SD CDL - South Dakota Commercial Drivers License Air Brake Systems Questions and Answers

Question 1

During a static air brake leakage test on a single vehicle, what is the maximum permissible pressure drop in one minute after the initial drop?

Accepted Answer

2 psi

Answer

5 psi

Answer

10 psi

Answer

1 psi

Question 2

A driver is operating a truck with a dual air brake system. The low air pressure warning light and buzzer activate. What is the most likely pressure range in one of the systems?

Accepted Answer

Below 60 psi

Answer

80-90 psi

Answer

100-120 psi

Answer

20-45 psi

Question 3

Which of the following components is responsible for stopping the air compressor from pumping air when the storage tanks reach their maximum pressure?

Accepted Answer

The air compressor governor

Answer

The safety valve

Answer

The brake pedal

Answer

The slack adjuster

Question 4

A driver is preparing for their pre-trip inspection. If the vehicle is equipped with an alcohol evaporator, what is its primary function?

Accepted Answer

To reduce the risk of ice forming in air brake valves during cold weather

Answer

To clean the air going into the tanks

Answer

To inject alcohol into the fuel system for better combustion

Answer

To cool the air compressed by the engine

Question 5

Under normal driving conditions, what holds the spring brakes in the released position?

Accepted Answer

Air pressure

Answer

Hydraulic pressure

Answer

Mechanical linkage from the brake pedal

Answer

The driver manually holding a lever

Question 6

When descending a long, steep grade, a driver should brake until the vehicle's speed is about 5 mph below the 'safe speed' and then release the brakes. Why is this 'snub braking' technique recommended?

Accepted Answer

To allow the brake drums to cool and prevent brake fade

Answer

To keep the air pressure from dropping too quickly

Answer

To ensure the trailer brakes are working harder than the tractor brakes

Answer

To dry out wet brake linings