tailieunhanh - Machinery Components Maintenance And Repair Episode 2 Part 6

Tham khảo tài liệu 'machinery components maintenance and repair episode 2 part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 440 Machinery Component Maintenance and Repair Figure 7-70. Start bearings into housing seat squarely to avoid damage to either bearings or housing. A push fit should be used. This causes noisy operation excessive fretting and pounding out of the housing seat and occasionally excessive spinning in the housing. Testing of Finished Spindle When the spindle has been completely assembled a final check of the eccentricity should be made as follows. Place an indicator point against the center of the shaft extension on the work end of the spindle and rotate the spindle by hand Figure 7-71 . Where possible the opposite end of the spindle also should be checked. Sometimes it is possible to detect roughness or vibration in the spindle when turning the shaft by hand. Roughness may be felt as a hitch or click. Do not attempt to run the spindle if these conditions are major. Dismantle it and find the cause of the roughness. The cause may be the application of excessively dirty lubricant or dirt that has worked its way into the bearing during assembly. Under conditions of slow rotation necessary cage looseness also may create some binding which disappears when running to speed and under load. Vibration is usually detected when the spindle reaches its normal operating speed. Causes of vibration include excessive runout of the pulley a loose cap on the spindle assembly bearings damaged in assembly or possibly loose bearing spacers. In any case when vibration is detected spindle run-in should be discontinued to investigate the cause. Ball Bearing Maintenance and Replacement 441 Figure 7-71. Check eccentricity of assembled bearing with indicator gage on shaft extension. During run-in a close check should be kept on the temperature attained especially in the first part of the run. This is particularly true for spindles which are grease-packed. If the heat becomes excessive over 140 to 150 F 60 to 66 C it is usually advisable to stop the spindle and permit it to cool off. This type of