Load maneuvering apparatus

Claim 1

HOISTING APPARATUS FOR TRANSFERRING A LOAD BETWEEN TWO STATIONS WHILE SAID STATIONS ARE SUBJECT TO RELATIVE VERTICAL MOTION BETWEEN EACH OTHER, SAID APPARATUS COMPRISING LOAD MOVING MEANS INCLUDING ADJUSTABLE SPEED REVERSIBLE DRIVE MEANS, SAID DRIVE MEANS INCLUDING A MOTOR LOCATED ON ONE OF SAID STATIONS FOR MOVING SAID LOAD, CONTROL MEANS COUPLED TO SAID DRIVE MEANS FOR CONTROLLING THE DRIVE MEANS TO MOVE SAID LOAD IN A DIRECTION AND AT A SPEED IN ACCORDANCE WITH SIGNALS SUPPLIED TO SAID CONTROL MEANS, MEANS FOR PROVIDING AND SELECTIVELY SUPPLYING TO SAID CONTROL MEANS EITHER OF FIRST AND SECOND COMMAND SIGNALS, SAID FIRST COMMAND SIGNAL BEING OF ONE SENSE AND A PARTICULAR MAGNITUDE FOR COMMANDING THE CONTROL MEANS TO OPERATE SAID DRIVE MEANS TO MOVE THE LOAD IN THE HOIST DIRECTION AT A PARTICULAR SPEED RELATIVE TO THE OTHER OF SAID STATIONS, SAID SECOND COMMAND SIGNAL BEING OF OPPOSITE SENSE AND A CERTAIN MAGNITUDE FOR SAID DRIVE MEANS TO MOVE THE LOAD IN THE LOWERING DIRECTION AT A CERTAIN SPEED RELATIVE TO SAID OTHER STATION, MEANS RESPONSIVE TO THE RELATIVE MOTION BETWEEN SAID STATIONS FOR SUPPLYING A FIRST SPEED SIGNAL PROPORTIONAL TO THE SPEED OF SAID RELATIVE MOTION TO SAID CONTROL MEANS IN SAID ONE SENSE WHEN THE RELATIVE MOTION IS IN A DIRECTION TENDING TO CLOSE THE GAP BETWEEN THE LOAD AND SAID OTHER STATION, AND IN SAID