Hydraulically operated cranes

Claim 1

A hydraulically operated crane comprising a support structure having a hollow cylindrical travelling bridge, trolley tracks on said cylindrical travelling bridge to support the trolley to a side of said travelling bridge, a hoist block supported from said trolley, a balanced fleet through rope and reeve system supported by said structure to control the lifting and lowering of the hoist block, a hydraulic multiplying linear motor having one end anchored in the support structure to provide operating power for the hoist block, said linear motor having twin opposed hydraulic cylinders, tie rods connecting the cylinders in line with the length of tie rods between adjacent ends of the cylinders determining the operating stroke of the linear motor, a reeve sheave carrier connected in the space between the cylinders to each operating piston extending from the cylinders, two reeve sheaves mounted on said reeve sheave carrier, end return sheaves at each end of said support structure, two trolley sheaves mounted on said trolley and a diverter sheave supported in said support structure with the operating rope for the hoist block having the ends anchored to a support base associated with the linear motor with the rope from one anchor point passing about one reeve sheave mounted on the reeve carrier supported by the pistons of the linear motor, and the end return sheaves at the end of the structure before being returned to the trolley sheave and about the hoist block and the rope from the other anchor point passing about the second reeve sheave on the reeve carrier supported by the pistons of the linear motor and about the diverter sheave before returning to pass about the end return sheaves at the opposite end of the structure and then to the second trolley sheave about the hoist block.