Learn About Emergency Brake Valves

Emergency relay valve has two functions: emergency function and relay function
1. Relay function: Port 1 is connected to the red tube, port 4 is connected to the yellow tube, and ports 1-2 are connected to the air reservoir. When the tractor provides a brake pressure signal (the principles of handbrake and foot brake are exactly the same for trailers), the yellow tube Intake air, open the piston inside the valve, the compressed air in the air reservoir enters the valve chamber through ports 1-2, and then enters the brake chamber through port 2, and the vehicle brakes; the tractor releases the pressure signal, the yellow pipe is empty, and the brake The compressed air in the air chamber returns to the valve chamber through port 2, and then is discharged into the atmosphere through port 3, and the vehicle brake is released.
2. Emergency function: When the red pipe connected to port 1 is disconnected (no ventilation), the compressed air in the air reservoir directly enters the valve chamber through port 1-2, and then enters the brake chamber through port 2, and the vehicle brakes
 
Port 1: Air inlet
Port 2: Air outlet
Port 3: Exhaust port
Port 4: Control port
Port 1-2: Connect the air reservoir
All the above functions are completed by the single-chamber air chamber, that is, the diaphragm chamber. The rear chamber of the double-chamber air chamber, that is, the spring chamber, will only work after the compressed air in the brake air chamber leaks, which is called mechanical braking.