US Patent 10962000 Long stroke pumping unit

A long stroke pumping unit includes a tower and a counterweight assembly movable along the tower. A belt includes a first end connected to the counterweight assembly and a second end connectable to a rod string. A prime mover is used to reciprocate the counterweight assembly along the tower. A sensor detects the position of the counterweight assembly, and a load cell measures the force exerted on the rod string. A motor is provided to adjust an effective weight of the counterweight assembly during reciprocation thereof along the tower. A controller communicates data with the sensor and the load cell and controls the adjustment force exerted by the adjustment motor.