Abstract: Apparatus such as a mining shovel or the like, the apparatus comprising a carbody supported for movement over the ground, the carbody including a cylindrical bore centered on a vertical axis. A cylindrical center gudgeon is housed in the cylindrical bore, the center gudgeon including a generally cylindrical outer surface having therein a groove defining a generally horizontal plane, and a flat defined by a vertical, planar surface forming a chord of the outer surface. A bottom retainer includes a plurality of ring segments housed in the groove, and a key having a vertical, planar key inner surface engaging the center gudgeon flat and facing the ends of two of the ring segments. The key is welded to the carbody so that the key is stationary relative to the carbody and prevents rotation of the center gudgeon relative to the carbody.