Patent GB-491334-A (GB)
Title: Improvements in winches
IPC: B66D1/48
Filed: 1937-05-04
Abstract: 491,334. Winches. SMALTZ, J. C., and KAHLERTH, C. W. May 4, 1937, No. 12748. [Class 78 (v)] A winch, particularly for hoisting a floating object which is subject to a vertical &c. motion owing to wave action, has means for imparting constant tension to the hoisting cable after its attachment to the object and then converting the winch from constant cable tension to positive hoisting when the object is rising on a wave with maximum velocity, as judged by the operator. Fig. 1 shows a winding drum 21 driven by a pinion 23 on a shaft 24 carrying the planet cage of an epicyclic gear, the sun-wheel of which is fixed to a shaft 28 and the outer ring of which is formed on the inside of a brake drum 30. The shaft 28 is driven by a uni-directional constantly running electric motor 53, acting through reduction gearing 54 and through a pressure and manually controlled, variable speed, and reversible hydraulic pump 55 connected by piping 56 with a variable speed, reversible, hydraulic motor 57 of the automatic pressure regulated stroke type. The pump 55 is controllable also by a hand wheel 58 to start, stop, reverse and run the motor 57 at different speeds. Increase of pressure in the pump automatically reduces its stroke and increases the stroke of the motor 57 to reduce the hoisting speed to lift the full load. For constant tensioning the wheel 58 is adjusted to run the motor 57 fast enough to follow the combined wave motion and the roll of the ship. When upward movement of the object is approximately at maximum velocity, the planetary ring of the epicyclic will slow down owing to increased speed imparted to the hoisting drum by the planetary gears. Stoppage of the drum 30 is therefore an indication of the attainment of maximum speed at the drum and therefore of maximum upward wave speed. This condition is utilized both to indicate and to change operations automatically from constant tensioning to positive hoisting. Indication of the proper change-over condition is effected by an electrical graduated instrument 59 energized from a magneto generator driven through gearing from the drum 30, its drive depending on the difference in speed of the driving and driven means 28 and 30. Other gearing from the drum 30 drives the shaft 33 of a brake pump 34 which opposes rotation of the driving member 28. The energy developed by this pump driving constant tensioning operations is disposed of by passing the flow of oil &c. released by a pressure regulating valve 35 through piping 77 to a radiator 78 cooled by a fan 79. This cooling effect is not necessary when the winch is positively hoisting, and accordingly the fan motor is connected by wiring in parallel with the energizing circuit of a solenoid 48, Fig. 11, which controls the blocks 36, 37 which brake the drum 30. A booster pump 87 is provided when the pump 34 is of the gear type and subject to leakage at low speed. The valve 35 has an adjustable pilot valve and may be of the differential type, and the pumps 34 and 87 and valve 35 may be replaced by electric apparatus. For preventing reverse rotation of the brake pump 34 under the force of liquid supplied thereto by the booster pump 87 a ratchet wheel is fitted to the brake pump shaft 33 and is held by a pawl fitted with a spring-pressed drag contacting with flanges on each side of the ratchet wheel. Rotation of the ratchet in direction brings the pawl down in locking position on the ratchet wheel, and rotation in the opposite direction lifts the pawl clear of the ratchet wheel. The shaft 28 has an emergency hand brake 163 which may be automatically held by a spring fitted with a, releasing solenoid to apply both brakes 163 and 36, 37 when the machine is shut down. A wave selection switch 68 mounted on the end of the shaft 24 is operated by a cam which breaks a contact after a predetermined length of cable has been wound up.