Underground pump transmission, esp. for use in oil industry

摘要

The transmission drives an underground pump, esp. at an oil well, and is connected rigidly to a riser string. It is driven hydraulically, and a pump can be suspended in it. The transmission may have a jacket pipe (2) with upper and lower string connections (1), and the central section of the pipe may form a hydraulic cylinder (30). A piston (6) may be guided in the latter, and may be associated with upper (71) and lower (72) extension pipes. The piston and the extension pipes may also form an upper (31) and lower (32) hydraulic chamber with the cylinder.