ENGINEERING

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MOUNTING DESIGNS

BEARING ENDPLAY
Correct bearing mounting and fitting practices are key components of proper bearing setting. Setting is the amount of clearance or interference within a mounted bearing. Bearing internal clearance is affected by the tightness of the fi t to the inner and outer races. Proper bearing setting is crucial to bearing life and performance. Although clearance is required for most mounted bearings, application dependent factors include load, speed, bearing position, installation method, materials of construction, runout accuracy, thermal considerations, hoop stress, and shaft and housing design. This section provides tables and discussion to aid in selection of the proper bearing mounting and fi tting procedures to optimize performance in general applications. For special applications, please consult your Timken representative. In certain applications such as vane pumps, rubber mill rotor shafts or where it is necessary to take up axial expansion within the bearing, knowledge of the bearing endplay relationship to mounted radial internal clearance may be required. Table 10 shows the ratio of approximate endplay to radial internal clearance in spherical roller bearings.Example: 22320CJW33C3 bearing has a radial internal clearance of .002 after installation. The total endplay would be approximately .0086 in. (± .0043 from center). Series Endplay RIC RADIAL INTERNAL CLEARANCE (RIC)
39 8.7 30 7.0 22 5.5 31 5.0 40 4.8 32 4.4 23 4.3 41 4.2 33 3.9 Timken bearing RIC allows a tight fi t, with suffi cient internal clearance after installation for normal operating conditions. Table 11 lists the standard RIC ranges for Timken spherical roller bearings with cylindrical and tapered bores. Spherical roller bearings with tapered bore (K) require a slightly greater interference fi t on the shaft than a cylindrical bore bearing. The effect of this greater interference fi t is a reduction of RIC. For tapered bore bearings, it is critical to select the RIC that allows for this reduction.Several factors infl uence RIC reduction. Inner rings pressed into solid steel shafts expand approximately 80 percent of the interference fi t. Outer rings pressed into steel or cast iron housings reduce RIC by about 60 percent of the interference fi t. For RIC reduction on hollow shafts or non-steel materials consult your local Timken representative.Timken bearings are supplied with NORMAL RIC, unless otherwise specifi ed. The desired RIC code must be added to the bearing number, FOLLOWING ALL OTHER SUFFIXES.Min./Max. values for each RIC are shown in the two adjacent columns directly beneath the selected RIC. Each single column represents a boundary between adjacent RICs. For example, the minimum values shown for C5 are also the maximum values for C4; minimum values for C4 are also the maximum values for C3, etc. Table 10. Ratio of approximate endplay-to-RIC for Timken spherical roller bearings. 50
SPHERICAL ROLLER BEARING CATALOG 179761_003-19050 7/19/079:17:51PM