Double winch crane for backlash-free lifting and cross travel - has ropes over diverter-sheaves on crab to lifting device to operate both cross travel and lift load

摘要

Two double grooved rope winches (2) are mounted one each end of the bridge (1). The ropes (3) pass over diverter sheaves (4) on the crab (5) and down to a point (7) on the load carrying attachment (6). To lift or lower the load both ropes are wound in or out. To operate the cross travel one rope is paid out while the other one is wound in. Data from an angle encoder on each winch is fed to an evaluator to indicate the position of the load. ADVANTAGE - No slack rope condition arises either during cross travelling or load lifting and lowering.