WorksheetsCDL MN air brakes
Total questions: 37
Worksheet time: 19mins
The parking or emergency break on a heavy vehicle can only be held in positibn by something that cannot leak away like
hydrolic pressure
spring pressure
air pressure
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IF the air compressor should develop a leak, what keeps the air in the tank?
The one way check valve
the emergency relay valve
the tractor protection valve
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THe modulating control valve allows you to control the:
spring breaks
amount of pressure in the break system
front breaks
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When you put the brakes on by pushing down on the break pedal:
compressed air is let go out to the system
Air pressure is applied to the brake pads
The air pressure is reduced to the brake pads
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Which of these is the most important thing to remembner about emergency braking.
Never do it without downshifting first
If the wheels are skidding, you cannot control the vehicle
Disconnecting the steering axle brakes will help keep vehicle in a straight line during emergency breaking.
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To correct a drive wheel braking skid, you should:
Increase braking, turn quickly and counter steer.
Stop breaking, turn quickly and counter steer
increase braking
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The driver must be able to see a warning before pressure in the service air tanks falls below ________ psi
60
50
80
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In air brake vehicles, the air brake should be used:
Any time the vehicle is parked
To hold your speed when you are going down hill
as little as possible
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To check the brake slack adjusters on S-cam brakes you should park on:
Park on level ground and drain off air pressure before adjusting
Stop on level ground and apply the parking brakes
Park on level ground, chock the wheels and release the parking brakes
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In ideal conditions a truck or bus with an air brake going at 55 mph would require stopping distance of how many feet?
less than 100
more than 300
100-200 ft
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Excessive use of the service brakes results in the overheating which can lead to:
Expansion of the brake drums
increased contact between the brake drums and linings
Proper adjustment of the S-cams
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What do air brakes use to make the brakes work?
compressed air
compressed gas
compressed oil
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Air braking takes more time than hydrolic braking because air:
Air brakes use different brake drums
Takes more time to flow through the lines than hydraulic fluid
Brakes require heavier return springs
-
The service brake applies and releases
The parking brake when you use the parking brake control
In the event of an emergency
The brake when you use the brake pedal during normal driving
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The air supply pressure gauge shows how much pressure
Is going to the brake chambers
You have used in this trip
is in the air tanks
-
To test the air leakage brake you should
charge the air system and leave the engine running
turn off the engine and release the parking brake
leave the engine running and release the parking brake
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If the truck has a properly functioning dual air system and minumum size air tanks. The air pressure should build from 85-100 psi within ________ seconds.
60
20
45
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To check the brake slack adjusters on S-cam you should park on:
Park on level ground and drain off air pressure before adjusting
Stop of level ground and apply the parking brake
Park on level ground, chock the wheels and release the parking brake
-
If the air compressor should develop a leak, what keeps the air in the tanks?
The one way check valve
The emergency relay valve
The tractor protection valve
-
The most common type of foundation brake found on heavy vehicles in the:
Disc drum
Wedge drum
S-cam drum
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It is not safe to drive a vehicle that has brake drums (or discs) with cracks or that are thinner than the manufacturer's specs, generally with will be ____ an inch.
1/3
1/4
1/2
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During normal driving, spring brakes are usually held back by
springs
bolts and braces
air pressure
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Modern air brake system are 3 different systems combined together. They are service, parking and ______ brakes.
foot
S-cam
emergency
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The air brake system for a straight truck or bus should not leak at a rate of more than ____-psi per minute with the engine off and the brakes released.
1
2
3
-
Excessive heat in the brakes can cause the brakes to
fade or fail
modulating control valve to wear out
brake lines to plug
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Which of these not a proper tine to apply the parking brakes
If you are going to use the parking brakes you need you make sure that they will hold the vehicle
If your brakes are very hot
To use parking brakes if you park for less thatn 1 hour
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What is a dual air brake system?
One operates the front brakes, the other the back
one for daytime, the other for night driving
One for each side of the vehicle
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The stop light switch
turns on the brake lights to warn drivers behind you
tells you when the air brake system is low on air pressure
tells you when you need to use your emergency brakes
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The air compressor stop pumping air at what psi
150
125
100
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The total stopping distance for air brakes is longer than that for hydraulic brakes due to ______ distance
reaction distance
Brake lag
Effective braking
How can you test the low pressure warning signal
While the engine is running, step off and on the brake pedal
Shut off the engine and see fi the air pressure leaks down
Shut off the engine with enough air pressure, turn of the electrical power and step on and off the brake pedal until the low air pressure warning signal comes on.
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To test the air leakage rate you should:
Turn off the engine and release the parking brake
charge the air system and leave the engine running
leave the engine running and release the parking brake
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The air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than:
2 psi in 45 sec
1 psi in 1 min
3 psi in 1 min
-
The driver must be able to see a low pressure warning which comes on before pressure in the service air tank falls below:
100 psi
60 psi
80 psi
-
The most important thing to do when the air pressure warning comes on is:
Stop and safely park as soon as possible
upshift
downshift
-
The air compressor governor controls:
air pressure applied to the brakes
when air is pumped into the air storage tanks
The speed of the air compressor
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The air brake system for a straight truck or bus should not leak at a rate of more than _______psi per minute with the engine off and the brakes released.
3
1
2
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