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Basic CDL Air Brake Components

Basic CDL Air Brake Components


[TITLE: BASIC AIR BRAKE COMPONENTS | AIR BRAKE SMART] Hi there smart drivers, Rick with Smart Drive talking to you today about the fundamental component of the air brake system. The
fundamental components consists of the compressor, the governor, air tanks,
airlines, the brake pedal, and the foundation brakes. And the foundation
brake can be one of four types. We’ll be right back to talk about that. [OPENING CREDITS & MUSIC] Hi there, Rick talking to you today about the fundamental component of an air brake system. The fundamental components are: compressor, governor, airlines, air tanks, brake pedal, and the foundation brakes. These are the
fundamental components and by no means in this day in age are these the only
components. We’ll start with this and then as we go through the course we’ll build on
the different valves and components of an air brake system. And finally, by the
end of the course you’ll have an understanding of why in this day and age
air brakes are bulletproof. This here, you can see is the fundamentals of a basic air
brake system. This is obviously not what an air brake system looks like, but just
to give you some idea of the fundamentals of the air brake system. You can see here, the first part that we need is—we need somehow to compress the air in the system—we have an air compressor. The air compressor on air brake equipped
vehicle is exactly the same as what you would find in a garage. The only
difference between a compressor in a garage, and a compressor on an air brake system, is that the compressor on the air brake system – it runs all the time that
the motor is on. So we need some way to control the amount of air that we put in
the system. Because if we just keeping pumping air into the system, that
compressor is capable of pumping up to 500 pounds per square inch. We don’t need 500 pounds per square inch; we only need a maximum 135 pounds per square inch. So we have the governor – the governor controls the compressor. Think of the
governor on a compressor like a thermostat on a furnace. The temperature in the house gets down to a minimum, the thermostat turns the furnace on; the
temperature goes back up to a maximum the thermostat turns the furnace off. A
governor does exactly the same thing. The system goes down to a minimum air
pressure, it puts the compressor back into the load phase and loads the system.
In Ontario and some other places they call it be “cut in;” system goes back up to
maximum pressure—we know that it’s a maximum pressure because the needles—the air gauge needle stop climbing and the system is between 105 and 135 pounds per square inch—at maximum pressure, the air that the compressor is generating is simply pumped into the
atmosphere. We call it the “cut out” phase or the “unload phase.” So the governor
controls the compressor. We also have to have air tanks to store the air. This is
one of the first fail-safe systems in any air brake equipped vehicle – air tanks. All of the air tanks on these
air brake equipped vehicles are capable of holding 10 to 12 full brake
applications. That volume of air – so if the compressor falls off the side of a
vehicle for whatever reason—which it may or may not—there’s enough air stored in
those air tanks for ten to twelve full brake applications. On the air tank we need
some way to prevent it from exploding or imploding – all tanks used in commercial
uses – industrial uses – all have some sort of safety valve on them. This tank here, you can see the safety valve here. The safety valve is designed on an air brake system to evacuate air from the system at a hundred and fifty pounds per square inch.
You as the driver will know that the safety valve is evacuating air from the
system because they sound like a machine gun. [MACHINE GUN SOUND] If you hear that sound, you can authoritatively take the vehicle to your mechanic and say, “there’s something wrong with the governor or the compressor!” Most likely the governor. As
well, on the bottom of the tank here, you can see a drain valve. All tanks have to
have drain valves. Most of them now are automatic or they have some sort of pull
cord on them. The reason they have to have drain valves because when you compress the air
you heat it up – it goes into the tanks. It cools and the water liquefies inside the
tank because of the cooling process. Think of it like a drink in the
summer time with ice cubes in it: the hot air comes into contact with the
cold glass on the outside. The vapor… the liquid vapour inside the hot air cools
and forms water droplets on the outside your glass. That’s exactly what happens
inside of an air tank. Also on the system we can see that we need airlines. The
airlines harness and direct the air pressure into the system. As well
we have a brake pedal. You can see the brake pedal here. Just push down on it – it’s essentially a valve. Brakes
on, brakes off. It’s for the service brakes. There are two kinds of brakes on a big truck that’s equipped with air brakes. 1) The service brakes and the 2) spring brakes.
The spring brakes are primarily used for parking and in the event of an air
loss, also for emergency brakes. But for this fundamental system these are the
service brakes. The brakes that you use going up and down the road after you release the parking brakes. The brake pedal is also called the foot valve or the treadle
valve, but for terms of simplicity we just call it the brake pedal. The brake pedal
