Relay Valve (Quick-Connect Type)
This component is typically installed in the air brake system piping of commercial vehicles to accelerate brake response time. The part number is WG9000360506.

1. Basic Part Information

• Part Name: Relay Valve (also known as acceleration valve)

• Connection Type: Quick-connect. The image shows blue quick-connect collets. This design requires no thread tightening, offers convenient connection/disconnection, good sealing, and includes anti-misassembly features.

• Appearance Features:

  • Main Body: Compact structure made of silver die-cast aluminum alloy.

  • Top Structure: Features an adjusting screw hole and an electrical connection port.

  • Side Ports: Includes an inlet port, outlet port(s), and a control port (typically marked with a yellow identification ring).

  • Bottom View: Shows the quick-connect bases for inlet and outlet pipes, with a larger adjusting nut in the center.

2. Applicable Models & Installation Position

• Applicable Models: Mainly suitable for the Sinotruk HOWO full series heavy-duty trucks (e.g., T7H, A7, TX, NX, etc.), SITRAK, HOHAN, and other models.

• Installation Position: Typically installed in the middle/rear sections of the chassis brake lines, on trailer brake lines, or at the end of long piping runs — located close to the brake chambers.

3. Main Functions & Role

• Reducing Brake Response Time (Core Function): In conventional air brake systems, compressed air travels from the air reservoir through the brake foot valve and then to the brake chambers. This long path results in slow charging. The relay valve's function is that when the brake is applied, high-pressure air from the reservoir is sent directly and quickly into the brake chambers — bypassing the long intermediate piping — achieving near-instant braking and significantly improving braking efficiency.

• Differential Relay Function: Some relay valves include a differential function that coordinates air pressure transition between the service brake and the parking brake (spring brake), preventing overlapping forces when both systems are actuated simultaneously — protecting brake components from damage.

• Pressure Regulation & Holding: Helps the brake chambers exhaust quickly when the brake is released, and maintains stable system pressure to a certain degree.