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TIMKEN cylindrical roller bearing installation, fit, clearance adjustment and installation

by:JNSN     2022-03-16
Mounting: Cylindrical roller bearings can be mounted individually, but will usually be used in conjunction with another cylindrical roller bearing, spherical roller bearing, or tapered roller bearing. Figure 8 shows a coal mill roller using a combination of double row spherical roller bearings and one row cylindrical roller bearings. Cylindrical roller bearings in this application allow the shaft to float relative to the housing. Figure 9 shows a one-stage reducer with herringbone teeth. The input shaft is fitted with a row of tapered roller bearings and a row of cylindrical roller bearings. The output shaft is fitted with two rows of cylindrical roller bearings. Fits: Tables 6 through 18 on pages 22 through 33 give recommendations for cylindrical roller bearing fits. It is mainly based on the following conditions: The bearing is of ordinary precision grade The bearing seat is thicker and made of steel or cast iron The shaft is a solid shaft and made of steel The bearing mating surface is ground and the surface roughness is less than 1.6um Ra Recommended fit symbol Compliant with ISO 286 standard. For dosage recommendations, please contact your Timken representative. Figure 8. Coal Mill Roller Figure 9. Primary Reducer Cylindrical Roller Bearing Installation, Fitting, Clearance Adjustment and Installation Warning Proper maintenance and operation are critical. Always follow installation instructions and maintain proper lubrication. It is strictly forbidden to use compressed air to rotate the bearing, which may cause the bearing parts to eject at high speed. Failure to observe the following warnings could result in serious personal injury or death. Thermal Gradient: The thermal gradient within a bearing is a function of bearing speed. The thermal gradient also rises during acceleration, the heat increases, and the radial clearance decreases. As a rule of thumb, when the actual speed exceeds 70% of the rated speed, the radial clearance should be increased. Consult your Timken representative to select the correct diameter. internal clearance. The radial internal clearance tolerances are listed in Table 5. Standard or non-standard radial internal clearances are specified when ordering cylindrical roller bearings. Standard radial internal clearance is C2, C0 (standard), C3, C4 or C5 according to ISO5753. C2 represents the minimum clearance and C5 the maximum clearance. Non-standard clearances are available on specific request. The amount of radial clearance depends on the running accuracy, bearing speed and fit required by the application. Standard clearance or C3 clearance is chosen for most applications. Larger clearances generally reduce the bearing load area, increase the maximum load on the rollers, and reduce the bearing life expectancy. However, cylindrical roller bearings in the preloaded state may be prematurely scrapped due to excessive heat generation or material fatigue damage. A basic principle is that cylindrical roller bearings should avoid operation with negative clearance. As a general rule, the rotating inner ring should be an interference fit. A loose fit can cause the inner race to slip and run the race and cause wear on the shaft and shoulders. Such wear can lead to loose bearing assembly and damage to the bearing and shaft. In addition, metal abrasive particles from the inner ring running ring may enter the bearing and cause bearing damage or vibration. The fit of the stationary inner ring depends on the load conditions of the application. Use the load conditions and bearing dimensions to select the recommended shaft fit in the table. Likewise, applications where the outer ring rotates should have an interference fit between the outer ring and the housing. The stationary outer ring is usually loose fit for easy installation and removal. Thin-walled housings, light-alloy housings or hollow shafts must have a tighter interference fit than would be required for thick-walled housings, steel/cast iron housings, or solid shafts. A tight fit is also required when the bearing is mounted on a relatively rough or unfinished surface. Clearance adjustment: In order to obtain the proper operating clearance, attention must be paid to the influence of the fit and the thermal gradient effect of the bearing. Fit: The interference fit between the inner ring and the solid steel shaft will reduce the radial clearance in the bearing by approximately 85% of the fit. An interference fit between the outer ring and a steel or cast iron housing will reduce the radial clearance by approximately 60%.
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