The utility model relates to an unipolar gear box contains a base, a CD -ROM drive motor, a reduction gear system and a power take off dish, the base has a top surface and a bottom surface, the CD -ROM drive motor has an output shaft, and output shaft an in output gear, reduction gear system provides in the bottom surface, and connects a transmission shaft, and the transmission shaft passes the base and protrudes the furthest in the top surface of base, and reduction gear system meshes in output gear, and a power take off dish, set up in the top surface to connect in the transmission shaft. The utility model provides an unipolar gear box, its simple structure and be favorable to miniaturizedly to supply the installation to needing the size little and operate in delicate gear drive's the outfit, make the utility model discloses a range of application is more extensive.