20%。Improper shifting of the heavy truck which is installed with a manual 12 speed gear box usually makes the clutch wear and tear. To solve this problem, an auto-shift system was designed through integrated control method, and so were the automatic implements for gear box and clutch. Through interaction with electric controlling engine, the adapted control on the power driveline of the truck was carried out. The vehicle driving tests prove that the auto-shift system can resolve the excessive wear of the clutch, and improve the economical characteristic of fuel by 20%.  