Patent ID: 7523836

Claim:
A crane system for loading and unloading shipping containers from vessels moored at a dock said system comprising: (a) a crane frame mounted on the dock; (b) an elongated boom supported by said crane frame and including a first end disposed over the dock and a second end disposed over the vessel, said elongated boom comprising first and second spaced-apart boom elements, each having an upper portion and a lower portion; (c) a first pair of spaced-apart tracks carried by said upper portion of said first and second spaced-apart boom elements of said elongated boom; (d) a second pair of spaced-apart tracks carried by said lower portion of said first boom element of said first and second spaced- apart boom elements of said elongated boom; (e) a third pair of spaced-apart tracks carried by said lower portion of said second boom element of said first and second spaced-apart boom elements of said elongated boom; (f) a first trolley system carried by said first pair of spaced-apart tracks and movable along said tracks from a first position over the dock and a second position over the vessel, said first trolley system comprising upper and lower first spreaders interconnected by a first pair of spaced-apart cables for raising and lowering said lower first spreader and a turntable connected to said upper first spreader for rotating said upper and lower first spreaders through an angle of between 0 and 90 degrees; g) a second trolley system carried by said second and third pair of spaced-apart tracks and movable along said tracks from a first position over the dock and a second position over the vessel, said second trolley system comprising first and second carriages, a lower second spreader and pair of spaced-apart cables interconnecting said first and second carriages for raising and lowering said lower second spreader, said upper and lower first spreaders being movable between said first pair of spaced-apart cables of said first trolley system when said upper and lower first spreaders have been rotated through an angle of 90 degrees.