Transferable guide pulleys for rolling overhead telescopic bridge or gantry crane

Claim 1

A POWER-DRIVEN OVERHEAD TRAVELLING CRANE COMPRISING A ROLLING BRIDGE; A TELECOPING BOOM OF SUSBSTANTIALLY THE SAME LENGTH AS SAID BRIDGE AND SLIDABLY SUPPORTED THEREIN AND RECIPROCALLY SHIFTABLE ENDWISE FROM A RETRACTED POSITION INSIDE OF SAID BRIDGE TO AN OUTWARD EXTENDING POSITION WHEREIN IT PROJECTS AT LEAST IN PART FROM EITHER SIDE END OF SAID BRIDGE; A ROLLING CRAB RIDING ON SAID BOOM AND CONTINUOUSLY MOVABLE ALONG THE FULL LENGTH OF BOTH OF SAID BRIDGE AND BOOM FROM THE FREE EXTREME PROJECTING SIDE END OF SAID BOOM IN ITS OUTWARD EXTENDED POSITION TO THE OPPOSITE REMOTE EXTREME SIDE END OF SAID BRIDGE, THUS BEING INDIFFERENTLY SUPPORTED BY EITHER OF SAID BRIDGE AND BOOM; LOAD CARRYING MEANS WITH A PENDENT BLOCK SUPPORTED FROM SAID CRAB AND ADAPTED FOR VERTICAL MOVEMENT TO AND FROM SAID CRAB; AT LEAST ONE MOTORIZED CRAB HAULAGE WINCH CARRIED BY SAID BRIDGE AND PROVIDED WITH AT LEAST ONE PAIR OF REVERSIBLY COUNTER-ROTATING CABLE WINDING DRUMS; AT LEAST ONE PAIR OF CRAB HAULAGE CABLES WOUND ON SAID DRUMS, RESPECTIVELY, WITH OPPOSITE END PORTIONS EXTENDING THEREFROM OUT TO THE OPPOSTE SIDE ENDS OF SAID CRANE, TO BE REEVED AROUND A PAIR OF HAULAGE END SHEAVES RESPECTIVELY CARRIED ENDWISE BY SAID OPPOSITE SIDE ENDS OF SAID CRANE AND THENCE BACK TOWARD EACH OTHER FOR BEING DEAD-ENDED ON SAID CRAB; AT LEAST ONE MOTORIZED HOISTING WINCH CARRIED BY SAID BRIDGE AND PROVIDED WITH AT LEAST ONE ROPE WINDING REVERSIBLY ROTATING DRUM; AT LEAST ONE LIDTING ROPE FOR RAISING AND LOWERING SAID LOAD CARRYING MEANS, WOUND ON SAID DRUM AND EXTENDING THEREFROM OUT TO ONE SIDE OF SAID BRIDGE WHEREIT IS REEVED ABOUT A HOISTING END SHEAVE CARRIED BY SAID ONE SIDE END OF SAID CRANE THENCE BACK TO SAID CRAB WHERE IT PASSES OVER A FIRST SHEAVE ON THE LATTER, THENCE DOWNWARDS AND ABOUT SAID PENDENT BLOCK, THENCE UPWARDS ABOUT A SECOND SHEAVE ON SAID CRAB, THENCE TO AND ABOUT ANOTHER HOISTING END SHEAVE CARRIED BY THE OTHER SIDE END OF SAID CRANE FOR BEING MADE FAST ON SAID BRIDGE; BOTH OF SAID HAULAGE AND HOISTING END SHEAVES AT EACH SIDE END OF SAID CRANE BEING ROTATABLY MOUNTED ON A COMMON SHEAVE SUPPORTING FRAME WHICH IS REMOVABLY RECEIVED IN CORRESPONDING FRAME-BEARING MEANS PRIVIDED ON SAID SIDE ENDS OF SAID BRIDGE AND OF SAID BOOM WHEREBY EACH SHEAVE-SUPPORTING FRAME IS RECIPROCALLY TRANSFERABLY FROM SAID BOOM TO SAID BRIDGE AND VICEVERSA TO BY ONLY SUPPORTED BY EITHER OF THEM WHEN SAID SIDE END OF SAID BOOM MOVES PAST SAID CORRESPONDING SIDE END OF SAID BRIDGE, WHEREAS SAID SHEAVE-SUPPORTING FRAME IS SUPPORTED BY BOTH THE BRIDGE AND THE BOOM WHEN THIS LATTER IS ENTIRELY RETRACTED INSIDE SAID BRIDGE.