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12916 Parts & Specifications Manual #99905833
Turntable Bearing Inspection
Turntable bearings may experience wear. One of the following conditions may indicate turntable
bearing wear.
1
Metal particles present in the bearing lubricant.
2
Increased drive power required to rotate the crane.
3
Noise emitting from the bearing during rotation.
4
Rough rotation.
5
Uneven or excessive wear between the pinion gear and turntable gear.
If none of the above conditions exists, the bearing is functioning properly and need not be
replaced. But, if one or more of the above conditions exists, inspection may be required. Limits
are measured in “TILT” which is dependent on the internal clearances of the bearing. TILT is the
most practical determination of a bearings internal clearance once mounted on a crane.
Periodic readings indicating a steady increase in TILT may be an indicator of bearing wear.
Note that a bearing found to have no raceway cracks or other structural irregularities should be
reassembled and returned to service.
TEST PROCEDURE
1. Place crane in vertical position.
2. Set a dial indicator at 0 on the pinion cover plate at back side of mast.
3. Lower crane to the horizontal position.
4. Check and record the dial indicator change. It should not exceed the tilt measurement
noted in the chart below.
5. Return the crane to the vertical position. The dial indicator should return to 0.
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