Double acting self-flushing pump

Abstract

A double action slurry pump is provided having a shelf-flushing piston assembly mounted in a mating cylinder. The piston assembly includes a first piston having a peripheral sealing means and a reciprocating piston rod for driving the first piston. Second and third power pistons mounted adjacent opposite sides of the first piston include sealing discs and form respective first and second chambers with the first piston and the adjacent cylinder wall. The second and third power pistons serve to pump the slurry on the sides opposite the flushing fluid chambers. Each of the pumping pistons includes hollow carriers that cooperate with shoulders fixed to the piston rod to provide limited lost motion movement. The resulting lost motion serves to vary the size of the first and second chambers. During the stroke of the piston assembly in one direction, feed lines in the piston rod provide flushing fluid to the expanding second chamber. As this occurs, the first chamber contracts and fluid is forced in a peripheral sweeping fashion from the second chamber past the sealing disc of the second piston and into the slurry. During the reverse stroke, fluid enters the expanding first chamber while being forced past the third piston from the contracting second chamber. The flushing fluid sweeping around the sealing discs of the power pistons clears the aggregate material preventing abrasive wear to the sealing disc and the cylinders.

Dependencies are inferred from the claim text.