In an air brake system, the air tanks must be periodically drained to remove accumulations of water and compressor oil. If water is not removed, it could freeze in cold weather and cause brake failure.

Water accumulations freezing and causing brake failure.

Too much air collecting in the tanks.

Because air takes time to flow through the air lines to the brakes, air brakes cannot begin working instantly. There is often a brake lag of at least one-half of a second between the moment the brake pedal is pressed and the moment the brakes begin to work.

The time required for the brakes to work after the brake pedal is pressed

The distance between the brake pedal and the floor

The amount of air pressure used to stop the vehicle

Vehicles with air brakes are required to be equipped with a low pressure warning device. A wig wag is a type of low air pressure warning device. This device drops a mechanical arm into the driver's view if the pressure in the tanks drops to a level between 55 and 75 psi.

A tube that carries air to the brakes.

An air brake system has a safety relief valve, which releases air from the tanks if the pressure gets too high. If the valve must operate, something in the system is wrong and should be addressed by a mechanic.

The air pressure has become too high.

The brakes are fully operational.

Friction inside a brake drum is caused when the brake shoes and linings push against the inside of the drum. The friction in the drums will slow and stop the vehicle.

Press against the inside of the brake drum.

Press against the outside of the brake drum.

Press against the inside of the brake drum.

Air Brakes Endorsement Test | Missouri 2024 #1 Page 3 of 4

Train for FREE online with our Missouri CDL air brake test. The official exam test consists of several obligatory parts, with all of them checking your knowledge of different blocks of road rules. If you need to obtain a MO Class A/Class B driver license in 2024, practice as much as possible. Free sample tests published on our website will help you check and improve your knowledge and boost your grades. Please bear in mind that the requirements for CDL may vary from state to state.

Number of Question 25

Passing Score 20

Number of Tests 20

Air Brakes Endorsement Test | Missouri 2024 #1 Page 3 of 4

13 . Failing to drain air tanks could result in:

14 . What is brake lag?

15 . Vehicles equipped with Anti-Lock Braking Systems (ABS) have ____ malfunction lamps to indicate when the ABS is not working.

16 . A wig wag is:

17 . If the safety relief valve in the air brake system releases air:

18 . Friction in an S-cam brake is caused when the brake shoes and linings:

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