Entry Level Driver Training Vehicle Systems and Malfunctions 1 Flashcards

What is the purpose of the tractor protection valve in an air brake system?

Answer: To automatically close and protect the tractor's air supply if the trailer breaks away or develops a major leak

The tractor protection valve closes automatically when air pressure drops to a critical level (typically 20–45 psi), isolating the tractor's air supply from the trailer to keep the tractor's brakes functional if the trailer separates or suffers a catastrophic air loss.

Which of the following is the correct action when you notice your vehicle pulling to one side during brake application?

Answer: Pull off the road safely, inspect for a brake adjustment or mechanical issue, and have it repaired before continuing

Pulling to one side during braking indicates uneven brake adjustment, a dragging brake, or a mechanical defect on one side. This is a safety hazard that must be diagnosed and corrected before operating the vehicle further, as it can cause loss of directional control.

What does a continuous or repeated activation of the ABS (Anti-lock Braking System) warning light while driving indicate?

Answer: A fault has been detected in the ABS system that requires inspection and service

The ABS warning light illuminates briefly at startup for a self-test, but if it stays on or reactivates while driving, it signals a detected fault in the ABS system. The base brakes still function, but the anti-lock feature may be disabled, requiring prompt inspection.

What is the primary danger of a tire blowout on a front steer axle of a CMV?

Answer: Sudden loss of directional control that can cause the vehicle to veer sharply

A front steer axle blowout is particularly dangerous because steering input is transmitted directly through the front tires. A sudden loss of air causes immediate loss of steering control, requiring the driver to firmly grip the wheel, avoid sudden braking, and gradually slow the vehicle to a safe stop.

If you notice steam or smoke coming from the wheel area of your vehicle while driving, what is the most likely cause and appropriate action?

Answer: A dragging or overheated brake; pull off safely, allow it to cool, and inspect before continuing

Steam or smoke from the wheel area is a strong indicator of a dragging brake or severely overheated brake drum. Continuing to drive risks brake failure, fire, or structural damage to the wheel end. The driver must stop safely, allow cooling, and inspect before proceeding.

What should a CMV driver do if the oil pressure warning light illuminates while driving on the highway?

Answer: Safely reduce speed, activate hazard lights, pull off the road, and shut down the engine as quickly as safely possible

A low oil pressure warning indicates insufficient lubrication reaching engine components. Continued operation can cause catastrophic and irreversible engine damage within seconds to minutes. The driver must get off the road and shut the engine down promptly to prevent engine destruction.