Abstract: An air transportable gantry-type crane has a pair of collapsible side frames adapted to be releasably interconnected by a pair of elongate cross members. Each side frame has an extended operating state and a collapsed transportable state. One of the cross members includes relatively short transversely extending coupling members adapted to interconnect the side frames for maintaining the same in closely spaced parallel relation. Each side frame is also provided with wheels and a support for supporting each side frame when disconnected from the cross members.

Abstract: A spreader assembly includes a frame and first and second spreader arms each including a pair of parallel spaced-apart beam members. The beam members are equal in length to each other and to the frame and each beam member has vertically spaced-apart rails. The frame also includes first and second pairs of bearings disposed above the horizontal center and on one side of the vertical center of the frame and third and fourth pairs of bearings disposed below the horizontal center and on the other side of the vertical center of the frame. In addition, the first and third pairs of bearings are disposed on the frame closer to the vertical center than the second and fourth pairs of bearings and the second and third pairs of bearings are disposed closer to the horizontal center of the frame than first and fourth pairs.

Abstract: A steering system for a gantry-type crane includes a hydraulic cylinder coupled to each wheel and operable to turn the same through at least a right angle. A hydraulic control system includes a first control valve having a two-wheel steering mode for connecting a first pair of cylinders to a pressure source and in a series relation with each other for two-wheel steering and having a four-wheel mold for connecting the first pair of cylinders in a parallel relation with each other for four wheel steering. A second control valve means has a two-wheel mode for isolating a second pair of cylinders from the pressure source and a four-wheel steering mold for connecting the second pair of cylinders to a pressure source. The first and second control valve means are selectively operable for sequentially moving each of the pairs of cylinders between their first and second steering modes.

Abstract: A straddle type mobile crane has a pair of hydraulic motor driven front wheels which may be pivoted about a vertical axis for steering. Each motor is supplied by an individual source of pressurized fluid which may be interconnected by a pair of adjustable control valves. A turning crank at each wheel engages a cam coupled to a respective one of the valves so that the hydraulic motors are coupled when the wheels are pivoted through predetermined angles.