Diameter-adjustable & moment-variable series energy-saving pumping unit is technically innovated on the basis of the beam-pumping unit, namely the beam realizes offset balance, medium & small-sized units adopt a rear-mounted structure, and large units adopt a front-mounted structure, which changes the traditional balance mode and realizes good balance. Balance adjustment=addition/reduction of small balancing weights + diameter adjustment & moment variation. By exchanging the reducing pins with different diameters, the included angle between the suspension arm and the walking beam can be changed; meanwhile, the maximum counterbalance moment position of the counter weight can be adjusted by changing the motion track of the counter weight, thus accurately adjusting the balance according to the peak position of the load. It is easy to adjust, namely middle & small balance weights are extremely easy to add and reduce because the weight box is close to the ground at the dead point of the horsehead. In the stroke adjusting process, the walking beam and the bracket are locked, thus changing the current situations such as poor safety, high labor intensity and crane requirements for wells in the past stroke adjusting operation and other auxiliary operations.
