To provide a more simple and economical solving means to completely eliminate conventional disadvantage and additionally change a rigging device of a block.
The device enables a switch from a pulley blocks being rigged with one strand to the pulley blocks being rigged with two strands and vice versa. The jib tip has a pulley movable along its axle between a central position, when the blocks are rigged with one strand, and a lateral position, when the blocks are rigged with two strands. The lifting block, with housing of symmetric shape, comprises a pulley and retractable guide means for the lifting cable. When the blocks are rigged with two strands, the end of the cable is connected to a point of attachment situated on the jib tip, on the opposite side to the lateral position of the pulley. When the blocks are rigged with one strand, the end of the cable is connected to a point of attachment situated on the pulley block. The device for changing the rigging of the blocks applies mainly to luffing cranes.
Takao Hamano
Morita Tetsuji
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