Pump jack assembly for wells

In a pump jack assembly for wells which include a polish rod operating a pump within the well and a source of hydraulic fluid under pressure including a fluid reservoir;

• the improvement comprising in combination a separate pump actuating assembly having a lift stroke and a return stroke and including at least one fluid operator operatively connected to the polish rod, and a separate counter balance assembly including at least one fluid operator, also operatively connected to the polish rod, said fluid operators including a lift side and a return side, means operatively connecting the source of hydraulic fluid under pressure, to the lift side of said fluid operator of said pump actuating assembly when said pump actuating assembly is on the lift stroke, and to the return side of said fluid operators of said pump actuating assembly and said counter balance assembly when said pump actuating assembly is on the return stroke, said connecting means being responsive to the position of said pump actuating assembly to effect a cycling operation of said pump jack assembly, and a fluid source having means to adjust the pressure thereof and being operatively connected to the lift side of the fluid operator of said counter balance assembly, said fluid source having adjustable pressure including an accumulator having a liquid in the lower portion thereof and gas under pressure in the upper portion thereof, said liquid being operatively connected to the lift side of the fluid operator of said counter balance assembly, a source of high pressure gas, a one-way high-to-low pressure regulator valve between said source and the upper portion of said last mentioned accumulator, and adjustable means operatively connected to the hydraulic pressure acting on the lift side of the fluid operator of said pump actuating assembly and said regulating valve for operating said regulating valve.