Case Study: Replacement of a roller element bearing on the main shaft of a large double drum hoist

Requirements: The bearing inboard of a direct-drive motor on the main shaft of a large hoisting plant experienced premature failure.  A plan was required to remove the large roller element bearing while minimizing downtime on the only production hoist at the mine site. 

A detailed procedure was developed to safely replace the bearing while minimizing interruptions to the operation of the mine site.  The procedure detailed removal of the large 1,000 hp direct drive AC motor stator and rotor as well as lifting the drum assembly to allow removal of the bearing from the housing.

Detailed drawing packages were prepared for fixturing and rigging to lift the motor rotor and hoist drum assembly.  Specialized hydraulic tooling was specified to evenly raise the hoist assembly.  Procedures provided detailed listings of all rigging equipment and specialty tools as well as target values for re-installation of the bearing and other hoist mechanicals. 24-hour on site support was provided during the removal to support heavy lifts and ensure the return of the hoist to safe operating conditions prior to resuming normal operations.

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