Patent ID: 7597050
Filing Date: 2009-10-06
Classification: B66C

Abstract:
1. A crane return system for returning a crane component to a home position when there is a loss of power, a crane including a bridge adapted to travel along at least one rail and including a plurality of main wheels to travel along the rail, the crane return system comprising: a plurality of auxiliary drive wheels supported by the bridge, the auxiliary drive wheels movable relative to the bridge between a first position, in which the auxiliary drive wheels are each recessed from the rail and the main wheels are each in contact with the rail, and a second position, in which the auxiliary drive wheels are each in contact with the rail and the main wheels are each recessed from the rail, wherein when power is supplied to the crane the auxiliary drive wheels are in the first position; a hydraulic fluid pressure vessel for storing hydraulic fluid, wherein a substantially fixed mass of hydraulic fluid is contained within the crane return system; a hydraulic cylinder interconnected with the auxiliary drive wheels and selectively fluidly communicating with the hydraulic fluid pressure vessel, wherein when power is lost to the crane, hydraulic fluid is supplied to the hydraulic cylinder to extend the hydraulic cylinder and thereby move each the auxiliary drive wheels from the first position to the second position; and a drive motor interconnected with the auxiliary drive wheels and selectively fluidly communicating with the hydraulic fluid pressure vessel, wherein when the auxiliary drive wheels are in the second position, hydraulic fluid is diverted from the hydraulic cylinder and supplied to the drive motor to rotate the auxiliary drive wheels and move the bridge toward a home position.