directs air out to the foundation brakes and the foundation brakes consist of the
brake chamber, the pushrod, the slack adjuster, the ‘S’ cam, and the drum brakes.
In this case, as you can see here in the diagram, these are drum brakes. There are four types of foundation brakes: 1) drum brakes, 2) disc brakes, 3) air-over-hydraulic brakes, and to a certain extent wedge brakes. Air-over-hydraulic brakes and
wedge brakes – you’re not going to find them in this day and age. These pretty much became obsolete when
gasoline engines were replaced by diesel engines. Gasoline engines created vacuum, which made air-over-hydraulic brakes plausible because they could use the
vacuum from gasoline engine to power the master cylinder. Once diesel engines took
over, they no longer created vaccum and it was no longer feasible to have air-
over-hydraulics. So it was just the air-over- hydraulic became obsolete. And they went to a completely air brake system. Wedge brakes: in the twenty years that I’ve
been teaching air brakes, I have only ever seen wedge brakes once, and that was on a trailer on the [Vancouver] island and it was kind of a novelty to take the students out
and show them wedge brakes. The question on the test for wedge brakes is: they may
have one or two brake chambers. That’s the question on the test. As well, to identify a wedge
brake, the brake chamber and the push rod will be facing into the brake assembly,
as opposed to at a 90° degree angle as they are on drum brakes brakes. So the brake pedal directs air out to the foundation brakes. And as you can see in the image here it is a drum
brake and that is the most common on large commercial vehicles at this
juncture. Disc brakes are beginning to make inroads into the industry – not quite
there yet. We’ll talk to you about the review questions here. The review questions -shut the video off, answer the review questions and then
turn the video back on and I’ll go over the review questions with you. First
question: what are the six fundamental components of an air brake system? The
six fundamental components are 1) compressor, 2) governor, 3) air tanks, 4) airlines, 5) brake pedal, 6) foundation brakes. The foundation brakes can be one of four
types: 1) drum brakes, 2) disc brakes, 3) air-over- hydraulic, and 4) wedge brakes. Second
question: what is the purpose of the governor? The governor controls the
compressor. The compressor runs the entire time that the motor is running, so we
need some way to control the compressor, and the way that we do that is is that we
unload it into the atmosphere or load it into the system and British Columbia and
other provinces we call it the load phase – pumps air into the system, or the
unload phase, where it pumps air into the atmosphere. In Ontario and other
jurisdictions it’s the cut-in or cut-out. So it cuts-in – pumps air into the system or cut-out and pumps air into the atmosphere. Third question: how are the air tanks the first fail-safe in an air brake system?
The air tanks are the first fail-safe in the air brake system because they hold
enough air for ten to twelve full brake applications if they are not replenished.
So in other words, if the compressor falls off the side of the motor for
whatever reason, there’s enough air in the air tanks to make ten to twelve full
brake applications. Question, what is the purpose of the drain valve? The purpose of the drain valve is to drain water from the air tank so they don’t freeze up and
cause damage to the air brake components. And other sludge and whatnot that is
discharged from the compressor and just some of the dirt and sludge and what not.
Question on the test: how often do you drain wet tanks? The answer to the question is:
daily – every day. you drain the tanks on an air brake
system. And the last question: what is the sound of the safety valve when it blows off at a hundred and fifty pounds per square inch. The sound is a machine gun. [MACHINE GUN SOUND] That is
the sound of the safety valve blowing off excess air in the system because we
have too much air you could cause damage to the system and potentially to
yourself or other people around the vehicle. So all tanks used in industry
and for commercial uses have a safety valve that blows off excess air or
vacuum prevents the tank from either exploding or imploding is the purpose of
the safety valve. Question for my smart drivers: are you taking an air brake course? Is there anything you need help with in terms of your air brakes. Leave a comment down inthe comment section. I’ll be more than happy to help you. If you want to do some
practice test for your air brake course, whatever that may be – whether you’re in
the United States and Canada – go over to my website Smart Drive Test. I’ll leave a
link here. You can find some practice driving test questions over there for
less than $10. Practice driving test questions all provide feedback. They’re really great questions. I’ve been an air brake instructor for twenty years. I’ve read
most of the manuals in Canada and the United States. So the questions are
informative and will help you to prepare for the theory test that you have to
take for air brakes. Thanks very much for watching. I’m Rick with Smart Drive Test. If you like the video, share, subscribe, leave a comment down in the comment section. All that helps us out. Thanks very much for watching. Remember, pick the best answer, not necessarily the right answer. Have a great day! Bye now. [CLOSING CREDITS & MUSIC]


