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Air Brakes

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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.

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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.

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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.

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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.

Air Brake Quick Release Valve - How it works

QRV's are fitted to an air braking system to speed up the release of air, as it takes longer for air to escape a system than it does to put it in there. The main applications for quick release valves are in the service line to speed up the release of the service brakes, and in the secondary circuit to speed up the application of the park/secondary brakes. With a similar purpose to the air brake relay, the QRV is just there to speed up the release of compressed air from the braking system.

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