Method of machining the upper pad on the swing bearing of a large excavator

In an excavator having a base which supports a revolving frame for rotation about an upright pintle, having an annular swing gear mounted to the base concentric about said pintle, having an annular lower bearing pad mounted to the base and concentric about said pintle, having an annular upper bearing pad mounted to the revolving frame and positioned directly above said lower bearing pad, and having a set of bearings disposed between opposing surfaces on said upper and lower bearing pads in a circle about said pintle, a method of machining the surface of said upper pad, the steps comprising:

• raising said revolving frame to lift said upper pad upward and out of engagement with said set of bearings;
• removing a selected number of said bearings to expose a sector of said lower bearing pad;
• mounting a metal cutting machine over said exposed sector of said lower bearing pad;
• inserting temporary rollers between said swing gear and the bottom surface of said raised revolving frame;
• lowering said revolving frame onto said temporary rollers;
• and
• rotating said revolving frame while operating said metal cutting machine to machine the entire surface of said upper bearing pad.

A method of machining annular shaped lower and upper bearing pads on an excavator to provide uniform spacing therebetween, the steps comprising:

• assembling a base which mounts said lower bearing pad;
• establishing a reference surface on the excavator base which extends around a central swing axis of the excavator and which is perpendicular thereto;
• machining the lower bearing pad parallel to said reference surface by supporting a metal cutting machine on said reference surface and swinging it around said central swing axis;
• assembling a revolving frame which mounts said upper bearing pad directly above said machined lower bearing pad;
• supporting said revolving frame on said reference surface for rotary motion about said central swing axis;
• machining said upper bearing pad with a metal cutting machine mounted to the base beneath said upper bearing pad by rotating the revolving frame.