To suppress torque loss by sliding of components at metal contacted state in a reduction gear of a traction drive system.
In a reduction gear of a traction drive system constituted so as to transmit revolution of a planetary mechanism 5 to an output shaft 2 via a carrier 6 while rotating a rotary ring 3 in the reverse direction by a reversing mechanism 4 when an input shaft 1 rotates by providing the reversing mechanism 4 and the planetary mechanism 5 between the input shaft 1 and the rotary ring 3, the rotary ring 3 is prevented from sliding with the housing 7 and the carrier 6, and torque loss by sliding of the respective members at metal contact states is eliminated to obtain high torque transmission efficiency by positioning the rotary ring 3 in the shaft direction by a rolling bearing 13 provided with a cylindrical part of the housing 7 and holding the roll bearing 13 at a non-contact state with a cover part of an input side member 7a of the housing 7 and the carrier 6.
Higashio Masahiro
Takayoshi Tagawa