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Air Brake Endorsement Test
If you must make an emergency stop, brake so that you:
Can steer and your vehicle will stay in a straight line.
Use the hand brake before the pedal brake.
Use the full power of the brakes to lock them.
You know your brakes are fading when:
Pressure on the brake pedal is increased and speed increases.
You have to press the brake harder when on a downhill grade.
The brakes feel spongy when pressure is applied.
If the spring brakes are on, when should you press the brake pedal?
Only when driving downhill.
Only on a slippery road.
The use of air brakes on a downgrade is only a supplement to the:
The braking effect of the engine.
Use of the front brake limiting valve.
Use of the spring brakes.
What is the first thing you should do should a low air warning device come on?
Stop and safely park as soon as possible.
Call a mechanic.
If the vehicle has an alcohol evaporator, every day during cold weather, you should:
Check the oil level for alcohol
Check and fill the alcohol level
Change the alcohol from a new bottle
For air brakes in good condition, the air compressor should start pumping about ______ PSI.
Which of these is not a proper time to apply your parking brake?
When you park for less than 1 hour
When you're testing to see if they will hold your vehicle
When your brakes are hot
Repeatedly pressing and releasing the brake pedal (fanning) can result in:
No Change in Brake Pressure
Build-up of Air Pressure
Loss of Air Pressure
It is not safe to drive a vehicle that has brake drums with cracks that are longer than ____ of the width of the friction area.
Excessive use of the service brakes can lead to overheating, which can lead to:
Expansion of the brake drums
Increased contact between the brake drums and brake lining
Improper adjustment of S-cam
During normal operation, spring brakes are held back by:
Bolts and braces
The Air Pressure Governor controls the:
Speed of the air compressor
When air is pumped into the storage tanks
The Air pressure applied to the brakes
In Air brakes, the parking brake should be used:
To hold your Speed going downhill
As little as possible
Anytime the vehicle is parked
What is the slack adjuster?
It is the adjusting controls used to adjust the spring beneath the cab
It is the adjusting controls on the back side of the drum used for adjusting the brakes.
It is the space between the rear wheels.
The brake pedal in an air brake system:
Controls the speed of the air compressor
Controls the amount of air pressure applied to the brakes
Is connected to the slack adjuster
Air Brake-equipped vehicles have:
An Air Use gauge
A back-up hydraulic system
An Air supply pressure gauge
The parking or emergency brake on a heavy vehicle can only be held in position by something that cannot leak away, like:
How should you check that the spring brakes come on when the air pressure in the system drops below a certain level?
Park on level ground, chock the wheels, release the parking brake when you have enough air pressure, shut the engine off, and repeatedly press and release the brake pedal.
Park on a slight incline, drain off air pressure, set the parking brakes, and check for movement.
Park on level ground, wait for normal air pressure, release the parking brake, move the truck forward slowly, and apply the brakes firmly using the brake pedal.
The parking brake applies and releases:
The brake pedal during normal driving
The parking brakes when you use the parking brake control
In the event of an emergency
You should brake in a way that will keep your vehicle in a straight line and allow
you to turn if it becomes necessary. You can use the:
Controlled Braking method
Both the above answers are correct
Stab braking method
Which of the following does ABS do?
Decreases you normal braking ability
Activates when the wheels are about to lock up
Increases your normal braking ability
Shortens your stopping distance
Why must you study air brakes?
otherwise you will have to get a CDL with restrictions
Otherwise you can only receive a CDL permit
All trucks have air brakes
Spring Brakes are:
Come on automatically when the pressure drops too low
Both A & B are correct
Brakes held back by heavy duty springs
How can you tell if your vehicle is equipped with an ABS system?
If the vehicle is manufactured after 2010
If the vehicle is manufactured after 1998
Its still an option on some vehicles
About the Air Brakes CDL Test
The Air Brakes test:
- 25 questions.
- You need 20 correct answers (80%).
- You may be timed. Time limit varies by state.
Many of the commercial vehicles on the road today use air brakes for their braking system. If you want to pull a trailer with air brakes, you will need to pass the Air Brakes test.
You should also study the Combination Vehicle section of your state’s CDL manual. It is a great idea to study for and pass this exam to broaden your marketability in the trucking industry, as well to be as knowledgeable about other commercial vehicles on the road around you.
The air brakes test is not technically an endorsement. Instead, air brakes are a restriction. If you cannot pass this test, you are restricted from driving vehicles that use air brakes.
Air brakes use compressed air instead of a hydraulic system to stop your vehicle. The air brake system is a three-part system, engaging at different times the service brake, parking brake, and/or emergency brake. The service brake is using the compressed air when you use your foot to depress the brake pedal. The parking brake engages the air supply when you pull on the push/pull knob inside the cab, usually on the dash. Finally, the emergency brake uses a separate air supply to engage parts of both the service and parking brakes to stop the vehicle in an emergency.
There are some images of the different parts of all three braking systems inside the CDL manual. Even for some of you with mechanical backgrounds, studying these images and knowing everything about them will improve your understanding of the brakes, and make you a safer operator.
You will be tested on the following:
- The parts of an air brake system
- Dual air brake
- Inspecting air brake systems
- Using air brakes
Knowing your braking system is very important—they have a separate test all about one feature of your vehicle! Some sample questions are as follows. Why must air tanks be drained? What are slack adjusters? How should you brake when driving a tractor-trailer combination with ABS?