Manual dual clutch power transmission unit 10 for a vehicle (tractor, constructional vehicle and the like), which comprises a synchro-shuttle transmission unit 10S (forward/reverse drive transmission), a hydro-mechanical operated a dual clutch unit 10D, a multi-speed transmission unit 10T (8 speed transmission unit), a range transmission unit 10R (3 ranges—low range, medium range and high range), a hydro-mechanical transmission control mechanism 100 which controls shifting and selection of gears (odd gear and/or even gear) and corresponding clutches (odd clutch and/or even clutch) respectively, and an auxiliary transmission actuation mechanism 200 which actuates the power transmission unit 10 when at least one of the hydraulic dual clutch unit 10D of the power transmission unit 10 and a hydraulic system of the vehicle is not functioning, wherein the transmission control mechanism 100 for the multi-speed transmission unit 10T is provided with Z-gate sequential gear shift pattern.