Louisiana CDL Combination Practice Test (LA) 2

5 out of 5 (37 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Enhance your Commercial Driver's License (CDL) preparation with our Louisiana combination vehicle test. This comprehensive Louisiana driving test practice offers 20 multiple-choice questions on crucial topics like inspection procedures, safe driving practices, and air brake systems. With no time limits, you can take your time understanding each question, ensuring thorough preparation. The goal is to answer at least 16 questions correctly to pass, boosting your confidence and readiness for the permit test. Our Louisiana combination CDL test stands out by offering a diverse range of questions, drawing from a vast pool to cover all necessary aspects of the DMV written test. This extensive variety ensures that you're not just memorizing answers but genuinely understanding the material, which is essential for real-world application. Driving in Louisiana presents unique challenges and conditions, from navigating the bustling streets of New Orleans to handling the long, flat highways stretching through rural areas and bayous. Understanding the risks of jackknifing, where the trailer swings out of alignment with the tractor, is particularly vital. Our Louisiana combination CDL test includes scenarios to help you learn how to avoid this dangerous situation through smooth braking and careful handling, which is crucial for safe driving in any part of the state. The Louisiana DMV practice test is available online, 24 hours a day, 7 days a week, providing unparalleled convenience. You can access it whenever it fits into your schedule, making it easier to integrate your study time with your daily routine. This flexibility is particularly beneficial for those balancing work, family, and other commitments. Incorporating real-world conditions and focusing on key safety practices, our CDL combination practice test is designed to equip you with the knowledge and skills needed to pass the DMV written test and become a safe, confident commercial driver in Louisiana.
FREE CDL Practice Test App
Pass your Louisiana CDL Combination Vehicles test with the NextDoorDriving app. Real questions and answers—100% free and ad-free.
Download on the App Store

Sample Louisiana Combination Test Questions

Question 1

Which pair of actions helps prevent a combination vehicle from rolling over?

  1. A Place cargo near the front and accelerate through turns
  2. B Keep cargo low and drive slowly through turns
  3. C Place cargo near the rear and maintain the posted speed
  4. D Keep cargo high and avoid using the brakes

Correct answer: B – Keep cargo low and drive slowly through turns

The Louisiana manual emphasizes keeping cargo as close to the ground as possible and slowing before and through turns. Stacking cargo higher raises the vehicle’s center of gravity and makes rollover more likely. The load should also be centered and spread out to prevent the trailer from leaning toward one side.

Source: Louisiana Commercial Driver License Manual — § 6.1.1, “Rollover Risks”

Question 2

With the trailer set at the correct coupling height, what should happen as the tractor backs beneath it?

  1. A The trailer should remain completely motionless vertically
  2. B The kingpin head should rest on top of the fifth wheel
  3. C The landing gear should extend farther
  4. D The tractor should lift the trailer slightly

Correct answer: D – The tractor should lift the trailer slightly

Louisiana’s coupling procedure says the trailer should be low enough for the tractor to lift it slightly while backing underneath. If the trailer is too high, the kingpin may not couple correctly with the fifth wheel. If it is too low, the tractor can strike and damage the trailer’s nose.

Source: Louisiana Commercial Driver License Manual — § 6.4.1, “Coupling Tractor-Semitrailers”

Question 3

What does the trailer air supply control do on a newer combination vehicle?

  1. A Applies only the tractor parking brakes
  2. B Mechanically locks the trailer to the fifth wheel
  3. C Directly prevents all tractor air leaks
  4. D Supplies trailer air when pushed in and shuts it off when pulled out

Correct answer: D – Supplies trailer air when pushed in and shuts it off when pulled out

The trailer air supply control is normally a red, eight-sided knob on newer vehicles. Pushing it in supplies air to the trailer brake system. Pulling it out shuts off the air supply and applies the trailer emergency brakes by controlling the tractor protection valve.

Source: Louisiana Commercial Driver License Manual — § 6.2.3, “Trailer Air Supply Control”

Question 4

How do you supply air to the trailer brake system from the cab?

  1. A Connect the blue service line to the red supply line
  2. B Pull out the trailer air supply control
  3. C Apply only the trailer hand valve
  4. D Push in the trailer air supply control

Correct answer: D – Push in the trailer air supply control

Push in the trailer air supply control to send air to the trailer brake system. The control is normally a red, eight-sided knob on newer combination vehicles. Pulling it out has the opposite effect: it shuts off the air supply and applies the trailer emergency brakes.

Source: Louisiana Commercial Driver License Manual — § 6.2.3, “Trailer Air Supply Control”

Question 5

Compared with an empty rig, how much more likely is a fully loaded rig to roll over in a crash?

  1. A Two times
  2. B Three times
  3. C Five times
  4. D Ten times

Correct answer: D – Ten times

The CDL manual states that a fully loaded rig is ten times more likely to roll over in a crash than an empty rig. Cargo stacked higher raises the center of gravity and makes the vehicle less stable. Keeping cargo low and centered and reducing speed for turns help control that risk.

Source: Louisiana Commercial Driver License Manual — § 6.1.1, “Rollover Risks”

Question 6

If a trailer breaks away and separates both air lines, what should happen to the tractor protection valve?

  1. A It should remain partly open
  2. B It should close
  3. C It should open fully
  4. D It should release the tractor parking brakes

Correct answer: B – It should close

A breakaway causes pressure loss in the trailer emergency line. That loss makes the trailer emergency brakes apply and causes the tractor protection valve to close, usually making the trailer air supply knob pop out. Closing the valve prevents the trailer’s disconnected lines from draining the tractor’s air supply.

Source: Louisiana Commercial Driver License Manual — § 6.2.2, “Tractor Protection Valve”, Louisiana Commercial Driver License Manual — § 6.2.4, “Trailer Air-lines”

More Louisiana CDL Practice Tests
Other CDL Endorsements