GB324093A - Improvements in hydraulic cranes, lifts and other hydraulically actuated devices or apparatus - Google Patents

Abstract

324,093. East Ferry Road Engineering Works Co., Ltd., and Kibbler, H. Oct. 15, 1928. Presses.-Relates to hydraulic cranes, lifts, or other machines provided with means whereby the quantity of fluid is varied substantially in proportion to the load. The main cylinder a communicates with a supplementary cylinder d in which a ram c operates at a lower pressure and actuates the main ram b under light loads, e.g. when raising a crane hook without load. The ram c is operated by high-pressure water acting on an auxiliary ram h in a small cylinder i. The cylinders exhaust to a flooding tank or to a standpipe, and the cylinder d draws water from the tank f or standpipe through a non- return valve g when the ram c falls. Both cylinders i, a are controlled by a shaft n operating the main inlet valve k and the exhaust valves l, m. A valve p between the cylinder i, a is set to open at a given pressure in order to control the operation automatically according to the load. On opening the main inlet valve k full pressure is admitted to the cylinder i and the water in d is placed under low working pressure for raising the ram b, but if the ram b is under load the pressure in the cylinder a acting beneath a piston q opens the valve p and high-pressure water is admitted to the cylinder a. The valve p may be opened proportionately to the load and it may be opened by a tappet r and lever s when the ram c reaches the top of its stroke. The exhaust valve l may be given a lead over the exhaust valve m. allowing the rams c, h to fall to the bottom of their strokes before the main ram b is right down.