Patent ID: 6640986
Filing Date: 2003-11-04
Classification: B66C

Abstract:
A gantry crane comprising:a frame structure; a grappler movably suspended from the frame structure, the grappler having a platform and at least one pair of cooperating arms for lifting a load below the platform, the arms being mounted to the platform for pivotable movement on respective rotational axes which are parallel to each other, the arms being pivotable inwardly toward each other to clamp the load, the arms being pivotable outwardly away from each other to free the load; the grappler being laterally moveable relative to the frame in a generally horizontal direction perpendicular to said axes; a hydraulic system for moving the arms, including: a hydraulic actuator operably linked to pivot a respective one the arms; a first conduit in communication with the actuator such that fluid flows to the actuator through the first conduit to pivot the respective arm outwardly; a second conduit in communication with the actuator such that fluid flows to the actuator through the second conduit to pivot the respective arm inwardly; and at least one dampener operable to permit restricted flow through an associated one of the conduits away from the actuator caused by sway motion of the respective arm.