GB1162645A - Winch Control Systems - Google Patents

Abstract

1,162,645. Winches; transhipping at sea. K. A. OVRETVEIT. 4 Jan., 1967 [11 Jan., 1966], No. 1160/66. Headings B8B and B8E. A winch control system for controlling the tension in cable used to convey goods between relatively moving ships, comprises first and second winches SC, T driven by hydraulic motors 17, 18, a rotary valve 33 and drive motor 35 therefore for controlling the hydraulic supply to the first motor 17 in response to hydraulic pressure from an auxiliary hydraulic fluid supply pump 36, a compensating pump 52 gear driven by the second motor 18 and an auxiliary control valve 38 adapted to control the flow of fluid from the auxiliary supply to the motor 35. The latter is in fluid communication with the compensating pump 52. The speed control winch SC and the tension winch T are mounted on the deck of one ship and cables 5, 2 therefrom pass over elevated pulleys, the cable 5 being then coupled directly to one side of a goods carrier and the cable 2 passing around an elevated pulley on the other ship and back to be coupled to the other side of the carrier. The latter is suspended via a pulley, from the portion of cable 2 extending between the two ships. The control system facilitates maintaining a constant tension in the cables, a constant speed of transportation of the carrier relative to the two moving ships and a constant position of stopping of the carrier irrespective of the relative motions of the ships. The winch motors 17, 18 driving drums 19, 20 through friction clutches, are supplied with pressure fluid by pumps 14, 15. The winch motor shaft is coupled to the rotor of the valve 33 by gearing 34 for accurate synchronization of their motions. The rotating speed of the motor 35 controlled by the valve 38, controls the rotary valve 33 and hence the speed of the winch motor 17. If tension in the cable 2 or 5 causes an increase in fluid pressure in the winch motor supply lines 29, 30 or 26, 27, this increase operates a valve 41, via lines 42, 43 or 61, 62 to vary the supply of pressure fluid to the motor 35 and hence alter the speed of the winch motor 17 to relieve cable tension. When the motor 35 is not supplied with fluid via the valve 38, fluid is supplied thereto by the compensation pump 52 to drive the motor 35 at the same speed and in the same direction as the pump 52, whereby the winches SC and T are synchronized for paying out and winding in cable. During transfer of cargo, the winch motors 17, 18 rotate in opposite directions at the same speed, fluid being supplied to the motor 35 and compensator pump 52 from valve 38, in equal quantities. However, any change of speed of the winch motor 18 will cause, via the compensation pump, an equal but opposite change of speed of the winch motor 17. A clutch 47 automatically couples the motor 35 and pump 52, and stops fluid pump 36 upon manual operation of a lever to stop cargo transfer. Contactors 46, 49 axially movable through screws 45, 50 and gearing on the winch drums, move in proportion to the movement of the cargo carrier and control the fluid system to arrest the carrier as it reaches a fixed distance from either ship. When the cargo carrier is positioned over either ship, the associated elevated pulley is lowered by means of an hydraulic motor associated with each ship. As the pulley is lowered the system winds in the cables 2, 5 to maintain the carrier in a fixed position relative to the pulley.