[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]