This transmission gearbox assembly is the complete power shifting component for SHACMAN heavy-duty trucks. It receives engine torque and changes torque and speed through internal gear sets to meet different driving requirements of climbing, heavy-load transportation and high-speed cruising. The gearbox housing is made of high-strength cast aluminum alloy. Internal gears and shafts are forged from high-quality alloy steel and processed by precision grinding and heat treatment, featuring high rigidity, strong load capacity and wear resistance. The whole assembly undergoes bench running-in test, noise inspection and leakage test before delivery. It realizes reliable gear shifting and stable power output, and can adapt to long-distance heavy haul, mountainous roads and complex working conditions. We maintain sufficient inventory and stable bulk supply for repair workshops, fleet operators, auto spare parts dealers and global cross-border export customers.