Hydraulic operated surface pumping unit

摘要

The hydraulic operated surface pumping unit of this invention is a counterbalanced cross beam type pumping unit driven by a hydraulic cylinder. The pumping unit can be operated in a first mode of equal upstroke and down stroke speeds or in a second mode of slower upstroke and faster down stroke speeds. The stroke lengths are controlled by cams and are adjustable over a large range. Stroke cycle speeds can be varied by adjusting the output rate of a hydraulic pump used to drive the system. The main hydraulic valve includes intermediate lock positions to hold the pumping unit steady during phase shifts between upstrokes and down strokes and during shut down of the pumping unit. Pressure indicators are provided for optimum counterbalancing of the pumping unit, and a needle valve control for return fluid flow to tank is provided for slow let down of the pump rod for initial tag out settings. A combination oil tank and cooling unit has an overflow bypass to insure the hydraulic pump is not starved of hydraulic fluid in cold weather start up.