Crane return

A crane comprising:

• a bridge adapted to travel along a pair of rails, the bridge including a plurality of main wheels and a plurality of auxiliary drive wheels, the auxiliary drive wheels movable relative to the bridge between a first position, in which the auxiliary drive wheels are each recessed from the rails and the main wheels are each in contact with the rail when power is supplied to the crane, and a second position, in which the auxiliary drive wheels are each in contact with the rails and the main wheels are each recessed from the rail when power is off to the crane;
• a hydraulic fluid pressure vessel filled with hydraulic fluid;
• a hydraulic cylinder interconnected with the auxiliary drive wheels and selectively fluidly connected with the hydraulic fluid pressure vessel, wherein when power is lost to the crane, hydraulic fluid is delivered from the hydraulic fluid pressure vessel to the hydraulic cylinder to extend the hydraulic cylinder and thereby move each of 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 connected 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 delivered from the hydraulic fluid pressure vessel to the drive motor to rotate the auxiliary drive wheels and move the bridge toward a home position.

A method for returning a crane component to a home position upon a loss of power to a crane, the crane including a bridge adapted to travel along at least one rail with a plurality of main wheels in contact with the rail and a plurality of auxiliary drive wheels recessed from the rail, the method comprising:

• supplying and storing hydraulic fluid in a hydraulic fluid pressure vessel;
• upon a loss of power to the crane, supplying hydraulic fluid from the hydraulic fluid pressure vessel to a hydraulic cylinder interconnected with the auxiliary drive wheels, the hydraulic cylinder extending to move each of the auxiliary drive wheels into contact with the rail;
• removing the main wheels from contact with the rail when the auxiliary drive wheels are moved into contact with the rail;
• supplying hydraulic fluid from the hydraulic fluid pressure vessel to a drive motor when the auxiliary drive wheels contact the rail to drive the auxiliary drive wheels such that the bridge travels along the rail toward the home position, wherein hydraulic fluid is diverted from the hydraulic cylinder;
• and
• stopping the flow of hydraulic fluid to the drive motor when the bridge reaches the home position to thereby stop the auxiliary drive wheels.