Abstract: Disclosed is a transmission, which makes it possible to conduct work of repairing or replacing a braking device by disassembling only parts of a reduction gear system after separating a housing, and in which oil is provided around the braking device and circulates along a flow path, thus preventing the braking device from wearing, thereby extending the lifetime of bearings and gears. The housing is separable at a point between a driven gear and a planetary gear assembly.