FIELD: oil industry. SUBSTANCE: plunger has rod 1, whereon bushings 2 provided with spherical end faces are mounted with a spaced relation, and disconnectors 3 on the end faces of which the inner cones or spherical surfaces of radius no less than the radius of the spherical surfaces of bushings 2 are provided. Bushings and disconnectors 3 are tightened with the use of clutches 5 and 6 through flexible member 4, e.g. a spring. The inner diameter of disconnectors 3 and 7 are provided with grooves for sealing rings 11. EFFECT: enhanced reliability. 2 dwg
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