A transmission, including an outer shell (1), an inner shell (2), a drive disk (3), a plurality of T-shaped teeth (4), a gear (5), a tooth seat (6), an adjustable nut (7), balls (8), inner balls (9), outer balls (10), an inner protective frame (11), an outer protective frame (12), rollers (13), a first sealing ring (14), a second sealing ring (15) and a third sealing ring (16). Transmission clearance can be adjusted freely at any time, the meshing of the T-shaped tooth and the gear is a real surface meshing, and almost all the teeth participate in force transmission simultaneously. Therefore, the transmission has high precision, high mechanical properties, and long service life.