Instructions

Air Brakes

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

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

Number of Question 25

Passing Score 20

19. If using air tanks with manually operated drains, how often should you drain the tanks?

Every day

Once a week

Once a month

Once every 3,000 miles

To prevent the build up of oil and water in a vehicle's air tanks, manually operated air tank drains should be used at the end of each day of driving.

20. A low air pressure warning signal should activate:

When tank pressure falls below 120 psi.

When tank pressure falls below 55 psi.

When tank pressure falls below 10 psi.

When tank pressure falls below 5 psi.

In an air brake system, a low air pressure warning signal must come on if air pressure in the tanks falls below 55 psi. This warning signal may come in the form of a light, a buzzer, or a wig wag.

21. What do anti-lock brakes do?

Help a driver avoid wheel lockup

Lock up the front wheels

Prevent a vehicle from accelerating while traveling uphill

Prevent a vehicle from accelerating while traveling downhill

The function of an Anti-Lock Braking System (ABS) is to prevent the vehicle's wheels from locking up from hard brake application.

22. The most common type of foundation brake used is the:

S-cam drum brake.

C-cam drum brake.

G-cam disc brake.

P-cam disc brake.

The most common type of foundation brake is an s-cam drum brake.

23. What happens if the air pressure in a system's air tanks falls below 60 psi?

A warning light will come on.

The vehicle will not shift out of gear.

The front lights will flash.

The vehicle should stop.

In an air brake system, a low pressure warning signal should activate if the pressure in the air tanks falls to a level below 60 psi. This signal may be in the form of a warning light or a wig wag.

24. Most heavy-duty vehicles use ____ air brake systems.

Single

Dual

Triple

Quad

The majority of heavy-duty vehicles are equipped with dual air brake systems.

25. Spring brakes come on:

When too much air pressure is lost.

When a control on the dashboard is activated.

When the tires have minimal tread depth.

When the brakes are noisy.

Spring brakes come on automatically when air pressure drops to an unsafe psi level. Instead of waiting for the spring brakes to automatically activate, you should safely exit the road as soon as you notice the low pressure warning signal and bring your vehicle to a stop while you are still able to control the brakes.

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