GB318637A - Improvements in or relating to hydraulic lifting and pulling jacks - Google Patents

Abstract

318,637. Wrona, C. Sept. 8, 1928, [Convention date]. Cam-actuated pumps; single-acting bucket pumps; single-acting suction-valveless piston pumps; pipes; plungers.-A hydraulic jack comprises a ram working in a cylinder, valve controlled passages and a pump having a plunger operated by a rocking handle and a screw and nut device or by a rocking handle and pivoted lever, the ram and plunger being mounted in tandem on a common base and having a single control value. The pump comprises a stepped cylinder R<1> in which is arranged a stepped plunger P<1> provided with a handle L. By rocking the ha.ndle the plunger is reciprocated by means of screwed flanges P<4>, Fig. 7, engaging a screwed collar <p5> carried by the reservoir K. The plunger cylinder R<1> is provided with a passage f controlled by a valve N which can be set to allow the pressure fluid to pass into the ram cylinder through a passage, not shown, leading to the bottom of the ram cylinder, to raise the ram, or through a passage f<11> leading to a space U surrounding the ram so that it acts on the annular enlargement C at the bottom of the ram and forces the ram downwards. The stepped plunger P<1>, Fig. 7, has transverse ports f<14> and is fitted with a central control rod T which can be set by means of a knob j to put one or more parts of the stepped cylinder into communication with the reservoir according to the pressure required. In a modification the pump has a single plunger J, Fig. 15, actuated by a tappet rod 1, pivoted lever 2 and rocking arm 4, a spring 5 returning the plunger on the inoperative stroke. A passage J<1> in the plunger admits fluid into the cylinder H, the pressure fluid passing into the ram cylinder A through a valve 7 and passage b<1>. To lower the ram the valve is set so as to connect the pump to the annular space U around the ram and the bottom of the ram cylinder to the reservoir.