CDL PRACTICE TEST - AIR BRAKES
CORRECT 100%
A slacking adjuster probably needs to be adjusted if it moves more then about _______
inch when you pull hard on it. - ANSWER 1
Excessive use of the service brakes result in overheating, which can lead to: -
ANSWER Expansion of the brake drums
Repeatedly pressing and releasing (fanning) the brake pedal may result in: - ANSWER
A loss of brake air pressure
The brake pedal in an air brake system: - ANSWER Controls the air pressure applied to
put on the brakes
You should know that your brakes are fading when: - ANSWER You have to push
harder on the brake pedal to control your speed on a downgrade
Your truck or bus has a dual air break system. If a low air pressure warning comes on
for only one system, what should you do? - ANSWER Stop right away and safely.
Continue only after the system is fixed.
Under ideal conditions, a truck with air brakes going 55 miles per hour would require a
stopping distance of: - ANSWER More than 300 feet
Modern air brake systems combine three different systems. They are the service,
parking, and the _______ brakes. - ANSWER Emergency
Total stopping distance for air brakes is longer than that for hydraulic brakes due to
_____ distance - ANSWER Brake lag
Emergency controlled braking is when when you: - ANSWER Apply the brakes as hard
as you can without locking the wheels.
If you do not have automatic tank drains, how often should you drain the oil and water
from the bottom of compressed air storage air tanks? - ANSWER At the end of each
day of driving
If your vehicle has an alcohol evaporator, every day during cold weather you should: -
ANSWER Check and fill the alcohol level
The most common type of foundation brake found on heavy vehicles is the: - ANSWER
S-cam drum
, The air brake lag distance at 55 miles per hour on dry pavement adds about _____ feet
to your stopping distance - ANSWER 32
The air loss for a straight truck or bus with the engine off and the brakes on should not
be more than: - ANSWER 3 psi in one minute
The air compressor governor controls: - ANSWER When air is pumped into the air
tanks
It is not safe to drive a vehicle that has brake drums (or discs) with cracks that are
longer than _____ the width of the friction area. - ANSWER 1/2
Air braking takes more time than hydraulic braking because air: - ANSWER Takes
more time to flow through the lines than hydraulic fluid
The modulating control valve enables you - ANSWER to put on the spring brakes
gradually.
The S-cam: - ANSWER Forces the brake shoes against the inside of the brake drum.
If your truck's air compressor has its own oil supply, when should you first check the oil
level? - ANSWER Before driving
The supply pressure gauge shows how much pressure: - ANSWER Is in the air tanks
If you must make an emergency stop, you should brake so you: - ANSWER Can steer
and your vehicle stays in a straight line
The brake system that applies and releases the brakes when the driver uses the brake
pedal is the _____ brake system - ANSWER Service
the braking power of the spring brakes: - ANSWER Depends on the service brakes
being in adjustment
To check the free play of manual slack adjusters of S-cam brakes, you should park on: -
ANSWER Level ground, chock the wheels, and release the parking brakes
The driver must be able to see a warning before air pressure in the service air tanks
falls below _____ psi - ANSWER 60
If you are driving down a steep downgrade and you have reached your "safe" speed of
40 mph, you would apply the service brakes until your speed drops to _____ mph -
ANSWER 35
Which of these is NOT a proper time to apply the parking brakes? - ANSWER If the
brakes are very hot (e.g. after coming down a steep grade)
CORRECT 100%
A slacking adjuster probably needs to be adjusted if it moves more then about _______
inch when you pull hard on it. - ANSWER 1
Excessive use of the service brakes result in overheating, which can lead to: -
ANSWER Expansion of the brake drums
Repeatedly pressing and releasing (fanning) the brake pedal may result in: - ANSWER
A loss of brake air pressure
The brake pedal in an air brake system: - ANSWER Controls the air pressure applied to
put on the brakes
You should know that your brakes are fading when: - ANSWER You have to push
harder on the brake pedal to control your speed on a downgrade
Your truck or bus has a dual air break system. If a low air pressure warning comes on
for only one system, what should you do? - ANSWER Stop right away and safely.
Continue only after the system is fixed.
Under ideal conditions, a truck with air brakes going 55 miles per hour would require a
stopping distance of: - ANSWER More than 300 feet
Modern air brake systems combine three different systems. They are the service,
parking, and the _______ brakes. - ANSWER Emergency
Total stopping distance for air brakes is longer than that for hydraulic brakes due to
_____ distance - ANSWER Brake lag
Emergency controlled braking is when when you: - ANSWER Apply the brakes as hard
as you can without locking the wheels.
If you do not have automatic tank drains, how often should you drain the oil and water
from the bottom of compressed air storage air tanks? - ANSWER At the end of each
day of driving
If your vehicle has an alcohol evaporator, every day during cold weather you should: -
ANSWER Check and fill the alcohol level
The most common type of foundation brake found on heavy vehicles is the: - ANSWER
S-cam drum
, The air brake lag distance at 55 miles per hour on dry pavement adds about _____ feet
to your stopping distance - ANSWER 32
The air loss for a straight truck or bus with the engine off and the brakes on should not
be more than: - ANSWER 3 psi in one minute
The air compressor governor controls: - ANSWER When air is pumped into the air
tanks
It is not safe to drive a vehicle that has brake drums (or discs) with cracks that are
longer than _____ the width of the friction area. - ANSWER 1/2
Air braking takes more time than hydraulic braking because air: - ANSWER Takes
more time to flow through the lines than hydraulic fluid
The modulating control valve enables you - ANSWER to put on the spring brakes
gradually.
The S-cam: - ANSWER Forces the brake shoes against the inside of the brake drum.
If your truck's air compressor has its own oil supply, when should you first check the oil
level? - ANSWER Before driving
The supply pressure gauge shows how much pressure: - ANSWER Is in the air tanks
If you must make an emergency stop, you should brake so you: - ANSWER Can steer
and your vehicle stays in a straight line
The brake system that applies and releases the brakes when the driver uses the brake
pedal is the _____ brake system - ANSWER Service
the braking power of the spring brakes: - ANSWER Depends on the service brakes
being in adjustment
To check the free play of manual slack adjusters of S-cam brakes, you should park on: -
ANSWER Level ground, chock the wheels, and release the parking brakes
The driver must be able to see a warning before air pressure in the service air tanks
falls below _____ psi - ANSWER 60
If you are driving down a steep downgrade and you have reached your "safe" speed of
40 mph, you would apply the service brakes until your speed drops to _____ mph -
ANSWER 35
Which of these is NOT a proper time to apply the parking brakes? - ANSWER If the
brakes are very hot (e.g. after coming down a steep grade)
