[TITLE: THE GOVERNOR | AIR BRAKES SMART]
Hi there smart drivers, Rick with Smart Drive Test talking to you today about the governor
in an air brake equipped vehicle. The only difference between a compressor in a shop
or a garage and the compressor on an air brake equipped vehicle is that the air compressor runs
the entire time the motor is running. So we need some way to control it. The governor
is the way that we will control the compressor on an air brake equipped vehicle. We're
going to talk to you today about how it does that. We'll be right back with that information.
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Hi there smart drivers, Rick with Smart Drive Test talking to you today about the governor
on the air compressor. As I said in the introduction, the compressor on an air brake equipped vehicle
runs the entire time that the motor is running. And because the compressor is capable of pumping
up to 500 pounds per square inch, we need some way to control it; otherwise the air
that is compressed by that compressor could potentially be dangerous and pose risk to
yourself and other people in and around your vehicle. The governor does this by the load
and unload phase. And essentially what it does - it's kind of like a railway switch,
puts it into a load phase , where it pumps air into the system or puts it into the unload
phase where it pumps air into the atmosphere. You you can kinda think of the relationship
between the governor of compressor kinda like the bossy wife & the lazy husband! The bossy
wife tells the husband to go out and cut the grass. So the compressor goes into the load
phase and starts pumping air into the system. When it's done pumping into the system, we're
at the maximum pressure, which in most air brake systems is 135 pounds per square inch. The wife says,
"okay, you're all done. You can go in." And he goes in and sits on the couch watches
teli, drink beer and belches. That's the relationship between the governor and the compressor, and
think of it like that. Or you can change the sexes too - one or the other.
The governor controls the compressor. It puts it into the load phase the unload phase or
cut-in cut-out, as it's called in Ontario and other jurisdictions. You can find the
video for the compressor here to get more information about the compressor. I'll put
a card up for you there. The other thing about the governor—the other analogy that works
really well—is if you think of the governor like a thermostat on a furnace. When the temperature
in the house goes down to a minimum, the thermostat turns the furnace on. When the temperature goes
back up to a maximum - the thermostat turns the furnace off. A governor works exactly the
same - so the minimum and maximum that the governor works in in an air brake equipped
vehicle is 80 pounds per square inch on the minimum, 135 pounds per square inch on the
maximum. Now most modern air brake systems work within 20 pounds between maximum and
minimum. So therefore if the air brake system works at a maximum of 125 pounds, it's going
to work in a minimum pressure of 105psi. So the governor will return it. The reason we
go to 80psi, is so that—you know—all the old-timers who got their 1956 Pete[erbilt
truck]; they can still drive them; they will still pass the air brake test because the
governor will put the compressor back into the load phase by a minimum of 80 pounds per
square inch. Now as part of your pre-trip inspection for the purposes of a road test
and for the purpose of ensuring your vehicle is safe, you have to test the compressor and
you have to test the governor. The two tests for the governor are: pump down to above 80psi,
throttle up a little bit and watch the needles climb. If the needles are climbing, you know
that the governor has put the compressor back into the load phase. The way that you know
that the governor has put the compressor in the unload phase is that you pump up the maximum
pressure. At maximum pressure, the air dryer is going to purge. You're not going to hear
anything else. You're not going to hear the compressor, you're not going to hear the governor.
The governor's kind of like Arnie - you know, Arnie was the governor of California. He's gonna
kill you all silent like! The governor does the same thing; you're not going to hear it!
the air dryer. At maximum pressure, the air dryer will purge. It is confirmed by looking
at the needles: the needles have stopped climbing. Like a glass of water - when you fill it up
and stop putting water in it, the water level stops stops rising. The needles have stopped
climbing, therefore, I know that the governor has put the compressor into the unload phase
at maximum pressure between 105psi and 135psi in most provinces in Canada. So that's the
governor test that you have to do as part of your pre-trip inspection for the purposes
of a road test and to ensure your vehicle is safe.
In conclusion, the compressor runs
the entire time that the motor is running on an air brake equipped vehicle therefore
we need some way to control it. We control it with the governor. The governor puts the
compressor into the load phase where pumps air into the system or the unload phase where
it pumps air into the atmosphere. In Ontario and other jurisdictions, they call it the
cut-in phase or the cut-out phase. Think of it a little bit like a railway switch, right,
it's either on the main track or it's in the side track and when the compressor is in the
unload phase it just kind of hangs out [COMPRESSOR HANGING OUT SOUND], cools off and doesn't
really do too much. Until it's put back into the load phase or the cut-in phase and then
it pumps air back into the system. Think of the governor like a thermostat on a furnace:
when it gets to the minimum, it turns it on, when it gets to maximum, it turns if off.
A governor works exactly the same. As part of your pre-trip inspection, you have to test
the governor. You have to test the minimum setting, which is it has to return the compressor
to the load phase by a minimum of 80 pounds per square inch. And it has to put it in the
unload phase at maximum pressure between 105psi and 135psi in British Columbia and other provinces.
In Ontario, its between 80psi and 135psi. But most of the time it'll be around 125psi,
so you know it's a maximum pressure: the air dryer purges, you look at the needles - the
needles have stopped climbing, and the system is between 80 and 135 pounds per square inch
in Ontario. That's the test for the governor and the criteria for the governor. Question
for my smart drivers: have you ever had a governor fail and causing it to build up where
the safety valve has engaged? The safety valve sounds like a machine gun! [MACHINE GUN SOUND].
So have you ever had a governor fail on an air brake equipped vehicle? Leave a comment
down in the comment section. All those stories are great; all those stories help out the
new drivers we're trying to help out here on the channel. If you like the video, subscribe,
share, leave a comment down in the comments section. All of that helps us out. If you
like what you saw here, head over to my website - lots of practice driving test questions
for air brakes. In Ontario and other provinces, you have to take a theory test on air brakes
every 5 years when you renew your license. Lots of practice driving test questions. They
teach you how to take the multiple choice driving test questions and they teach you
about all of the numbers—specific numbers—you need to know to do the air brake pre-trip
test for the purposes of the theory test that you need to take at the MTO [Ministry of Transportation
of Ontario]. I'm Rick with Smart Drive Test. Thanks very much for watching. Remember, pick
the best answer, not necessarily the right answer. Have a great day, bye now.
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