GB1264046A - Vertical load transfer - Google Patents

Abstract

1,264,046. Lifting and lowering; transshipping. FAIREY CANADA Ltd. 12 Aug., 1969, No. 40223/69. Headings B8B and B8E. Means for vertically transferring a load carrier 53 between a helicopter 1 and a ship 3 which are subject to vertical relative movements comprises a winch on the ship applying a constant tension to a cable 5 extending up for attachment to a freely rotatable drum 41 in the helicopter, a cable 51 attached to and wound on the drum 41 and extending down for connection to the carrier 53, and a cable 65 extending between the carrier and a haul-down winch 87 on the ship whereby the carrier can be forcibly lowered by the cable 65 against the constant tension in the cables 5, 51, which would normally raise the carrier. Both cables 5 and 65 pass around snatch shock absorbing devices 71 in the form of cable accumulators, each comprising sets of cable pulleys pneumatically or hydro-pneumatically biased apart. In operation, assuming the helicopter is supporting the carrier 53 through cable 51 anchored at 49 to the drum 41 which has a brake 43 applied thereto, and the cable 65 which is anchored to the carrier 53 by an electrically detachable shackle 57, has its free end coiled at 65A in the helicopter, a messenger cable is lowered from a winch 91 to pick up the free end of the cable 5 from the ship for connection at 45 to the drum 41, while the free end of the cable 65 is dropped or later lowered by the messenger cable, to the ship for connection to the device 71 and winch 87. The drum brake 43 is then released and the constant tension winch set in operation, after which the haul-down winch is started to pull down the carrier 53, any movement between the ship and helicopter being compensated for by the constant tension cable whereby the rate of change of position of the carrier 53 relative to the ship remains constant, any sudden movements of the ship being compensated for by the shock absorbers. The electrical shackle 57 for the cable 65 is controlled through a conductor cable 59 payed in and out by a winch in the helicopter and in an emergency is remotely disconnectable, guillotines 103, 105 also being provided to sever cables 5 and 51 in the emergency. The control system for the winches, Fig. 4 (not shown), includes a motor for the haul-down winch controlled by signals from a desired cable velocity control and an actual cable velocity transducer, whereby a constant velocity is maintained by correction, and an hydraulic motor for the constant tension winch which is controlled by setting a desired cable velocity or tension, the actual velocity or tension being sensed to provide correcting signals. A limit tension sensor is provided in the latter system to automatically switch the setting of the constant tension winch from velocity to tension control at a predetermined cable tension.