Trolley for moving loads on crossed rail system has interlocking drives to prevent retraction of one set of wheels until the other set of orthogonal wheels is deployed

摘要

A trolley for moving heavy loads over a system of crossed rails has two sets of wheels set at right angles to each other and retracting when not required. The wheels are mounted on an interlocked linkage which ensures that a set of wheels cannot be retracted until the other set is fully deployed. The linkage is operated by two sets of manual levers, on opposite sides of the trolley. Each wheel set is mounted on the bottom of a pendant mounted support arm which is linked to a near horizontal control arm coupled to the operating levers. The trolley remains in the same horizontal setting during direction change reducing the drive force required to change direction.