Castor

摘要

A castor comprising a socket member defined by a base portion and a cup portion extending from the base portion, the base portion being adapted to be affixed to the underside of an article, and the cup portion defining a generally dome-shaped cavity therein. A ball is engaged in the cavity in a manner to be freely rotatable in any direction in the cavity. The cup portion has six equally spaced rollers rotatably mounted to the wall of the cavity and supports the ball for rotatable movement within the cavity, the rollers being supported on bearings which in turn are supported on inwardly projecting lugs integral with the cavity walls. The rollers contact the ball at an angle of less than 45 DEG with respect to the horizontal axis of the ball. An annular rim defines an open end of the cavity, through which a portion of the ball outwardly projects, and a circumferential lip is arranged adjacent the annular rim, the lip projecting inwardly towards the surface of the ball, to maintain the ball within the cavity but being resiliently yieldable to permit the ball to be mounted in or removed from the cavity by applying force to the ball.