input shaft 2 which is also the output shaft of the gear mechanism of the automatic gear transmission assembly 1 also included in the transfer mechanism is a governor valve 3 fixedly mounted on the input shaft 2 a planetary gear set 4 having a sun gear 41 splined on the input shaft 2 a pinion 42 meshed with the sun gear 41 a ring gear 43 meshed with the pinion 42 and a carrier 44 rotatably supporting the pinion 42 and coupled with one output shaft 11 of the torque transfer mechanism the transfer mechanism also includes a friction brake 5 for engaging the ring gear 43 with a transfer device casing 18 a hydraulic servo motor 50 for the friction brake 5 comprised of a cylinder 18a formed in the transfer device casing 18 and a piston 51 slidably fitted in the cylinder 18a a friction clutch 7 operated by a hydraulic servo motor 70 comprising an annular cylinder 71 connected to the carrier 44 and a piston 72 slidably fitted in the cylinder 71 for coupling and uncoupling the sun gear 41 and the carrier 44 the transfer mechanism further includes a friction clutch 8 for coupling the output shaft 11 connected to the carrier 44 with a sleeve 9 connected to one of the sprockets 12 of a linkage mechanism which drives the other output shaft 17 of the transfer mechanism as will be described hereinafter also included in the transfer mechanism are a hydraulic servo motor 80 comprising a cylinder 81 welded to the sleeve 9 which is rotatably retained in the transfer casings 19 20 and a piston 82 slidably fitted.