[TITLE: THE AIR BRAKES' AIR COMPRESSOR | AIR BRAKE SMART\
Hi there smart drivers, Rick with Smart Drive Test talking to you today about the compressor on
an air brake equipped vehicle. The only difference between a compressor on an air brake
equipped vehicle and one that you would find in a garage or shop is that the one
in the air brake equipped vehicle runs the entire time that the motor is running.
And we use the governor to control the compressor on an air brake equipped
vehicle. Today we're going to talk about the compressor, one of the main components
or one of the basic components in an air brake equipped vehicle. We'll be right back to
talk about that.
[OPENING CREDITS & MUSIC]
HI there smart drivers, Rick with Smart Drive Test talking today about the compressor on an
air brake equipped vehicle. In this day in age, all compressors on an air brake
equipped vehicle are bolted right to the side of the engine - they are gear driven.
Now, in all the manuals it will say that some of them are belt driven. They haven't
been belt driven since the nineteen seventies - almost 45 years; however, if
they are belt driven and you do have to check belt as part of the pre-trip
inspection on your unit; halfway between the two pulleys, push down on the belt. If
it goes more than its own width, the belt probably needs to be adjusted and
tightened up. So that's the way you check the tension on belts. And in the rare
case that the compressor might be belt driven. Compressors on air brake systems
are truly parasitic. They take power from the motor to be operated. They use the
engine's lubricating system to be lubricated and cooled. As well, they use
the engine's intake system to filter air into the system and compress it into the
air brake system - air tanks and whatnot. And in some rare cases, they use the
engine's cooling system as well to cool the compressor. In most instances, however
they're just air cooled. There's just fins on the side of the compressor and they
are cooled. So the air compressor on an air brake equipped vehicle is truly
parasitic. It uses everything from the engine to do what it needs to do. The
internal workings of an air compressor on an air brake equipped vehicle is very
similar to an internal combustion engine. There's a piston inside of the
compressor that's on a crankshaft. The crankshaft is turned by the power from the
engine. The piston goes down, creates a vacuum. The intake valve opens and it
sucks air in. It's very much like a plunger in a syringe: you pull it down, it
creates a vacuum and sucks liquid into the needle. An air compressor does the
same. The piston goes down
creates vacuum and sucks air into the piston chamber, the intake valve closes,
the exhaust port opens up, the piston comes back up on its compression stroke
and pushes air into the system. It's that simple.
We compress the air basic—principle of science—when you increase the pressure,
you increase the temperature—the air coming out of the air compressor is 200°C or
approximately 400° F. The air is pushed into the wet tank on the
older air brake systems, where it cools. Cold air doesn't hold as much liquid as hot
air, therefore the water inside the air cools & liquefies, and is collected in the
bottom of the wet tank. Thus we have a drain on the tank and any question on any air
brake system will say how often do you drain tanks? Daily, every day because the
hot air cools, liquid condenses in the wet tank, and the tank has to be drained.
On newer systems— ADIS systems—that don't have a wet tank. ADIS stands for air
dryer integrated system. It's just an air dryer and the air dryer is really good at
purging out that liquidand any other sludge that might be created by the
compressor and whatnot. Compressors, as I mentioned, have an internal piston,
depending on the size of the piston and the requirements of the air brake system,
they can be one to four cylinders. Keep in mind that these larger vehicles—buses
and trucks and whatnot—don't just use the air from the air compressor for the
air brakes. It also uses it for the air ride suspension, the air cab, air ride seats,
air locks, and those types of things. In the old days, we used to have air
windshield wipers, but the engineers kinda listened to the truck drivers because I'll tell you right now,
I've sat in a few trucks with air windshield wipers. There is nothing worse after eight hours.
[AIR WINDSHIELD SOUND & HAND MOVEMENT] They never really worked very well! So we've gone to electric windshield wipers.
They're not air anymore.
The other part that you need to do as part of your pre trip and your air brake
pre trip inspection is you need to do a build-up test - a compressor test. The
compressor test in most provinces in Canada is fifty pounds per square inch
to 90 pounds per square inch at a high idle within three minutes. A couple of
provinces—Newfoundland and Nunavut— are five minutes.
50 to 90 psi within three minutes. Quebec doesn't have one - doesn't have a compressor test,
which is odd. And Ontario is 85 psi to 100 pounds per square inch at a high idle
within two minutes. I'll put a link down in the comment box here for the
different requirements for a compressor test for the different provinces in Canada.
In the United States, just know you got to do a compressor test. Look up whatever
State you're in - it's very easy to find out what that compressor test is.
In conclusion, compressor...bolted right on the side of the engine. It runs the
entire time that the engine is running. The governor controls the compressor and
I'll put a card here for the video on the governor rather. The
governor controls the compressor: puts it into the "load phase", the "unload phase";
"cut-in" or "cut-out" in Ontario and other jurisdictions. The compressor is truly
parasitic. It takes power from the engine, uses the engine's lubricating system, the
air intake, and in some cases the air cooling system. As well, the lubrication
system. And the fins on the outside - most of them are air cooled. The internal workings
of a compressor is very similar to an internal combustion engine. The intake stroke
and a compression stroke. It sucks air in and compresses it & pushes it into the wet
tank or into the secondary and primary tanks on a ADIS system— air dryer integrated
system. All commercial drivers, as part of their license test, as part of ensuring
the safe operation of the vehicle, must do a compressor test. The compressor test is a
set amount of time, it must build a set volume of air - usually 50 to 90 psi in most
provinces within three minutes at high idle. Question for my smart drivers: have
you ever had a compressor fail on an air brake equipped vehicle. Leave a comment
down in the comment section. If you like the video, subscribe, share, leave a
comment. All of that helps us out. If you like what you saw here,
head over to my website - lots of information about air brakes on my
website Smart Drive test dot com. As well, lots of questions for practicing
for your air brake test that you have to take in all provinces if you're getting
a commercial license. Whether that's a truck or a bus. I'll leave a card here
for a link to my website.
Head over there.. practice. Remember the practice driving test questions help you
to learn a skill about taking multiple choice questions for the purposes of
passing a learners test. And for Ontario and other provinces, every five years
when you renew your license you have to take an air brake theory test. So head over
there to practice driving test questions related to air brakes - be successful on
your theory test. I'm Rick with Smart Drive Test: remember, pick the best answer, not
necessarily the right answer!
Have a great day. Bye now!
[CLOSING CREDITS & MUSIC]