Including engine, torque converter, gearbox, front and rear drive axle, referred to as the four major parts 1. Engine 2. There are three pumps on the torque converter, working pump (supply lift, tip bucket pressure oil) steering pump (supply steering pressure oil) Variable speed pump is also called walking pump (for strain moment, transmission pressure oil), some models of steering pump is also equipped with pilot pump (supply control valve pilot pressure oil) 3... Working hydraulic oil circuit, hydraulic tank, working pump, multiway valve, lifting cylinder and tipping bucket cylinder 4. Traveling oil circuit: transmission oil sump oil, traveling pump, one way torque converter, one way gear valve, transmission clutch 5. Drive: Drive shaft, main differential, wheel reducer 6. Steering oil: oil tank, steering pump, steady flow valve (or priority valve) steering gear, steering cylinder 7. There are two kinds of transmission: one (planetary) and two (fixed shaft)