... the steel balls do contact with 4 points of the circular orbit, so it can undertake the Axial Force, Radial ... life and good sealing performance feature. (6). Ferris wheelUsually use four-point contact ball slewing bearing, diameter 4100mm, thickness 85mm. (7 ... maintain, grease and seal. (12). Engineering machineryUsually use small size four-point contact ball bearings or double-row ball, diameter not ...