48 Inch Four-Point Contact 1224x1512x89 mm Ball Slewing Ring Bearing with inside Gear48 Inch Four Point Contact 1224x1512x89 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