Abstract: Theoretical analysis and experiments are made on static and dynamic characteristics of diagraph spring pneumatic brake valve that are one of the main control components for tractor-trailer brake system. The optimization of static and dynamic characteristic parameters of brake valve is obtained by its interior parameters that are changed properly. The brake properties for vehicles pneumatic brake system are increased. The results show static characteristics of diagraph spring pneumatic brake valve is not only affected by the geometric dimensions, equilibrium spring stiffness, input pressure and stroke, but also by machining, assembling and adjustment as well, that the dynamic characteristics of diagraph spring pneumatic brake valve is not only affected by equilibrium spring stiffness, but also by intake valve inner diameter and valve seat hardness.

Key words: Dynamic characteristics, Pneumatic brake system, Pneumatic brake valve, Static characteristics, Tractor-trailer, handling performance, ride performance, physical model coupled with mechanical and hydraulic systems, the design and optimization of the parameters, Hydraulic interconnected suspension