Bucket wheel excavators and stacker reclaimers use large diameter (over 5,000 mm – 196 in) Ball Roller Combination Slewing Rings as main bearings.
Cross section of a typical main Slewing Ring. This unit is a combination type with external toothing and a diameter of 4,800 mm (189 in).
In this combination type Slewing Ring, heavy axial loading is carried by the roller raceway. The ball raceway provides support for light radial loads..