Abstract: Pump apparatus and method in which gaseous fluids that develop in the pumping chamber of a down hole pump can be removed during normal operation of the device to prevent gas-lock and to avoid having to force gases up the tubing string.

Abstract: A pumping apparatus includes a reversible variable displacement drive pump having two ports and a lifting apparatus connected to one of the ports. The lifting apparatus is designed to fit on the well-head of an oil well and attach to the polish rod of the well to operate a down-hole pump. A fluid accumulator containing a precharge is connected to the second port of the drive pump. A pump-off control system automatically adjusts the pumping rate of the lifting apparatus to the individual rate of formation flow of a particular well.

Abstract: A hydraulic fluid power system incorporating a supplemental pressurization system at the intake side of a hydraulic pump. The supplemental pressurization system includes a supplementary reservoir in communication with a primary fluid accumulator and an intake conduit of the hydraulic pump. The reservoir supplements hydraulic fluid flow to the intake side of the pump whenever intake line pressure drops below one atmosphere. Should the combined hydraulic fluid flow from the accumulator and the reservoir be insufficient to raise the intake pressure to prevent cavitation of the pump, an air ingestion valve opens to supply air to the intake side of the pump until proper pressurization is achieved, whereby the supplemental pressurization system closes off.