TechDoc
Subject:
Rotation Bearings – Inspection of internal clearance
Date:
1/30/2006
No.:
TD10002
Model/Series:
All
Manufacturers of rotation bearings list several symptoms that become apparent when the bearing
has reached its useful life. These include:
•
•
•
•
•
Metal particles in the grease
Increased drive power required
Noise
Rough operation
A steady increase of bearing clearance which accelerates towards the end of the
bearing life
The internal clearance can be measured and is a good means of determining bearing condition.
Listed below is an accepted procedure for determining internal bearing clearance. A dial indicator
with magnetic base is required to perform this procedure.
1. Start with boom in boom rest and outriggers and stabilizers properly set.
2. Attach dial indicator base to top of frame side plate or top plate on the side opposite the
direction the boom is pointing (see Figure 1).
3. Locate dial indicator needle on turret base plate (see Figure 1).
4. Power boom down in boom rest.
5. Reset dial indicator to zero.
6. Raise boom approximately 3” above boom rest.
7. Record deflection indicated on dial.
8. Repeat Steps 4 – 7 three times and average the readings.
9. If the average deflection is greater than 0.090”, the bearing should be replaced.
10. If the average deflection is less than 0.090”, then repeat measurement procedure every 45°
around entire working area of crane. Referring to Figure 2, measure deflection at positions
2, 3, 7 and 8 for 180° rotation and positions 2 – 8 for 360° rotation. Locate dial indicator on
frame directly opposite to the direction the boom is pointing. Also use another crane or
overhead hoist to support end of boom while powering down and resetting dial indicator. An
average deflection greater than 0.090” in any position is an indication that the bearing has
reached its useful life and should be replaced.
Page 1 of 2
Manitex Inc. Š 3000 S. Austin Ave Š Georgetown, TX 78626 Š www.manitex.com Š ph: 512-942-3000
TechDoc: TD10002
NOTE:
Although the above procedure can be used to gauge the condition of the rotation bearing, the
bearing manufacturer reserves the right to make a final inspection, at their facility, to determine if in
fact the bearing is out of tolerance. This is of particular importance when considering the
replacement of a bearing while still within the warranty period. If the bearing is deemed to be within
tolerance by the manufacturer, the owner of the equipment will be responsible for costs associated
with the removal and re-installation of the bearing.
For additional information please contact the Manitex Product Support Department by e-mail
[email protected] or call 512-942-3031.
Page 2 of 2
Manitex Inc. Š 3000 S. Austin Ave Š Georgetown, TX 78626 Š www.manitex.com Š ph: 512-942-3000