Instructions of H bivavle and relay vavle and hand brake vavle
The double h valve is mainly used for high-low shift and base shift with auxiliary box.
In the braking system of truck, the relay valve plays the role of shortening the reaction time and the pressure establishment time.
The hand brake valve can control the parking brake of the vehicle. When there is a trailer, hand brake valve can also control the control valve of the trailer and release the air in the brake chamber.