JERKER PUMP UNIT Russian patent published in 1995 - IPC

FIELD: oil extraction by means of jerker pumps. SUBSTANCE: pump unit has main pump 1 with through plunger 5 mounted in barrel 4, first auxiliary pump 5, second auxiliary pump 27; first one has auxiliary barrel 12 accommodating differential piston with smaller-diameter hollow stage 20 to form chamber 22 above piston and chamber 23 below piston, delivery valve whose outlet is essentially throttling hole 19 for communication of chamber 22 above piston with smaller-diameter stage of differential piston. EFFECT: improved design. 1 dwg