1
The air compressor governor controls:
a) The speed of the air compressor.
b) Air pressure applied to the brakes.
c) When air is pumped into the air tanks.
c) When air is pumped into the air tanks.
The governor controls when the air compressor will pump air into the air storage tanks. When air tank pressure rises to the "cut-out" level around 125 psi, the governor stops the compressor from pumping air. When the tank pressure falls to the "cut-in" pressure around 100 psi, the governor allows the compressor to start pumping again.
Air brake equipped vehicles must have:
a) An air use gauge.
b) A supply pressure gauge.
c) At least two brake heaters.
b) A supply pressure gauge.
The most common type of foundation brakes found on heavy vehicles is the:
a) Disc brakes
b) Wedge drum
c) S-cam brake
c) S-cam brake
Air brakes use to make the brakes work.
a) Compressed air
b) Released air
c) Stored air
d) Combusted air
a) Compressed air
What does the alcohol evaporator do?
a. Pumps air into the air storage tanks
b. Protects the tank and the rest of the system from too much pressure
c. Puts alcohol into the air system to help reduce the risk of ice in air brake valves and other parts during cold weather
d. All of the above
c. Puts alcohol into the air system to help reduce the risk of ice in air brake valves and other parts during cold weather
The modulating control valve is?
a) A spring-loaded valve that will let you put on the brakes on slowly if the service brakes fail.
b) There is no such thing.
c) Should not be used because it is very unsafe.
a) A spring-loaded valve that will let you put on the brakes on slowly if the service brakes fail.
When the spring brakes are on, what should you not do?
a) Push the brake pedal down
b) Put on the parking brake
c) Honk the horn
d) None of the above
a) Push the brake pedal down
When the tank pressure falls to the "cut-in" pressure, the governor allows the compressor to start pumping again. What is the "cut-in" level?
a. Around 125 pounds per square inch
b. Around 100 pounds per square inch
c. Around 50 pounds per square inch
d. None of the above
b. Around 100 pounds per square inch
How can you tell if your vehicle is equipped with an antilock braking system (ABS)?
a) Check if the vehicle was manufactured after 2000.
b) Check if the vehicle was manufactured after 2010.
c) ABS is still optional.
d) Check if the vehicle was manufactured after 1998.
d) Check if the vehicle was manufactured after 1998.
If you must make an emergency stop, you should brake so that you:
a) Can steer hard while braking hard.
b) Use the full power of the brakes and lock them.
c) Stay in a straight line and can steer.
c) Stay in a straight line and can steer.
The driver must be able to see a warning that is given before air pressure in the service air tanks falls below:
a) 20 psi
b) 40 psi
c) 60 psi
c) 60 psi
An air brake system safety relief valve opens at about:
a) 80 psib)120 psi
c)150 psi
c)150 psi
Spring brakes are
a) brakes that come on automatically on a truck or tractor when the psi drops too low.
b) made up of powerful springs that are held back by air pressure while you are driving.
c) not going to take full effect until your psi drops to a certain range, typically 20 to 30 psi.
d) all of the above.
d) all of the above.
EXPLANATION:
Spring brakes are an important backup system: powerful springs that automatically apply the brakes if they sense that air pressure has been lost for some reason, such as a leak. They will also apply the brakes if the psi gets too low, although ideally, you should take control of your brakes before that happens.
To stop, the brake shoes and linings are pushed against the inside of the drum. True or False?
True
S-cam drum brakes have an S-cam in each brake chamber. Why is it called an "S-cam?"
a) It is shaped like the letter "S."
b) It makes the brake shoes move in an S-shaped path.
c) It is constantly spinning whenever the wheel is spinning.
a) It is shaped like the letter "S."
How can you check the slack adjusters?
a) Use gloves and pull hard on each slack adjuster. If the slack adjuster moves more than about one inch where the push rod attaches to it, adjust it
b) Check the slack adjusters by looking to make sure they aren't cut or worn due to rubbing
c) Check the slack adjusters by looking to ensure they are not soaked with oil or grease
a) Use gloves and pull hard on each slack adjuster. If the slack adjuster moves more than about one inch where the push rod attaches to it, adjust it
lf the low air pressure warning comes on, what should you
a) Stop and safely park your vehicle as soon as possible
b) Continue driving until the spring brake comes on
c) Continue driving but be prepared to use parking brake if needed to stop
d) None of the above
a) Stop and safely park your vehicle as soon as possible
What is the stab braking method?
a) You apply the brakes as hard as you can without locking
b) You apply your brakes all the way, release the brakes when wheel lock up, and as soon as the wheels start rolling again, apply the brakes fully again
b) You apply your brakes all the way, release the brakes when wheel lock up, and as soon as the wheels start rolling again, apply the brakes fully again
What turns on your brake lights at the back of your vehicle?
a) Brake light switch
b) Head light switch
c) Stop light switch
c) Stop light switch
What factors can cause brakes to fade or fail?
a) Excessive use of service brakes
b) Out of adjustment brakes
c) Excessive heat caused by using them too much and not relying on the braking effect
d) All of the above
d) All of the above
If your vehicle has a properly functioning dual air brake system and minimum-sized air tanks, the air pressure should build from 85 to 100 psi within ____ seconds.
a) 60
b) 20
c) 45
c) 45
When you press the brake pedal,
a) compressed air enters the brake chambers.
b) compressed air is released from the air tanks.
c) compressed air is released from the brake chambers.
c) compressed air is released from the brake chambers.
What is the S-cam used for?
a) To release the brakes.
b) To test the slack adjusters.
c) To apply the brakes.
c) To apply the brakes.
EXPLANATION:
When you push the brake pedal, air is let into each brake chamber. Air pressure pushes the rod out, moving the slack adjuster, thus twisting the brake camshaft. This turns the s-cam forcing the brake shoes away from one another and presses them against the inside of the brake drum.
What are the maximum leakage rates?
a) If the air pressure falls more than 3 psi in one minute for single vehicles, then the air loss rate is too much
b) If the air pressure falls more than 30 psi in one minute for single vehicles, then the air loss is too much
c) If the air pressure falls more than 50 psi in one minute for single vehicles, then the air loss rate is too much
a) If the air pressure falls more than 3 psi in one minute for single vehicles, then the air loss rate is too much
The air brake lag distance at 55 mph on dry pavement adds about 32 feet. So at 55 mph for an average driver under good traction and brake conditions, the total stopping distance is over 300 feet, or longer than a football field. True or False?
True