What is the primary purpose of a front brake limiting valve?
Correct answer(s):
- Cuts the air pressure to the front brakes by half
Topic
Air Brakes Test
If you plan on driving any CMV equipped with air brakes, you must take and pass the air brakes test to remove the air brakes restriction from your CDL. The air brakes test is different than the endorsement tests because the air brakes test works as a restriction instead of an endorsement. If you do not pass the air brakes test, your CDL will bear a mark of restriction which means that you are not authorized to drive a CMV with air brakes.
Quizzes in Air Brakes Test
Which of the following will affect the stopping power of spring brakes?
Correct answer(s):
- Road conditions
- Proper adjustment
- Modulating control valve position (if equipped)
A dual air brake system has which of the following features?
Correct answer(s):
- One set of brake controls and two separate air brake systems
Where are foundation brakes used?
Correct answer(s):
- On all wheels
Which of the following parts of the air brake systems should be checked during the pre-trip walk around inspection?
Correct answer(s):
- Slack adjusters on S-cam brakes
- Air hoses connected to the brake chambers
- Brake discs or drums
During inspection, if a slack adjuster moves less than about one inch where the push rod attaches to it, which of the following statements is true?
Correct answer(s):
- It has the appropriate amount of slack
When testing the air leakage rate (by turning off the engine and releasing the parking brake), what is an acceptable air loss rate?
Correct answer(s):
- Less than 2 psi in one minute for single vehicles and less than 3 psi in one minute for combination vehicles.
Which of the following is not a step in testing that the spring brakes come on automatically?
Correct answer(s):
- Pull out the parking brake control knob
If you use controlled braking, which of the following is an acceptable procedure?
Correct answer(s):
- Release the brakes if you need to make a large steering adjustment
What should you do if the low air pressure warning light comes on?
Correct answer(s):
- Stop and safely park your vehicle as quickly as possible
What is the proper technique to use when braking on downgrades?
Correct answer(s):
- Apply the brakes just hard enough to slow down about 5 mph below your safe speed
If your vehicle does not have automatic air tank drains, how often should you drain the tanks?
Correct answer(s):
- At the end of each working day
When is it acceptable to not use parking brakes if you have to leave your vehicle unattended?
Correct answer(s):
- You should never leave your vehicle without using parking brakes or chocking the wheels
When should parking brakes NOT be used?
Correct answer(s):
- When the brakes are wet in freezing temperatures
- When the brakes are very hot
- When checking that the spring brakes can come on automatically
Which device is designed to protect the air tank and system from too much pressure?
Correct answer(s):
- Safety valve
What should you do before driving a vehicle with a dual air system?
Correct answer(s):
- Make sure that both primary and secondary system build up to 100 psi
If you press and release the brake pedal rapidly, what will happen?
Correct answer(s):
- You can let the air out faster than the compressor can replace it
What is another term for a brake pedal?
Correct answer(s):
- Treadle valve
What is the name of the device that controls when the air compressor will pump air into the air storage tanks?
Correct answer(s):
- Governor
Which device helps reduce the risk of ice in the air brake systems during cold weather?
Correct answer(s):
- Alcohol evaporator