The design of hydraulic transmission gear-box is used for forklifts, hydraulic change moment devices and forward and backward stalls two stalls of the driving force for gear gearboxes a hydraulic transmission gear-box. In accordance with the design of the demands of a driver 60 tons of hydraulic power transmission gearboxes design process. hydraulic transmission gear-box mainly by gearboxes, hydraulic change moment, pump total and tone down valve and relief valves components, control valves components, clutch and hydraulic control components. So that the hydraulic torque converter transmission with hydraulic transmission output gear automatic adaptation to changes in external load with corresponding changes in its output torque and speed, but also requires the ability to absorb and remove from the engine and the outer load on the transmission of shock and vibration The approach requires control gear used in simple, easy, smooth start, more to reduce the labor intensity of operators.