 Previous Page 350.1
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Bearing
Installation
Background Most bearing failures are caused by contamination of the bearings before they are installed. In turn, bearing failure causes other mechanical and electrical failures of motors. Proper bearing installation ensures long bearing service. Proper installation depends upon uncontaminated and properly fitted bearings. This ensures long motor life and avoids later unnecessary repair work. Bearing installation Ensure that the workspace, equipment, and tools are clean and ready for immediate use. Measure bearing housing and journal diameters to ensure that they are within size limits. Use a snap gage to measure shaft bearing journal diameter. Use a bore gage to measure bearing housings. Check the measurements against the original measurements made on the incoming motor and recorded in the motor data sheet (mechanical).
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Carefully check the bearing identification number before removing packaging.
Rinse open-type bearings or bearings used in oil-lubricated systems in clean 2190 TEP oil to remove grease. Heat the oil to 140°F ± 10°F. Agitate the bearing in the oil until all grease is removed. Drain off excess oil. If it is a grease-lubricated bearing cleaned for use with oil, prepare the bearing for heating by putting it in heat-resistant plastic or aluminum foil.
Heat the bearing Preheat a heat-controlled oven to 203°F ±10°F. Heat the bearing in the oven for 30 minutes to 1 hour. Ensure that the bearing is fully expanded. Install the inner bearing cap on the shaft. Reinspect all parts to ensure that they are free of dirt, burrs, and scratches. Using clean, thermo-insulated gloves, remove the bearing from the oven. Remove the plastic cover or unwrap the aluminum foil from the bearing.
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Click on image to
enlarge. Bearing Numbering System |
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| Install the bearing
on the shaft immediately. Hold the inner ring in place against the shaft shoulder until
the bearing has cooled enough to remain on the shaft.
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Click on image to
enlarge. Installation of Heated Bearing
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| Use a locknut
spanner wrench to install the lockwasher and locknut on the bearing. Torque to the value shown in the Bearing Locknut Torques table. To compensate for contraction, retorque to the proper torque locknut value (Recommended Prevailing Torque Values, Locknut Reuse table) when the unit has cooled. For grease-lubricated open and single closure bearings, pack the bearing one-third to one-half full of grease.
Duplex bearing installation
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Click on image to
enlarge. Typical Locknut Spanner Wrench and Table of Dimensions Click on image to enlarge. Torque Wrench Application Methods |
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| Install the inner
bearing using the procedures previously described. Insert a spacer of same size and install the lockwasher and locknut. Use an old bearing with an enlarged bore for a spacer; torque the locknut as required. Retorque when cool. Remove the locknut, lockwasher, and spacer just before installation of the outer bearing. Install the outer bearing, lockwasher, and locknut. Torque as required. Retorque when cool. Checking bearing alignment after installation
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Click on image to
enlarge. Typical Duplex Bearing Installation |
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| Use a dial
indicator to check
bearing alignment. Maximum inner ring runout If all tests are satisfactory, the rotor will be considered ready for installation. Cover bearings with lint-free material to avoid contamination until actual installation occurs. |
Click on image to
enlarge. Setup to Check Inner Ring Runout |
Bearings
packed in grease in accordance with DOD-G-24508 can be installed as received.
| Review Questions If you can correctly answer the questions below, you have learned the key points in this lesson. Choose the correct answer for each question, then look at your score below the questions. Review the lesson if you miss any questions. |