GB850425A - A hydraulic circuit embodying a combined pump and control unit - Google Patents

Abstract

850,425. Rotary pumps. THOMPSON GRINDER CO. Aug. 18, 1958, No. 26522/58. Class 110 (2). A worktable 10, Fig. 1, is reciprocated at substantially constant speed by a - piston and cylinder unit 16, 20 controlled by a reversing valve 24 which is connected to the outlet side of a variable-capacity pump 30 through a conduit 28 having a throttle valve 50. The control member 32 of the pump is urged to the maximum stroke position by an adjustable spring-loaded plunger in opposition to a plunger 42, 48 subjected to the differential pressure across the valve 50. In a modification, Fig. 2 (not shown), the right-hand side of the plunger 42, 48 is connected directly to the working chambers of the pump. The stroke of the plunger 42, 48 may be limited by an adjustable stop, see Fig. 3 (not shown). In a further modification, Fig. 4, the left-hand side of the plunger 82 is connected to the outlet conduit of the pump upstream of the throttle valve 94 and said conduit is provided with tappings controlled by a manually-operable valve 96 and a relief valve 92, as shown. In a final modification, Fig. 5, the delivery conduit of the pump 100 is connected to motors M1, M2 through throttle valves 104, 108 add reversing valves 106, 110 and is additionally connected to the left-hand side of the control plunger through check-valves 114, 122, as shown.