GB190930032A - Improvements in Hydraulic Machinery for Lifts, Hoists, Cranes and the like. - Google Patents

Abstract

30,032. Hammond, E. N., and Champness, H. Dec. 23. Ram apparatus; balancing. - Relates to the hydraulic lift &c. described in Specification 26,553/08, and comprises modified constructions in which two cylinders and two rams are used, one of which is weighted to overbalance a predetermined load and to displace fluid to the second cylinder without loss through a modified arrangement of control valves. As shown in Fig. 1, the two cylinders y, z have rams b, b<1> from which extension rods c, c<1> pass through the upper ends of the cylinders. The rod c attached to the weighted ram carries a sheave c<3>, the frame of which is connected to the rod c<1>. The load rope d is fixed at d<1> after passing round the pulley c<3>. The cylinders are connected to the valve apparatus near their upper ends by pipes f<5>, f<6>. The valve apparatus is shown in Fig. 5. Working within a casing p is a hollow spindle q operated by hand and provided with sets of perforations. The casing is provided with corresponding ports and passages and two valves w, w<1>. The pressure water enters at u and exhausts at u<1>, while two pipes lead from v and v<1> to the cylinders z, y as shown. In the position in which the valve rod q is shown, pressure water is shut off and communication between the two cylinders interrupted. The load is operated upon by moving the valve rod into different positions :-(1) To lift a light load, the weighted ram is allowed to fall and to pass fluid from the cylinder z to the cylinder y, pressure fluid being shut off ; (2) to raise a heavy load, pressure water is admitted to the cylinder y while the cylinder z is open to exhaust ; (3) to lower a heavy load, fluid is allowed to pass from the cylinder y to the cylinder z, the pressure fluid being shut off ; and (4) to lower a light load, pressure fluid is admitted to the cylinder z, the cylinder y being open to exhaust.