CDL Practice Test: Video 5 Answers (25 Questions) — Questions and Answers

Question 1: In a combination vehicle, what should the air pressure loss be with a fully charged air system?

Less than 5 psi per minute
Less than 4 psi per minute
Less than 3 psi per minute (Correct answer)
Less than 2 psi per minute

Correct answer: Less than 3 psi per minute

For a combination vehicle (tractor-trailer), the acceptable air pressure loss during a static air brake test is slightly higher than for a single vehicle due to the increased complexity and number of air lines. With a fully charged system and the brakes applied, the pressure loss should not exceed 3 psi per minute. A greater loss indicates potential leaks in the system, which must be repaired for safe operation.

Question 2: What is the proper way to test the air leakage rate?

Turn off the engine and release the parking brake (Correct answer)
Depress the brake pedal and monitor the air pressure gauge
Leave the engine running and release the parking brake
Fully charge the air system and leave the engine running

Correct answer: Turn off the engine and release the parking brake

Turn off the engine and release the parking brake. You should test for air leakage with a fully-charged air system. You should turn off the engine, release the parking brake, and time the air pressure drop. The loss rate should be less than two psi in one minute for single vehicles and less than three psi in one minute for combination vehicles.

Question 3: Which of the following is the most common type of foundation brake?

Wedge brake
S-cam drum brake (Correct answer)
Disc brake
Anti-lock brake

Correct answer: S-cam drum brake

The S-cam drum brake is the most prevalent type of foundation brake found on heavy-duty commercial vehicles. When air pressure is applied, the S-cam rotates, forcing the brake shoes against the inside of the brake drum, creating friction to slow or stop the vehicle. Its robust and reliable design makes it ideal for commercial applications.

Question 4: What type of air do air brakes use?

Compressed air (Correct answer)
Warm air
Heated air
Decompressed air

Correct answer: Compressed air

Air brake systems operate by using compressed air, which is stored in tanks and then released to activate the brake components. An air compressor builds up the pressure, and when the driver presses the brake pedal, this compressed air is directed to the brake chambers, applying force to stop the vehicle.

Question 5: What psi level is the safety relief valve set to open at?

150 psi (Correct answer)
100 psi
125 psi
60 psi

Correct answer: 150 psi

The safety relief valve is a crucial safety device in the air brake system, designed to protect the air tanks and other components from excessive pressure. It is typically set to open and release air if the pressure in the system exceeds 150 psi, preventing damage or rupture of the air tanks.

Question 6: Which of the following is a reason brakes fade?

Cold weather.
Insufficient heat.
Excessive heat. (Correct answer)
Bad driving.

Correct answer: Excessive heat.

Brake fade occurs when excessive heat builds up in the brake components, typically from prolonged or heavy braking. This heat reduces the effectiveness of the brake linings and drums/rotors, causing the brakes to lose their stopping power. It's a dangerous condition that drivers must avoid by using proper braking techniques, such as downshifting and intermittent braking on long downgrades.

Question 7: It's important for a school bus driver to ensure the emergency exits are _________.

Able to close securely from the inside.
Undamaged.
Operate smoothly.
All of the listed answers. (Correct answer)

Correct answer: All of the listed answers.

For a school bus, emergency exits must be fully functional and safe for immediate use in an emergency. This means they must be undamaged, operate smoothly without sticking, and be able to close securely to prevent accidental opening or drafts during normal operation. A thorough check of all these aspects ensures the safety of the students in case of an evacuation.

Question 8: The suspension system ________.

Regulates the speed of the vehicle.
Compresses air.
Holds up the vehicle and its load. (Correct answer)
Suspends gravity.

Correct answer: Holds up the vehicle and its load.

The suspension system is a critical component of any vehicle, especially commercial trucks. Its primary function is to support the vehicle's weight and its entire load, while also absorbing shocks and vibrations from the road. This ensures a smoother ride, maintains tire contact with the road, and protects the cargo and vehicle structure from damage.

Question 9: Crossbuck signs require you to ______.

