Large-torque main shaft transmission device

The invention discloses a large-torque main shaft transmission device, and aims to provide a large-torque main shaft transmission device capable of changing torque in stages, the main shaft transmission device is characterized by comprising a motor, a motor base is arranged at a motor outlet, the motor outlet penetrates through the motor base to the outside, and a transmission main shaft is further arranged on the motor base and located on one side of the motor outlet; a gear shaft A is further arranged at an outlet of the transmission main shaft, a telescopic rod is further arranged on the motor base and provided with a gear shaft C meshed with the gear shaft A, the gear shaft C comprises an upper gear and a lower gear integrated with the upper gear, the diameter of the upper gear is larger than that of the lower gear, a transmission connecting rod is further arranged on one side of the motor base, and a gear shifting oil cylinder is further arranged on one side of the motor. A gear shaft B is further arrang