PUMPING UNIT Russian patent published in 2007 - IPC F04B47/02 

FIELD: oil production from well, particularly well sucker-rod pump drives.

SUBSTANCE: pumping unit comprises driving assembly including two parallel reducers with common shaft and output shaft connected with each other. Differential crank translating mechanism is installed on output shaft of each reducer. Flexible member of rod carrier bar has the first branch passing over tension pulley of leading crank of one reducer translating mechanism through guiding pulleys fastened to post cross-arm. Another flexible member branch passes over tension pulley of another reducer translating mechanism. Flexible mechanism passes over pulley movably installed in lower cross-arm part and defines tackle loop. In another embodiment each flexible member branch is fastened directly to movable fastening assembly on leading crank. Reduction-ratio of reducers is equal to crank arm reaches. Cranks are installed in the same initial position. This provides synchronous leading crank rotation. Force is transmitted from one reducer and crank with balancing weights to each flexible member branch.

EFFECT: increased driving force, increased travel length of pumping unit.