorten the complete bearing designations, abbreviations are used.