The slewing bearing rocking test should be done periodically for the bearing wear tracking and early failure detection.The measurement could be done from the inside and outside of pedestal. Follow the maker's recommendations and conduct the test at the same check points as during the initial test during commissioning in order all subsequent measurements have the same reference 0.
The measurement should be done as follows:
Two checkpoints should be chosen on the pedestal at the circumference close to the revolving side shell of the crane (see the drawing above) normally at the FWD and AFT of pedestal. Some makers recommend to carry out measurements at four points: FWD, AFT, PORT and STBD of pedestal. Measurement points normally marked at the pedestal.
Measurement should be done by depth meter at four directions of boom: FWD, AFT, PORT and STBD. At each boom direction two or four readings must be taken (see item 1 above), check maker's recommendations for details. Record obtained figures on the log sheet. Result of periodic measurement record should be compared with the max. allowable deviation provided by the manufacturer.
Some rocking test procedures require to use a dial gauge instead of depth meter.In this case dial gauge set to 0 after installing at the measurement point and readings taken at four boom positions: FWD, AFT, PORT and STBD. Same procedure repeated for all measurement points as it was done during initial the rocking test.