The Role of Relay Valves in Semi-Truck Air Brake Systems

The air brake system plays a critical role in ensuring the safety of semi-truck drivers and other drivers on the road. It is a complex system that requires constant maintenance to run smoothly. And of all the parts that make up this system, the relay valve is perhaps the most crucial. Learn more about the role of relay valves in semi-truck air brake systems, and why keeping it in good working condition is essential.

What Is a Relay Valve?

A relay valve is a type of valve used in air brake systems to control compressed air flow. You can typically find it on the brake chamber, and it is responsible for directing air pressure to the brake chamber’s diaphragm to actuate the brake. The relay valve also balances the air pressure between the front and rear brakes.

Role in the Air Brake System

The relay valve acts as a switch that controls airflow to the brakes in the air brake system. The brake valve transmits air pressure to the relay valve when the driver steps on the brake pedal. The relay valve then opens, allowing the air pressure to flow to the brake chamber, which activates the brakes.

The relay valve also plays a crucial role in the brake system’s balance by equalizing air pressure between the front and rear brakes. This balance is important because unequal pressure can cause the truck to skid or jackknife during braking, which can be dangerous for the driver and other road users.

Maintaining air pressure in the brake system is another crucial relay valve function. The relay valve releases the air pressure from the brake chamber back into the system when you release your semi-truck’s brakes, allowing them to reset. This process ensures that the brakes are ready to be used again when the driver needs to stop the vehicle.

Relay Valve Maintenance

It is essential to keep the relay valve in good working condition. Faulty relay valves can cause the brakes to fail, leading to accidents. Some signs of a bad relay valve include brakes that are slow to engage, poor brake response, and uneven brake wear. Regular maintenance and inspection of the air brake system, including the relay valve, are crucial for the safety of the driver and others on the road.

The role of relay valves in semi-truck air brake systems is important. It balances air pressure between the front and rear brakes, maintains air pressure in the brake system, and controls the compressed airflow to the brakes.

Turn to Van Horn Truck Parts if you need any semi-truck air valves, including pressure protection valves. We carry quality truck parts to ensure your tractor-trailer runs smoothly.