Patent ID: 9228574
Filing Date: 2016-01-05
CPC Classification: F04B

Claim Text:
1. A pumping system comprising: a casing including a retraction end and a pumping end with a sidewall disposed therebetween, the retraction and pumping ends and the sidewall defining a piston chamber, the piston chamber accommodating a piston reciprocatable within the chamber between a retraction portion disposed between the piston and the retraction end of the casing and a pumping portion disposed between the piston and the pumping end of the casing; the sidewall including a retraction spill port that extends into the sidewall annularly about the retraction portion of the piston chamber and a pumping spill port that extends into the sidewall annularly about the pumping portion of the piston chamber; the casing including a first hydraulic passageway disposed between the retraction spill port and the retraction end of the casing and that is in communication with a hydraulic fluid reservoir separate and apart from the casing, the casing sidewall including a second hydraulic passageway disposed between the pumping spill port and the pumping end of the casing and that is in communication with the hydraulic fluid reservoir; the piston including a retraction spill passage configured to cooperate with the retraction spill port to provide communication from the pumping portion of the piston chamber and the retraction spill port when the piston is in a first position, the piston including a pumping spill passage configured to cooperate with the pumping spill port to provide communication from the retraction portion of the piston chamber and the pumping spill port when the piston is in a second position.