- Entry Level Driver Training Vehicle Systems and Malfunctions Questions and Answers Flashcards

What should a CMV driver do if the low air pressure warning activates while driving?

Answer: Immediately pull over safely and stop; do not drive until the air system is repaired

A low air pressure warning indicates the air brake system may fail. The driver must stop immediately because below a certain pressure, the spring brakes will apply automatically and the vehicle will have no service brakes.

What is the function of the governor in an air brake system?

Answer: It controls when the air compressor pumps air into the storage tanks

The governor controls the air compressor by cutting it in when tank pressure drops to about 100 psi and cutting it out when pressure reaches about 125 psi, maintaining proper system pressure.

What causes brake fade and how can it be prevented?

Answer: Overheating the brakes from continuous use; prevented by proper gear selection on downgrades

Brake fade occurs when brakes overheat from continuous or excessive use, reducing their friction and stopping power. It is prevented by using proper gear selection and engine braking on long downgrades.

What should you do if your engine overheats while driving?

Answer: Pull over safely, keep the engine idling to circulate coolant, and investigate the cause

If the engine overheats, pull over safely and let the engine idle (if safe to do so) to continue circulating coolant. Do not add cold water to a hot system as it can crack the engine block.

What is the function of the slack adjuster in the air brake system?

Answer: It converts the push rod movement into the rotational force needed to apply the brake shoes

The slack adjuster is a lever that connects the push rod from the brake chamber to the camshaft. It converts the linear push of the rod into rotational force to turn the S-cam and apply the brake shoes against the drum.

What should a driver do if they experience a tire blowout on the highway?

Answer: Grip the steering wheel firmly, stay off the brakes, and gradually slow down before pulling over

During a blowout, grip the steering wheel firmly to counteract the pulling force, do not brake (which can cause a skid), and let the vehicle slow naturally before safely steering to the shoulder.