Patent GB-987993-A (GB)
Title: Hydraulically operated reciprocating pump for the transport of viscous, pulpy or plastic material
IPC: F04B53/14
Filed: 1961-07-27
Abstract: 987,993. Reciprocating pumps. F. W.SCHWING. July 27, 1961 [Aug. 8, 1960], No. 27203/61. Heading F1A. In an hydraulically operated reciprocating pump for viscous, pulpy or plastic material, for example concrete, at least one hydraulic actuating cylinder drives the pistons in two delivery cylinders via a piston rod so that one piston performs its suction stroke whilst the other performs its pressure stroke, mechanical, electrical, or hydraulic means actuate valve means for alternately connecting the delivery cylinders to the intake and delivery lines when the delivery pistons are in their end positions, and a flushing liquid is fed into each delivery cylinder behind the piston during a pressure stroke and is expelled therefrom during a suction stroke. In the embodiment in Figs. 3 and 4 the pistons 2, 2<SP>1</SP> in delivery cylinders 16, 16<SP>1</SP> are driven by pistons 27, 27<SP>1</SP> in hydraulic cylinders 20, 20<SP>1</SP> alternately connected at their left-hand ends to a pressure source via a control valve 22<SP>1</SP> and interconnected at their right-hand ends, so that the pistons 27 and 27<SP>1</SP> therein are caused to move in opposite directions. The valve 22<SP>1</SP> is operated by a rod 25 attached to a piston reciprocated in a cylinder 24<SP>1</SP>, the ends of which cylinder are alternately connected to a pressure source via a control valve 22 when stops 21, 21<SP>1</SP> on a lever are alternately engaged by projections 19<SP>1</SP>, 19 associated with the delivery pistons 2<SP>1</SP>, 2. The piston in the cylinder 24<SP>1</SP> causes a flat slide valve 17<SP>1</SP> to alternately open and close outlet branches 12, 12<SP>1</SP> of the delivery cylinders 16, 16<SP>1</SP>. Further, a piston in a cylinder 24, also connected to the control valve 22, causes a flat slide valve 17 to alternately open and close inlets to the cylinders 16, 16<SP>1</SP> to supply material thereto from a hopper 11. The delivery cylinders 16, 16<SP>1</SP> are flushed by water delivered to them from a storage tank 8 during the pressure strokes and expelled to a settling tank 10 during the suction strokes of the pistons 2, 2<SP>1</SP>. For transportation of the pump a valve 30 allows the pistons 2, 21 to be positioned simultaneously at the ends of their pressure strokes. In an alternative embodiment, Fig. 5, the pump has two parallel hydraulic actuating cylinder 20 which are coaxial with their respective delivery cylinder 16 but are separated therefrom by the water storage tank 8. The pump is mounted on a frame 31 having a collapsible support and an axle for road wheels. The material is fed from a hopper 11 to the cylinders 16 and is delivered thereby through a cranked outlet connection 32 which is rotatable in a bearing by a lever 34, adjusted by an hydraulic cylinder 37 to alternate between cylinders 16. The connection 32 has agitator arms 38 and rigid or flexible scrapers 39. Pipe connections 50 permit introduction of liquid or powdered admixture for modifying the composition of the material being pumped. The hydraulic cylinders 20, 37 are supplied via a control box 49 with oil under pressure by a separate motor-driven, controllable pressure-generator which may be mounted on the frame 31. Additionally, the oil may pass through pressure operated reversing valves to the cylinders 20, 37, to immediately reverse the movement of the delivery pistons 2 if there is a sudden pressure rise due, for example, to a momentary congestion in the delivery pipe. An amount of reserve travel for the pistons in the hydraulic cylinders 20 enables the pistons 2 to be pushed into the water tank 8, which is freely accessible from the top, for inspection and renewal, the rods 1 being mushroomed at the piston ends for quick assembly of the pistons 2. The water in the tank 8 may be drained off at 41 and any sediment in the tank removed through openings 42. The tank 8 has a vertical partition, Fig. 11, so that when a removable horizontal plate having valves 47 is fitted, the flushing water is pumped by the pistons 2 through non-return valves 44 to a conduit 48 which may be attached to the delivery pipe 321 for cleaning thereof. In another embodiment, Fig. 1 (not shown), the delivery cylinders are axially aligned and arranged on either side of an hydraulic actuating cylinder, the pistons of the delivery cylinders being connected at opposite ends of a piston rod passing through the actuating cylinder, and the axially outer ends of the delivery cylinders each have an hydraulically controlled rotary valve which alternately connects the delivery cylinder with an inlet branch and an outlet branch. In a further embodiment, Fig. 2 (not shown), a single rotary valve separates two axially aligned delivery cylinders each provided with an actuating cylinder, the valve alternately connecting the delivery cylinders to the inlet and outlet passages.