Air Brakes

quick links

An Introduction to Air Brakes

An introduction to the basics of an air braking system as found on trucks and buses.

Air brakes are most commonly found on large and commercial vehicles, where even a power boosted hydraulic brake system would not be able to produce the braking force required to stop the vehicle.

We have an endless supply of air and by storing it and directing it through valves to pistons, we can use the compressed air to exert the braing force.

By using actautors with relatively large surface area pistons, the compressed air can exert a substantial force to the actuating levers.

ABS air brake valve.jpg

Air brake Relays - How they work

A full explanation of the Air Brake Relay, its purpose and how it works.

This video takes us one step further from our "Introduction to Air Brakes" Video and looks into the Relay, which is a device used to speed up the application and release of the brakes, minimising brake lag.

Without a relay, there would be a massive delay in between the moment that the driver applies the brakes and the moment the brakes are actually applied. This delay would be unacceptable and even dangerous. The relay is there to minimise this delay and speed up the application and release of the brakes.


Air brake Relays - Movements and States of Operation

A cut down version of the "Air Brake Relays - How they work" video, concentrating on the movements and the states of operation of the valve.

This video is not narrated and only shows the relay valve itself operating.


Introduction to Spring Brake Actuators

A look at spring brake actuators (SBA) on trucks and buses.



The electronic brake system for off-road operation improves handling in difficult terrain. Besides the paver brake, the hill holder and ASR functions for simplified moving-off as well as ABS for off-road operation for braking on loose surfaces and the turning brake are described here.