There are two different barrels and plungers in series connection. According to the theory of  hydraulic feedback, during the down stroke, a downward force is formed to overcome the friction between the viscous crude and the sucker rod, thus improving the load condition on the sucker rod and decreasing and eliminating the disconnection and break of the sucker rod. The pump applies to the wells of oil viscosity less than 4000 mpa·s(50°C), the wells with thin oil and the viscous oil wells without thermal recovery conditions.

Technical specifications