Automatic differential starter of oil pumping machine

The invention belongs to mechanical equipment, and particularly relates to an automatic differential starter of an oilfield oil pumping machine. The automatic speed-difference starter of the oil pumping machine is used for solving the problems that existing planetary speed-changing starters are complicated in structure, high in manufacture cost, high in failure rate and not convenient to operate and repair. The automatic speed-difference starter of the oil pumping machine structurally and mainly comprises a box body, an input shaft, an output shaft, a transmission shaft, an operating rod, a belt wheel, a speed-adjusting gear, a movable tooth disc, an electromagnetic valve and a relay. The transmission shaft is provided with a big gear and a small gear which are used for reducing speed and increasing torque output during starting. The output shaft is provided with the speed-adjusting gear and the movable tooth disc. The relay is used for controlling starting of the electromagnetic valve and a motor. The electr