Smaller than if you were looking at it directly. (Correct answer)
Upside down.
Exactly as if you were looking at the object directly.
Larger than if you were looking at it directly.

Correct answer: Smaller than if you were looking at it directly.

A crossbuck sign indicates a railroad crossing and requires drivers to yield the right-of-way to any approaching train. This means being prepared to stop if a train is coming, or if the crossing signals are activated. It's a critical safety measure to prevent collisions at railroad tracks, as trains cannot stop quickly.

Question 10: Typically, containerized loads are used _______.

Very stable load with a high center of gravity.
Very unstable load with a high center of gravity. (Correct answer)
Very light load to carry.
Unstable load with a low center of gravity.

Correct answer: Very unstable load with a high center of gravity.

Containerized loads are typically used for intermodal transportation, allowing cargo to be easily transferred between different modes like ships, trains, and trucks without rehandling the contents. They offer increased security, protection from weather, and standardized handling, making them efficient for long-distance and international shipping. This versatility and efficiency are key reasons for their widespread use.

Question 11: Typically, air storage tanks hold enough air to allow the brakes to be used _______ even if the compressor stops working.

A great number of times.
Once.
Ten or twelve times.
Several times. (Correct answer)

Correct answer: Several times.

Air storage tanks in a commercial vehicle's air brake system are designed to hold enough compressed air to allow the brakes to be used several times, even if the air compressor stops working. This reserve capacity provides a crucial safety margin, giving the driver time to safely bring the vehicle to a stop before the air pressure drops too low for effective braking. It is not an unlimited supply, emphasizing the need for prompt action if the compressor fails.

Question 12: The ______ must repair any items in the report that affect safety.

The driver.
The vehicle's dealer only.
Certified specialized mechanics.
The motor carrier. (Correct answer)

Correct answer: The motor carrier.

Drivers are required to complete vehicle inspection reports, noting any defects or issues found. It is the responsibility of the motor carrier, which is the company or individual operating the commercial vehicle, to ensure that any reported items affecting safety are promptly repaired. This ensures that vehicles are maintained in safe operating condition before being dispatched, prioritizing safety over all else.

Question 13: During your vehicle inspection test, make sure the seatbelt ___________.

All of the listed answers. (Correct answer)
Is securely mounted.
Is not ripped or frayed.
Latches properly.

Correct answer: All of the listed answers.

During your vehicle inspection test, a thorough check of the seatbelt is essential for safety and compliance. You must ensure the seatbelt is securely mounted to the vehicle, is not ripped or frayed, and latches properly. These checks confirm that the seatbelt will provide effective restraint in the event of a sudden stop or collision, protecting the driver.

Question 14: Blocking is used in the __________ of a piece of cargo to keep it from sliding.

Back.
All of the listed answers. (Correct answer)
Front.
Sides.

Correct answer: All of the listed answers.

Blocking is a cargo securement technique that uses wood or other materials placed against the front, back, and sides of cargo. Its purpose is to prevent the cargo from sliding or shifting during transit. By securing cargo on all sides, blocking effectively restricts movement and maintains stability, which is crucial for safe transportation.

Question 15: If the ABS in your vehicle malfunctions, you need to remember __________.

To drive normally.
You still have regular brakes.
All of the listed answers. (Correct answer)
Get the ABS serviced as soon as possible.

Correct answer: All of the listed answers.

If the Anti-lock Braking System (ABS) in your vehicle malfunctions, it's important to remember that you still have regular braking capability, although without the benefits of ABS. You should drive normally but get the ABS serviced as soon as possible. ABS is a crucial safety feature designed to prevent wheel lock-up during hard braking, maintaining steering control.

Question 16: You should check the fifth wheel _____.

For damaged parts.
For missing parts.
To ensure the fifth wheel plate is greased.
All of the listed answers. (Correct answer)

Correct answer: All of the listed answers.