Reader Comments

  1. Hey rick excellent video im having an issue with my brakes, tanks will build 120 psi, but once i push in my parking brake the pressure declines rapidly out of a new relay valve i just put on…now granted i hadn't drained my tanks all this winter…could it be the build up in my tanks

  2. Anyone know if pumping the brakes on an air brake system to release the air affects the lifetime of the relay valves throughout the system?

  3. Yeah, I like the sound of a machine gun, otherwise, your pictorial is limited. You need more pictorial about the other relationship among the parts.

  4. Terms up front great
    Visual great
    Organization great
    100 psi to 125 psi. (105 – 135 ?)
    Govenor Over 150 psi safty valve
    10 to 12 x full breaking
    Capable of 500 psi
    Auto or pull to release water or oil
    SERVICE break say again
    4 types repeat please

  5. thanks a lot Manย . I read DMV CDL driver,s handbook didn't learn a damn thing . I think this was the best way to learn for new truck drivers.

  6. Here are some of your BFT for ac transit bus 6? #1Pivot point:is center of the rear axle. #2 turning point:center of the front axle.#3 reference point: point the objet around which you need to clear with the pivot when making a turn.#4 rear overhang:The part of the bus that extends from the pivot point to the tailing edge of the rear bumper#5 front over hang: The part of the bus that extends from the leading edge of the front tires to the leading edge of the front bumper or the bike rack.#6 cheat:the rear tires track inside the path of the front tires in turn and curves. This is for ac transit test you need to shade in on the test the over hang . Study just like this

  7. I'm in the US, not Canada, but wondering if I'm applying for a class B CDL but will NOT be driving a vehicle with air brakes, will I still be tested on air brakes?

  8. Dam………Mr Rick, you should be teaching Chemistry. You definitely find the easy and simply way to teach!
    Thank you again!

  9. Hi this is Lyn from Vancouver Island I have failed my written test 3 times I get so confused which valve does what can you tutor me please I can be reached at [email protected] thank you I want to pass and now I feel over burden with studying and brain fog

  10. This combined with my Manitoba manual provides much needed clarity, good to know how reliable air brake systems are!

  11. The fundamentals are why I came here, however, nothing is obvious to me at this stage in my desire to learn. THANKS for the info.

  12. I have a FRR ISUZU I have two air tanks one infornt and one on the back i don't have no air pressure on the front and a little in the back but nothing in the front what can it be

  13. I'm having to take an air brake test to get a class b cdl. I wanted to thank you for explaining this. Its helped a lot to see all the components rather than just read about them. Do you have a more in depth video about the brake components where you actually show them from a real vehicle?

  14. Hey Rick August,
    Thank you very much for the amazing knowledge you share with masses, I am subscribed to your youtube channel and amazed at the in depth knowledge you possess on the subjects you produce videos. I am a pro driver and would like to request you to Please produce an in-depth video on engine / Jake brake system, about its components, kinds, how they work and all the science related to Jake brakes. I am pretty sure that a video on Jake brakes will be a great help to all the pro drivers out there. Cheers.

  15. It seems that trucking is one of those careers which requires a fairly decent understanding of mechanics in addition to driving.

  16. PERFECT! At first, I dreaded the monotoned voice, but soon realized you must have used it by design because I could focus on the content. Good job!

  17. Hello! I just found your channel and how amazing it is, thank you for this free class….I am currently working on my 1985 Chevy k20 and the person who gave it to me said I needed to remove air from the pipes and bleeding the system would do it… but just yesterday I found out that I might have a air brake system installed on it because I do see a black k-h box under the dash… I never used this system before and my brakes are not braking properly it is braking when I pump once very hard… and it is extremely dangerous to drive when the traffic is intense… how can I get started? I donโ€™t hear the governor noise like a gun machine like you say… I attempt to bleed the fluid and the one person procedure was not working for me… and I broke the bleeding valve on the front passenger side too rust to come out… I am currently studying mechanical and I work in the it industries everything I know is very basic but I love to troubleshoot car and I dive into it if you give me some starting directions…. I want to learn the air brake systems before I kill myself driving my old truck… buddy sorry for the long message but I will keep my eye on your channel to learn more!

  18. Is the compress a belt driven or is it gear driven that is a question that they are going to ask on the test I don't know which one it is so I can tell them

  19. So helpful to see a diagram of the system. It was hard to study when I couldn't apply what I was learning in a practical way. thanks for the explanation and the questions after the explanation.

  20. Thanks, Rick. I need to get a CDL to operate some equipment at my job and reading all this stuff in the book without ever having seen it wasn't getting me very far. Your diagram and explanations helped a ton!

  21. Thank you for the videos Rick, your passion and love for what you do helped me pass the air brake CDL exam. No joke Sir, I literally thought of your videos while answering the questions. If you have any content on Hazardous Material let me know. I took all the other endorsements yesterday except for the Hazardous exam. Thanks again for your time.

  22. I'm in Nova Scotia and require to pass the written test in order to apply to the college. Thank you for your videos.

  23. YOUR AVERAGE TRUCK DRIVER DOES NOT DRAIN THE TANKS DAILY….
    PROOF….
    YOU DONT SEE THE SPOTS ON THE TRUCK STOPS….
    YOU MAY FIND MORE BOTTLES WITH URINE ON THE GROUND…
    with respect for the industry.

  24. Thank you. I'm a 38 year young woman, who decided to get my cdl. I was told the test is hard. Wish me luck

  25. You can not set your brakes if you are a driver driver has to call a SE to come out on the side of the road to set them 2 hundred dollars

  26. Need helping with passing cdl manual is dry and looking for video that can simplifying CDL Manual . love your video

  27. Simple question — why in europe we have a single lever for parking brake yet in the states you have a push/pull yellow button —- why the difference ?

  28. Great video! Just bought a 40 ft diesel pusher RV and going to drive this thing from TO to Vancouver Island. Never had an RV before, already overwhelmed by just looking at it, so will just start with the air brake license and work my way through the rest. Any tips for road test for DZ license Ontario? I bought the air brake book from your website, need all the knowledge possible to get through the Rockies safely. ๐Ÿ™‚

  29. Hello Rick,
    Iโ€™m working on my class1 lincense in Quebec and just failed my knowledge test. Can you recommend any of your courses that will help me out the next time I take the test(also for air breaks too)?

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