The structure characteristics of the combination of main and auxiliary box design, main box hand operation, sub tank gas operation, 8 forward and 1 reverse. The design of the main auxiliary box full synchronizer, synchronizer friction cone using high performance non-metallic materials, light and flexible when hanging. The main and auxiliary box are twin countershaft transmission, main spindle and spindle gear box floating. Using double H control, can be single, double lever control or left, right and two-way control, reliable and portable. The way of taking the power is varied, which can be assembled with the full power of the front full power, the side force, the bottom and the rear force. Short axial dimension, light weight, large bearing capacity, reliable use, convenient maintenance. Applicable models the series transmission used in the input torque to 1000Nm highway truck, since the truck, off-road vehicle, tractor, luxury buses, truck crane, mine car, heavy fire engines and railcar etc..