Container ship cranes

Claim 1

IN A CONTAINER SHIP HAVING SPACED APART RAILS ADJACENT EACH EDGE OF THE DECK PARALLEL TO THE CENTER LINE, A CRANE STRUCTURE ADAPTED TO MOVE ON SAID RAILS COMPRISING A MAIN FRAME EXTENDING TRANSVERSELY OF THE SHIP, LEG MEANS ON THE ENDS OF SAID FRAME HOLDING THE FRAME VERTICALLY ABOVE THE SHIP DECK, DRIVE MEANS CARRYING THE LEG MEANS ON THE RAILS ON THE DECK, AN EXTENSIBLE GIRDER MEANS MOUNTED FOR MOVEMENT ON THE MAIN FRAME TRANSVERSE TO THE CENTER LINE OF THE SHIP FROM ONE EXTREME POSITION WHERE THE EXTENSIBLE GIRDER EXTENDS OVER ONE SIDE OF THE SHIP TO AN OPPOSITE EXTREME POSITION WHERE THE OPPOSITE END EXTENDS OVER THE OPPOSITE SIDE OF THE SHIP, A LOAD TROLLEY MOVABLE ON SAID EXTENSIBLE GIRDER FROM ONE END TO THE OTHER, A MACHINERY TROLLEY MOVABLE ON THE EXTENSIBLE GIRDER, CONNECTIONS BETWEEN THE MACHINERY TROLLEY AND THE LOAD TROLLEY WHEREBY THE TWO TROLLEYS MAY BE SELECTIVELY POSITIONED IN ANY ONE OF A PLURALITY OF POSITIONS WITH RESPECT TO ONE ANOTHER TO SET UP A GIVEN OPERATIVE RELATIONSHIP BETWEEN THE MACHINERY TROLLEY AND THE LOAD TROLLEY AND THEREAFTER THE LOAD TROLLEY AND MACHINERY TROLLEY ARE MOVED IN UNISON SO THAT THE MACHINERY TROLLEY COUNTERBALANCES THE LOAD TROLLEY, AND DRIVE MEANS MOVING THE EXTENSIBLE GIRDER, THE LOAD TROLLEY AND THE MACHINERY TROLLEY IN COOPERATIVE RELATIONSHIP.