Abstract: A gantry crane travelable along a pair of rails and having an overhead girder transverse to the direction of travel, first and second legs connected to the girder, a load carrying trolley movable along the girder to a first position adjacent the first leg and to a second position adjacent the second leg, first and second spaced apart motor drives mounted on one of the legs in engagement with one of the rails for moving the crane, and third and fourth spaced apart motor drives mounted on the other leg in engagement with the other rail for moving the crane. When the trolley is at the first position, the first and second drives are highly loaded and the third and fourth drives are lightly loaded. Thereby, the lightly loaded drives attempt to drive the second leg such that it leads the first leg and skews the crane. When the trolley is at the second position, the third and fourth drives are highly loaded and the first and second motor drives are lightly loaded.

Abstract: The disclosure involves a material handling machine such as a lattice-type portal crane having an elongate lattice girder suspended from a girder beam by a first and second support links. In turn, the girder beam is supported at an elevation by a pair of legs. The improvement comprises a force transfer link coupling the support links so that forces transferred between the girder beam and either leg are isolated from the girder. The girder, which is triangular-shaped, has a top apex-like chord member and a pair of lower chord members. The support links and the force transfer link support the girder at the lower chord members and the top chord member is spaced (and therefore, isolated) from the girder beam.

Abstract: A reeving apparatus for a crane having an overhead frame, a lifting beam subject to swaying forces, and a winding drum mounted on the frame for raising and lowering the lifting beam. First, second, third and fourth spaced apart rotatable sheaves are mounted on the lifting beam for supporting the lifting beam. The first and second sheaves are spaced apart in directions horizontally transverse to a longitudinal axis of the drum. The third and fourth sheaves are positioned generally below opposite ends of the drum. Alternate ones of the sheaves comprise single sheaves having first and second grooves and the other ones of the sheaves each comprise a pair of sheaves each having single grooves. A plurality of ropes are affixed to the drum and to the overhead frame, and each one of the plurality of ropes is wrapped around one of the sheaves for supporting the lifting beam together with the sheaves.

Abstract: A latch for a crane travelable along a pair of generally parallel rails and having an overhead frame and a plurality of wheels engaging both of the rails for supporting the crane during its travel on the rails. The latch comprises a latch arm mounted on the crane and having a path of movement substantially in the direction of travel of the crane. The latch arm also includes a transversely projecting hook. A latch block is stationarily mounted and has a lip member projecting into the path of movement of the latch arm. The hook on the latch arm moves with the latch arm into engagement with the lip member and the lip member and hook have an engaged position in which the lip member is positioned between the hook and the crane whereby the crane is held from traveling away from the latch block. The latch may also include a compressible bumper mounted on the crane and engaging the latch block compressively in the direction of the crane travel toward the latch block.

Abstract: A reeving apparatus for a crane hoist is disclosed as having an overhead frame, a lifting beam positioned below the frame and carrying a plurality of rotatable lifting beam sheaves, and load carrying means suspended from the lifting beam. A plurality of ropes are also provided for supporting the lifting beam and load carrying means with each one of the plurality of ropes being wrapped around at least one of the plurality of lifting beam sheaves. A pair of rotatable drums are mounted on the overhead frame with the first drum being connected to the plurality of ropes for raising and lowering the lifting beam and the second drum also being connected to the plurality of ropes for raising and lowering the lifting beam. Although both drums are connected to the plurality of ropes, they are operable independently of each other to raise and lower the lifting beam in the event of inoperability of either drum.

Abstract: A truss connecting joint for a crane is disclosed in which the truss frame has parallel chord members each comprising two beams having I-shape cross-sections, a female ear having a pair of parallel spaced apart plates projecting from an end of one of the beams toward the other beam and a male ear including at least one plate extending from the other beam and positionable between the plates of the female ear. When the plate or plates of the male ear are positioned between the plates of the female ear, the two ears may be joined together by a member extending through the ears.The connecting joint may be positioned between two truss lace members which are perpendicular and affixed to two parallel chord members of the truss frame. Diagonal lace members are also affixed to the truss frame adjacent to the affixation location of the perpendicular lace members to the chord members.