51 Inch Four-Point Contact 1308x1634x94mm Ball Slewing Ring Bearing - inside Gear51 Inch Four Point Contact 1308x1634x94 mm Ball Slewing Ring Bearing with inside Gear Four Point Contact Ball Slewing Bearing with inside Gear A slewing bearing ring is a rotational rolling element bearing that typically supports a heavy but slow turning or slow oscillating load, often a horizontal platform such as a conventional crane, or the wind facing platform of a horizontal axis windmill. (To 'slew' means to turn without change of place.) Item