OIL-WELL PUMP HYDRAULIC DRIVE Russian patent published in 2002 - IPC

FIELD: hydraulic machines. SUBSTANCE: device is designed for use in positive displacement hydraulic machines and drives including hydraulic or pneumatic means used for lifting liquids from depth. Proposed drive has working cylinder. I divided by piston 2 into piston space 3 and rod space 4 and pneumatic or hydropneumatic counter balancing system (tandem cylinder 5, reservoir 14) connected with rod space 4 of working cylinder. piston space 3 and rod space 4 of working cylinder 1 are interconnected by pipeline 19 with shutoff cock 20 to form closed hydraulic circuit. When carrying out servicing and repair of underground equipment, shutoff cock is opened and piston space 3 and rod space 4 of working cylinder 1 are connected to form closed hydraulic circuit, and piston 2 of working cylinder 1 moves downwards loosening the tension of string of sucker rods 23. EFFECT: improved reliability and safety of plant, increased economy. 2 cl, 1 dwg