CDL General Knowledge Practice Test 5 — Questions and Answers
Question 1: Which of the following is NOT a required emergency equipment must you have?
- Fire extinguisher
- Warning devices for parked vehicles
- Glass breaking device (Correct answer)
- Spare electrical fuses (or circuit breakers)
Correct answer: Glass breaking device
While a fire extinguisher, warning devices (like reflective triangles), and spare electrical fuses are mandatory emergency equipment for commercial vehicles, a glass breaking device is not a federally required item. Although it might be useful, it's not part of the standard regulatory requirements.
Question 2: Which of the following is a condition in which you should downshift?
- Before starting down a hill (Correct answer)
- Before accelerating
- After starting down a hill
- After starting up a hill
Correct answer: Before starting down a hill
Downshifting before starting down a hill is crucial for controlling vehicle speed and preventing brake fade. By engaging a lower gear, the engine provides significant braking power (engine braking), reducing the need for constant use of the service brakes and helping to maintain a safe speed on descents.
Question 3: Where should you place your reflectors when stopped on a un-divided highway or two lane road carrying traffic in both directions?
- 10' ahead, 10' behind and 100' toward approaching traffic
- 10', 100', 200' toward approaching traffic
- 10', 50', 100' behind your vehicle
- 100' behind and ahead of your vehicle and within 10' of the front or rear corner (Correct answer)
Correct answer: 100' behind and ahead of your vehicle and within 10' of the front or rear corner
On an undivided highway or two-lane road with traffic in both directions, warning devices must alert traffic from both directions. The correct placement is one reflector within 10 feet of the front or rear corner of the vehicle, and then one 100 feet behind and one 100 feet ahead of the vehicle.
Question 4: Which of the following represents the best way to make a right turn if you have a large vehicle that cannot make the turn without swinging into another lane.
- Diagram A
- Diagram B
- Diagram C (Correct answer)
- Diagram D
Correct answer: Diagram C
For large vehicles, Diagram C typically illustrates the 'buttonhook' or 'jug handle' right turn. This technique involves swinging wide *after* entering the intersection, allowing the rear of the trailer to clear the corner without hitting the curb or other objects, and without swinging into the left lane before the turn.
Question 5: ________ can cause lack of braking power, wheel lockups, pulling to one side or the other, and jackknifing.
- Overheated tires
- Bleeding tar
- Wet brakes (Correct answer)
- Loose engine belts
Correct answer: Wet brakes
Wet brakes can significantly reduce friction between the brake linings and drums/rotors, leading to a lack of braking power. This can cause uneven braking, resulting in wheel lockups, the vehicle pulling to one side, or even jackknifing in articulated vehicles, making them extremely dangerous.
Question 6: Engine braking is most effective when:
- RPMs are low and transmission gear is high
- RPMs are high and transmission gear is low (Correct answer)
- RPMs are low and transmission gear is low
- RPMs are high and transmission gear is high
Correct answer: RPMs are high and transmission gear is low
Engine braking is most effective when the engine is operating at high RPMs and the transmission is in a low gear. This combination maximizes the engine's resistance against the vehicle's momentum, providing the greatest amount of braking force without using the service brakes.
Question 7: If your brakes fail, which of the following is NOT a useful method to slow your vehicle?
- Pump the brakes
- Put the vehicle in a higher gear (Correct answer)
- Use the parking brake
- Use an escape ramp
Correct answer: Put the vehicle in a higher gear
If your brakes fail, putting the vehicle in a *higher* gear would reduce engine braking, causing the vehicle to accelerate rather than slow down. To slow the vehicle, you would want to downshift to a lower gear to maximize engine braking, pump the brakes, use the parking brake, or find an escape ramp.
Question 8: With an engine fire, you should do all of the following EXCEPT?
- Turn off the engine as soon as you can
- Open the hood to allow air in (Correct answer)
- Shoot foam through the louvers, radiator or the vehicle's underside
- Pull off the road as soon as possible
Correct answer: Open the hood to allow air in
When dealing with an engine fire, opening the hood allows oxygen to rush in, which can intensify the flames and make the fire much harder to extinguish. The recommended procedure is to keep the hood closed as much as possible and direct the extinguisher agent through any available openings like the grille or underside.
Question 9: The cumulative effect of not getting enough sleep is known as ____?
- Sleep debt (Correct answer)
- Insomnia
- Sleep apnea
- Micro-sleep
Correct answer: Sleep debt
Sleep debt refers to the cumulative effect of not getting enough sleep over a period of time. This deficit builds up, leading to increased fatigue, impaired cognitive function, reduced reaction time, and a higher risk of accidents for drivers.
Question 10: Cargo such as dry bulk or hanging meat
- Require no special driving attention
- Have high centers of gravity and are unstable loads (Correct answer)
- Require special transit permits
- Have low centers of gravity and can lean on curves
Correct answer: Have high centers of gravity and are unstable loads
Cargo such as dry bulk (like grain) or hanging meat can shift easily and often have a high center of gravity. These characteristics make them unstable loads, significantly increasing the risk of rollovers, especially when taking curves or making sudden maneuvers.
CDL General Knowledge Practice Test 5
Which of the following is NOT a required emergency equipment must you have?