Oil pressure characteristic of automatic transmission's shift control unit and clutch failure analysis

This paper researches on oil pressure characreristic in the shift control unit of a heavy vehicle's automatic transmission. The simulation model of its control unit was founded in the ITI-SimulationX software. Through a bench experiment, the correctness and effectiveness of the model has been checked. To solve the early failure problem of the clutch in the road test, optimizing its oil characteristic in the model by adjusting parameters and improving the model structure. The optimization results indicated that two factors, impacts between hydraulic control units when shifting and long time of sliding friction, were the major reasons leading to early failure. Modifying the structure of the AT prototype according to its simulation model, the early failure problem has been solved effectively.