Abstract: A slurry pump has slurry hopper and dual pumping cylinders. The slurry pumping members are driven by opposite-phase actuators. Each actuator has a rigid-hollow-stem partition dividing the space between the actuator plunger and the cylinder into two drive chambers of different areas selectively supplied with pressurized fluid to drive the plunger with a selected force and speed. An associated valve shuts off flow to one of the drive chambers and is controlled at any given time to occupy the same position as a corresponding valve of the other actuator. The valves coordinate supply of fluid to corresponding drive chambers on alternate strokes of two actuators.

Abstract: A slurry pump has a hopper containing slurry. A pumping cylinder containing a piston communicates with the hopper through the hopper wall. A delivery tube is swung into and out of register with the cylinder. Slurry is drawn into the cylinder by the piston and out through the delivery tube. The pump is controlled by a lever which has a central neutral position and two operating positions.Dangerous moving parts are covered by a guard mounted on hinges. An arm on the guard engages a slide which has a channel. If the guard is moved from its closed position, the arm slides the slide so that the control lever enters the channel and moves to its neutral position. The external moving parts include releasable clamping means for sealing the junction of the delivery tube and the cylinder while slurry is being transferred from the cylinder to the tube.