ELDT - Entry Level Driver Training Vehicle Systems and Malfunctions Questions and Answers 1 — Questions and Answers
Question 1: What is the primary function of the air compressor governor in a vehicle's air brake system?
- To filter moisture and contaminants from the compressed air.
- To control the cut-in and cut-out pressures of the air compressor. (Correct answer)
- To regulate the amount of air pressure sent to the brake chambers during a stop.
- To release excess air pressure if the system becomes overcharged, preventing tank damage.
Correct answer: To control the cut-in and cut-out pressures of the air compressor.
The air compressor governor's specific job is to monitor the air pressure in the reservoirs and signal the compressor when to start pumping air (cut-in) and when to stop (cut-out) to maintain pressure within the correct operating range.
Question 2: A driver is operating on a long, steep downgrade and notices they must press harder on the brake pedal to achieve the same stopping force. The pedal feels firm, but the truck is not slowing as it should. What is this dangerous condition called?
- Brake fade (Correct answer)
- Brake lag
- Air-line freeze-up
- Compressor failure
Correct answer: Brake fade
This scenario describes brake fade, which is a significant loss of stopping power that occurs when excessive heat from prolonged or hard braking reduces the friction between the brake shoes and drums.
Question 3: Which of the following is a common symptom of a failing water pump in the engine's cooling system?
- Black smoke coming from the exhaust pipe.
- The steering wheel becoming difficult to turn.
- A grinding or whining noise from the front of the engine that changes with RPMs. (Correct answer)
- The oil pressure gauge reading unusually high.
Correct answer: A grinding or whining noise from the front of the engine that changes with RPMs.
A failing water pump often has a worn bearing, which can produce a distinct grinding, whining, or squealing noise from the front of the engine that typically increases in pitch or volume as the engine speed increases.
Question 4: While driving at night, a CMV driver notices the headlights are dimming and flickering, and the needle on the voltmeter is steadily dropping. These are primary indicators of a malfunction in which vehicle system?
- The fuel system.
- The hydraulic system.
- The exhaust system.
- The electrical system. (Correct answer)
Correct answer: The electrical system.
Dimming or flickering lights and a dropping voltmeter/ammeter are classic signs of a failing alternator, which is the component responsible for generating electricity and recharging the battery while the engine is running.
Question 5: During a pre-trip inspection, a driver notices it is very difficult to shift into gear and hears a grinding noise, even with the clutch pedal fully depressed. This most likely indicates a problem with the:
- Clutch (Correct answer)
- Engine
- Driveshaft
- Air brakes
Correct answer: Clutch
Difficulty shifting and grinding noises are classic symptoms of a clutch that is failing to disengage properly. This prevents a clean separation of the engine from the transmission, making gear changes difficult and noisy.
Question 6: A driver is on the road when the low air pressure warning light and buzzer activate. What is the most critical and immediate action the driver must take?
- Increase speed to reach the nearest service center quickly.
- Pump the brake pedal rapidly to try and build pressure.
- Find a safe place to pull over and stop the vehicle as soon as possible. (Correct answer)
- Shift to a lower gear to use the engine to help slow down.
Correct answer: Find a safe place to pull over and stop the vehicle as soon as possible.
The low air pressure warning indicates a critical loss of air, which will soon lead to the spring brakes applying automatically and a potential loss of braking control. The only safe and correct response is to stop the vehicle in a safe location immediately to diagnose the problem.
ELDT - Entry Level Driver Training Vehicle Systems and Malfunctions Questions and Answers 1
What is the primary function of the air compressor governor in a vehicle's air brake system?