Gear box

The invention provides a gearbox, and belongs to the technical field of machinery. The gear box solves the problems that when an existing gear box is manufactured, output shafts of different numbers cannot be selected, manufacturing is inconvenient, and the application range is not wide. The gear box comprises an upper box body, the upper box body is provided with an installation cavity, a center shaft is arranged in the middle of the installation cavity, a fluted disc is fixedly connected to the center shaft in the axial direction, an input shaft is arranged on the upper box body in a penetrating mode, an input gear is arranged on the input shaft, the outer side of the center shaft is sleeved with a lower box body, the fluted disc is fixedly connected with the lower box body, and the lower box body comprises an upper cover body and a lower cover body. A plurality of mounting blocks are arranged between the lower cover body and the upper cover body, horizontal mounting holes are formed in the middles of the m