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<strong>Timken</strong> ® SAF SPLIT-BLOCK HOUSED UNITS<br />
Engineering • Bearing Types and Cages / Metric System Tolerances<br />
RADIAL SPHERICAL ROLLER BEARING TYPES and Cages<br />
The principle styles of radial spherical roller bearings that <strong>Timken</strong><br />
offers are:<br />
• ≤280 mm bore: EJ, EM and EMB<br />
• >280 mm bore: YM and YMB<br />
Above suffixes correspond to different types of designs depending<br />
on a bearing size and geometry. Main differences are the cage<br />
type used in the assembly. Spherical roller bearings with an EJ<br />
cage suffix are fitted with a stamped-steel cage. YM/EM/YMB<br />
suffixes are used with brass cage designs.<br />
The newly redesigned <strong>Timken</strong> ® EJ, EM and EMB bearings offer<br />
higher load ratings, increased thermal speed ratings and reduced<br />
operating temperatures compared to the previous offering.<br />
In addition to these improvements, cage designs vary between<br />
the different styles as noted below.<br />
Style<br />
EJ<br />
EM/YM<br />
EMB/YMB<br />
Cage Design<br />
land-riding steel cage; one per row<br />
Roller-riding one-piece brass cage<br />
Land-riding one-piece brass cage<br />
Most <strong>Timken</strong> ® spherical roller bearings are available with a<br />
cylindrical bore as well as a tapered bore. Tapered bore bearing<br />
part numbers are designated with a K suffix.<br />
Metric System Tolerances<br />
Spherical roller bearings are manufactured to a number of<br />
specifications, with each having classes that define tolerances<br />
on dimensions such as bore, O.D., width and runout. Metric<br />
bearings have been manufactured to corresponding standard<br />
negative tolerances.<br />
Boundary dimension tolerances for spherical roller bearing<br />
usage are listed in the following tables. These tolerances are<br />
provided for use in selecting bearings for general applications,<br />
in conjunction with the bearing mounting and fitting practices<br />
offered in later sections.<br />
The following table summarizes the different specifications and<br />
classes for spherical roller bearings and other available <strong>Timken</strong><br />
bearing lines. For the purposes of this catalog, ISO specifications<br />
are shown for spherical roller bearings.<br />
Table D-1. Bearing Specifications and classes<br />
System Specification Bearing Type Standard Bearing Class Precision Bearing Class<br />
Metric ISO/DIN All Bearing Types P0 P6 P5 P4 P2 –-<br />
Imperial ABMA Spherical RBEC 1 RBEC 3 RBEC 5 RBEC 7 RBEC 9 –-<br />
D-4 TIMKEN ® HOUSED UNIT CATALOG