High-bearing, small-return-difference and small-size vertical transmission speed reducer

The utility model discloses a high-bearing, small-return-difference and small-size vertical transmission speed reducer. The device comprises a precision speed reducer, a motor, a motor connecting baseand an input gear shaft sleeve, the motor is fixed at the top of the speed reducer through a motor connecting base; an input motor shaft of the motor penetrates through the motor to be connected withthe base. The input gear shaft sleeve is fixedly connected to an input motor shaft; the input gear shaft sleeve is tightly fixed on a shaft key of the input motor shaft through a jackscrew; wherein the front end of the input gear shaft sleeve is connected with an input gear in the speed reducer, a fastening ring is arranged on the input gear shaft sleeve at the joint in the speed reducer, a lip-shaped oil seal is arranged on the outer wall of the fastening ring close to the inner side of the speed reducer, and a check ring for preventing the oil seal from axially displacing is sleeved on thefastening ring close to the