TIMKEN METALS PRODUCT CATALOG 18 TIMKEN

METALS PRODUCT CATALOG

The Timken roller bearing's most important dimensions are: The inside diameter of the inner ring, (or cone for tapered roller bearings) is called the bore (d). This diameter must be correct in order to fit the bearing onto the shaft. The outside diameter of the outer ring, (or cup for tapered roller bearings), is known as the outside diameter (O.D. [D]). This diameter must be correct in order to fit the bearing into the housing. The other basic dimension is the bearing width (B). There are three dimensions to consider in tapered roller bearings - cone width (marked B), cup width (marked C) and overall width (marked T).

BEARING TOLERANCES

Timken roller bearings are manufactured to a number of specifications, with each having classes that define tolerances on dimensions such as bore, O.D., width and runout. In addition, bearings are produced in both inch and metric systems with the boundary dimension tolerances being different for these two systems. The major difference between the two systems is that inch bearings have historically been manufactured to positive bore and O.D. tolerances, whereas metric bearings have been manufactured to negative tolerances. Table 1 summarizes the different specifications and classes for tapered roller, cylindrical roller and spherical roller bearings. Boundary dimension tolerances are listed in the following tables. These tolerances are provided for bearings used in metals applications in conjunction with the bearing fitting practices offered in later sections.

EXPLANATION OF TIMKEN BEARING SYMBOLS

TABLE 1. BEARING SPECIFICATIONS AND CLASSES

System Specification Bearing Type Standard Bearing Class Precision Bearing Class Metric Timken Tapered Roller Bearings K N C ISO/DIN All Bearing Types P0 P6 P5 ABMA Cylindrical, Needle Roller Bearings, Spherical Roller Bearings, ADAPT RBEC 1 RBEC 3 RBEC 5 Ball Bearings ABEC 1 ABEC 3 ABEC 5 Tapered Roller Bearings K N C Inch Timken ABMA Tapered Roller Bearings 4 2 3

Fig. 23. Cylindrical roller bearing. Fig. 22. Spherical roller bearing.

NOMENCLATURE

Dimension deviation:

dmp

: Single plane mean bore diameter deviation

Dmp

: Single plane mean outside diameter deviation

Bs

: Inner ring width deviation, i.e. width tolerance

Cs

: Outer ring width deviation, i.e. width tolerance Rotation tolerance: K

ia

: Inner ring radial runout K

ea

: Outer ring radial runout The term deviation is defined as the difference between a single ring dimension and the nominal dimension, therefore being the tolerance range for the listed parameter.

BEARING CLEARANCES

Radialinternal clearance(RIC)is the radial play withinaspherical, cylindrical, needle or ADAPT

TM

bearing. Bench end play (BEP) is the axial internal clearance in a tapered roller bearing before the bearing is to be mounted. For more information, see page 86 of the Timken Engineering Manual - Metals Industry Edition (order no. 10668) or contact your Timken engineer.

Fig. 24. Taper roller bearing (Type TDIT).