A thorough inspection of the fifth wheel is crucial for safety in commercial vehicles. This includes checking for any missing or damaged parts that could compromise the coupling mechanism, as well as ensuring the fifth wheel plate is properly greased. All these checks are vital to prevent trailer detachment and ensure safe operation.

Question 17: When you back up your vehicle, you should assign someone as a lookout, who could warn you of ________.

Approaching persons.
Obstacles.
Other vehicles.
All of the listed answers. (Correct answer)

Correct answer: All of the listed answers.

Backing up a large commercial vehicle like a bus presents significant blind spots and hazards. Assigning a lookout is a critical safety measure to help the driver navigate safely. The lookout's role is to warn the driver of any potential dangers, including approaching persons who might not see the backing vehicle, fixed obstacles that could cause damage, and other vehicles in the path. This comprehensive warning ensures a safer backing maneuver.

Question 18: If you are having difficulty driving in high winds who should you contact?

Your dispatcher. (Correct answer)
No one.
The students' parents.
Your loved ones.

Correct answer: Your dispatcher.

If a bus driver is experiencing difficulty driving in high winds or other adverse weather conditions, they should immediately contact their dispatcher. The dispatcher can provide guidance, authorize route changes, or arrange for assistance, ensuring the safety of both the driver and passengers. It's crucial to communicate such challenges to the appropriate authority for support and decision-making.

Question 19: The air pressure governor cut-out is typically within what psi range?

100-120 psi.
180-200 psi.
120-140 psi. (Correct answer)
50-90 psi.

Correct answer: 120-140 psi.

In an air brake system, the air compressor governor is responsible for maintaining air pressure within a safe operating range. The governor typically cuts out, stopping the compressor, when the air pressure reaches between 120-140 psi. This ensures the system has sufficient pressure for braking while preventing over-pressurization, which could damage components.

Question 20: While driving your bus, you should scan ________ for trouble or hazardous conditions.

The back of your bus.
The road ahead.
The bus' interior.
All of the listed answers. (Correct answer)

Correct answer: All of the listed answers.

A bus driver must constantly scan all areas around the bus for potential trouble or hazardous conditions to ensure comprehensive safety. This includes monitoring the road ahead for traffic and obstacles, checking the bus's interior for passenger behavior or issues, and using mirrors to observe the back of the bus for following traffic and blind spots. Comprehensive scanning allows the driver to anticipate and react effectively to any dangerous situation.

Question 21: Which of the following requires a placard for ANY quantity (Table 1 material)?

Class 3 flammable liquid
Class 9 miscellaneous
Division 1.1 explosives (Correct answer)
Combustible liquid

Correct answer: Division 1.1 explosives

Division 1.1 explosives are Table 1 materials and must be placarded in any amount.

Question 22: To obtain a hazmat endorsement, a driver must also pass:

A TSA security threat assessment (Correct answer)
A swimming test
A trailer-weight inspection
A hearing test only

Correct answer: A TSA security threat assessment

Federal rules require a TSA security threat assessment including a background check for the H endorsement.

Question 23: Poison gas (Division 2.3) shipments must be placarded when the quantity is:

Over 1,001 pounds only
Over 5,000 pounds only
Any amount (Correct answer)
Over 100 pounds only

Correct answer: Any amount

Division 2.3 is a Table 1 material, so any quantity requires a placard.

Question 24: What is the aggregate gross weight threshold at which Table 2 hazardous materials require placarding?

1,001 pounds or more (Correct answer)
5,001 pounds or more
500 pounds or more
2,500 pounds or more

Correct answer: 1,001 pounds or more

Table 2 materials need placards when the aggregate gross weight is 1,001 pounds or more.

Question 25: On a placarded vehicle, placards must be displayed on:

Both sides and both ends of the vehicle (Correct answer)
The cab doors only
The rear and the driver's side only
The front and rear only

Correct answer: Both sides and both ends of the vehicle

Placards go on the front, rear, and both sides of the vehicle.

CDL Practice Test: Video 5 Answers (25 Questions)

In a combination vehicle, what should the air pressure loss be with a fully charged air system?

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Sources & references

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