Abstract: An improved live roller circle for rotatably supporting the upper frame or body of a large excavator on its lower frame or base is provided. It comprises upper and lower annular rails respectively mounted on the upper and lower frames of the machine. A plurality of tapered rollers, arranged in a circle, roll between and in contact with the rails. The rollers are nominally spaced apart by a circular cage to which the rollers are sufficiently loosely connected to allow them to self-align with respect to the rails irrespective of irregularities in the shape of alignment of the cage. A third annular rail extending around the outer circumference of the circle of rollers is also preferably provided.

Abstract: In a machine having a lower frame, an upper frame having at least one upright wall section, rotatably mounted on the lower frame, and a ring gear mounted on the lower frame, an assembly for swinging the upper frame relative to the lower frame comprising a drive unit mountable on the upright wall section, having a pinion drivingly engageable with the ring gear, means for adjusting the lateral displacement of the drive unit relative to the upper frame, correspondingly adjusting the lateral displacement between the meshing teeth of the pinion and the ring gear, means for adjusting the vertical displacement of the drive unit relative to the upper frame, correspondingly adjusting the vertical displacement of the meshing teeth, providing proper alignment of the meshing teeth and full bearing contact therebetween, and means for rigidly securing the drive unit to the upper frame upon effecting proper adjustment of the displacements between the drive unit and the upper frame.