DEEP-WELL PUMP PISTON Russian patent published in 2003 - IPC

FIELD: oil production from oil wells by means of deep-well pumps. SUBSTANCE: piston includes metallic tube having on outer surface annular grooves dividing tube by row of successive working cylindrical portions with working lateral surfaces. Annular grooves are formed on each end of working cylindrical portions. Solid ring-shaped inserts of metal whose hardness is less than that of surface coating of working surfaces of pump cylinder are rigidly mounted in said annular grooves. Outer diameter of inserts is equal to outer diameter of cylindrical portion of piston or exceeds it but no more than by value corresponding to gap of piston group mounting in pump cylinder. Ring-shaped inserts are made of non-ferrous metal such as bronze, brass. EFFECT: enhanced reliability of piston due to elimination of wear of working surfaces of cylinder, improved reparability of piston. 2 cl, 1 dwg