Air Brakes – Practice Test Questions Flashcards
Why must air tanks be drained?
To release oil and water buildup
What is a supply pressure gauge used for?
To check tank pressure
All vehicles with air brakes must have a low pressure warning signal. True or False?
T
What are spring brakes?
Emergency/parking brake
Front wheel brakes are good under all conditions. True or False?
T
What is a dual air brake system?
2 systems which use a single set of brake controls
What are the slack(a. 松弛的) adjusters?
Adjusts the slack in the brakes
How can you test the low pressure warning signal?
Apply parking brake and pump the brake pedal again and again
How can you check that the spring brakes come on automatically?
Release parking brake and press the brake pedal again and again
What are the maximum leakage rates?
More than 3 psi in one minute
Why should you be in the proper gear before starting down a hill?
The use of brakes is only a supplement to the braking effect of the engine
What factor can cause brakes to fade or fail?
Excessive use of service brakes
The use of brakes on a long steep downgrade is only a supplement to the braking effect of the engine. True or False?
T
If you are away from your vehicle for only a short time, you don’t need to use the parking brake. True or False?
F
How often should you drain air tanks?
At the end of each working day
How do you use the stab braking technique during emergency braking?
Brake hard with the pedal until the wheels lock, then let off until the wheels start rolling again
When using brakes on a long steep downgrade, which of these is True?
Use the engine braking effect, then when the vehicle reaches the safe speed, apply brakes until speed is reduced to about 5 mph below safe speed.
Why should you NOT fan the brakes on and off during long downgrades?
Does not allow brakes to cool
PS: Fanning reduces air pressure and serves no useful purpose on dry pavement, and fanning on a long downhill grade may reduce air pressure below the minimum pressure needed for proper brake operation. … If brakes should fail on a level road, you should downshift and use engine braking to slow the vehicle.
If you must make a quick emergency stop, you should:
Stay in a straight line and maintain control.
A straight truck or bus air brake system cannot leak more than_______psi per minute with engine off and brakes released.
2
A combination vehicle air brake system cannot leak more than ______psi per minute with engine off and brakes released.
3
During normal operations, what are the parking and emergency brakes usually held back by?
When do you use the parking brake in air brake equipped vehicles?
Every time you park the vehicle
If your truck has dual control valves, you can use pressure from a separate tank to
Release emergency brakes to move short distances
If the air system develops a leak, what will keep the air in the tanks?
The one-way check valve
Which of these is normal to find in the air brake system?
Air
What turns on the electrical stop light switch in an air brake system?
Air pressure
If the vehicle is equipped with an alcohol evaporator, what should you do everyday during winter weather?
Check and fill the alcohol level
If a failure occurs in the service brake system, what system do you need to stop the vehicle?
Emergency brake system
What determines how effective the spring emergency brakes or the parking brakes work?
Depends on the adjustment of the service brakes
What does the brake pedal do?
Controls the air pressure to operate the brakes
What does the air compressor governor control?
When the compressor will pump air into the storage tanks
On heavy commercial vehicles, what is the most common type of foundation brake?
S-cam drum
In manual slack adjusters, how do you check the free play(空转)?
Park on level ground, chock wheels, release parking brake and pull slack adjusters
What must air brake equipped vehicles have?
An air pressure gauge to show pressure available for braking
The warning device comes on when the air pressure in the service air tank falls below
60 psi
Air loss in a single vehicle (not comb. vehicle) should not be more than
_____\_with engine off and brakes on.
3 psi in one minute
Three systems are found in modern air brake systems, Service brakes, Parking brakes and:
Emergency brakes
When using parking or emergency brakes, what type of pressure is being used?
Spring pressure
Which brake system applies and releases the brakes when the driver uses the brake pedal?
Service brake system
What does the air supply pressure gauge show?
How much pressure is available in the air tanks
What does an alcohol evaporator do?
Gets rid of alcohol that condenses in the air tanks
What is the purpose of the engine retarders?
Helps slow the vehicle and reduce brake wear
Which of these statements is True about brakes?
The heavier the vehicle or the faster the vehicle is going, the more heat the brakes have to absorb to stop it.