# Air Brakes

This endorsement is required for driving a vehicle with air brakes. To receive this endorsement, applicants must pass a written test. The test consists of 25 multiple choice..

This endorsement is required for driving a vehicle with air brakes. To receive this endorsement, applicants must pass a written test. The test consists of 25 multiple choice questions. Each question has two, three or four answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Nebraska Commercial Driver License Manual. Questions come from the chapter covering: Air Brakes. The Air Brakes endorsement may be used with the Class A, B or C CDL.

Number of Question
Passing Score

### 1. A low air pressure warning signal:

Explanation
Any vehicle with air brakes must be equipped with a low air pressure warning signal.

### 2. Air brakes use ____ to function.

Explanation
The brakes in an air brake system use compressed air to function properly.

### 3. During a static leakage test, what is the maximum leakage rate that is safe for a double combination vehicle?

Explanation
When performing a static leakage test on a double combination vehicle with air brakes, the leakage rate should be no more than 3 psi in one minute. If the air leaks from the air brake system at a quicker rate, the vehicle should not be driven because something likely needs to be repaired.

### 4. While driving downhill, you should brake until you reach a speed that is ____ below your safe speed, then release the brake pedal.

Explanation
While driving downhill, you should hold down the brake pedal until your vehicle reaches a speed 5 mph below your safe speed, then release the brake pedal. Repeat this process.

### 5. You should ____ if the low pressure warning signal activates while you are driving.

Explanation
If the low pressure warning signal activates while you are driving, it is important that you safely exit the roadway as soon as possible and park your vehicle. If the air pressure gets too low, the brakes will no longer work well enough for you to stop safely.

### 6. When using the controlled braking method in an emergency situation, you should:

Explanation
The controlled braking method for emergency stops involves applying the brakes as hard as you can without locking the wheels. Keep steering wheel movements small when braking in this way.