Air Brakes - An Introduction. How it works.

This video gives an introduction and brief look at air braking systems on heavy and commercial vehicles.

You'll see from the animations that all systems have a compressor to supply the air, reservoirs to store the compressed air, controls for the driver to direct the air (foot and hand brake) and actuators and friction brakes to actually carry out the braking.

This video sticks the the fundamental basics of the Air Braking System and doesn't go as far as other system components such as s-cams, relay, quick release and trailer control valves, air dryers and filters, protection valves and other system operations. We'll go into depth with these in further videos.

Camera gear used in this video:

[lanceuppercut]

Oh wow, that is way more intricate than I thought. Been playing American Truck Simulator and dealing with charging the brake system and loosing pressure has brought me here to try to learn the way it works IRL. Thanks for the vid.

[ertren]

As a diesel mechanic for school buses and now going to work for the cities waste managmenet fleet service, vids like these are a breath of fresh air.

[vincentscats]

now that explains the "tsss" sound I hear everytime a truck brakes. Been curious about it since I was a kid.

[coffeejazzdude]

Thank you very much. I have a test on this tomorrow and this has been an awesome study aid.

[edwardgaines]

I start CDL training next week. Thanks for rundown, I hope this all sinks in!

[davidhenderson]

Most people do not understand how air brakes work. They think if you lose the air you lose the brakes. When in fact the opposite is true. You lose the air and the brakes lock up. I have lost count at the number of times I have seen movies where the air is lost and they have a run-a-way with no brakes.

[Maniac]

I am already very familiar with the air braking systems on trains, being a train nut, and while knowing that air brakes on commercial road vehicles must work in a similar manner, I did not know the functional differences. I also did not realize there can be a delay between pressing the brake pedal, and the brakes being applied.

[nick-cjdw]

Thank you so much for this great great video!

[GunawanWidihardjo]

Thank you, this video is very helpful for air brake system analysis

[vasiliymedvedev]

So when you engage, the handbrake air is pumped into a chamber in the brakes, releasing them. When the brake pedal is pressed is the air released from the handbrake chamber? or more air is pumped into an opposite to the handbrake air chamber (working against the handbrake) and engages the brake and then when foot pedal is released the air from this second air chamber is released make the brakes free?

[dsrabelo]

Educational Mechanics, could you please enable adding subtitles to your video? I would like to add a Portuguese version of the subtitle for this great video!
Thanks!

[Michelle_Schu-blacka]

From what I can gather, air brakes work in a sort of opposite way to hydraulic brakes.

In hydraulic brakes, you need fluid to compress the pads against the discs, but in lorries, you're sort of taking air away, allowing the brakes to 'unlock' and compress against the rotor, so if you have no air, the brakes stay 'unlocked'.

Does that sound about right?

[PopCapMusicTrending]

I am just curious why those big vehicles make that air-compressed sound when moving from a complete halt.

[dhxl]

Hmm...Still don't get how the amount of brake torque is regulated? The more you press the brake pedal the more you get air input to the brake chamber. But? But! Let's say we have infinite amount of time and the brake pedal is 1% pressed. Versus. The same conditions but brake pedal is 100% pressed. So will we have the same brake torque at some point with the difference that 100% pressed brake pedal will generate that max brake torque much faster, while 1% pressed pedal will take considerable time to generate that max brake torque?

[mchlrdx]

I have been driving trucks for 15 years(this upcoming april) and I know absolutely everything about the air brake system....but one thing I've never understood is where the hell does the air exaust from the brake chamber?? The high pitch air it from the gap in the slack adjuster??? I'm no rookie but I'm just curious lol

[balakumaran]

Actuators is used for braking speed of rear brake than the front brake when brake is applied, so the heavy vehicle is control the balance by driver

[paragjh]

What is the time lag between application of break and stopping of unloaded truck 16 tyres running 50 km/h?

[jasonsahl]

Not sure where you got all your footage from, but the opening B-roll is definitely from Olathe, KS.

[nightmareinaction]

Is that why I see a lot of semi tire Mark's do they run out of air and brakes engage or what ?

[GuerillaManifesto]

So for the parking brake, you're essentially forcing air into the chamber to compress the discs? And the same for standard braking, you're forcing air to compress the discs? And when you let off the pedal (or release the parking brake) you're letting the air out of the chamber?