Louisiana CDL Combination Test (LA) 2026

4.8 out of 5 (46 votes)
80% Passing score
20 Questions
4 Mistakes allowed
If you're preparing for your Commercial Driver's License (CDL) combination vehicles endorsement in Louisiana, our comprehensive Louisiana DMV practice test is exactly what you need. This test is specifically designed to cover all critical areas such as coupling and uncoupling, pre-trip inspections, driving techniques, backing and maneuvering, and air brake systems. Each Louisiana combination CDL test comprises 20 multiple-choice questions, and you must answer at least 16 correctly to pass. Our Louisiana combination vehicle test focuses on the specific endorsement and includes only questions that you will encounter on the actual CDL permit test. It's essential to master these topics, especially understanding the increased stopping distances required for combination vehicles due to their greater weight. This knowledge is crucial for maintaining safety on the road and handling the unique challenges of driving larger, heavier vehicles. At the end of the Louisiana driving test practice, you'll receive a detailed summary of your performance. This summary will highlight the questions you answered incorrectly and provide the correct answers for your review. This feedback is designed to enhance your learning experience and ensure you're thoroughly prepared for the real test. Our permit practice test questions have been meticulously crafted and reviewed by professional driving instructors with decades of combined teaching experience. These experts have helped thousands of drivers obtain their commercial licenses, ensuring that our questions are both accurate and practical. It's important to note that passing the CDL combination test is just one step in obtaining your commercial driver's license. You must also pass the general knowledge test. If you need to study for the CDL general knowledge test, we offer a range of general knowledge prep tests to help you succeed. Prepare confidently for your CDL with our expertly designed Louisiana combination vehicle test and ensure you have the knowledge and skills to drive safely and effectively.
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Sample Louisiana Combination Test Questions

Question 1

The trailer hand valve should normally be used for which task?

  1. A Making emergency stops
  2. B Holding the trailer while parked
  3. C Slowing only the trailer on downgrades
  4. D Testing the trailer brakes

Correct answer: D – Testing the trailer brakes

The trailer hand valve, also called a trolley valve, should be used only to test the trailer brakes. Using it while driving can make the trailer skid because it applies the trailer brakes without applying the tractor brakes. Normal braking should be controlled with the foot pedal, which applies the brakes throughout the combination.

Source: Louisiana Commercial Driver License Manual — § 6.2.1, “Trailer Hand Valve”

Question 2

While coupling, why must the air lines be safely supported before the tractor backs under the trailer?

  1. A To keep them from being crushed or caught
  2. B To reduce fuel consumption
  3. C To prevent tire wear
  4. D To raise the landing gear automatically

Correct answer: A – To keep them from being crushed or caught

The Louisiana coupling procedure requires the air lines to be supported where they will not be crushed or caught as the tractor backs under the trailer. After coupling, the lines should also be checked for damage and kept away from moving parts. They must have enough slack for turns without hanging where they can be damaged.

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

Question 3

Which statement may be true of a converter dolly or trailer built before 1975?

  1. A It may have no spring brakes
  2. B It must have an antilock braking system
  3. C Its emergency brakes operate only from tractor air
  4. D It always has a separate parking brake

Correct answer: A – It may have no spring brakes

Some converter dollies and trailers built before 1975 may not have spring brakes. Their emergency brakes operate using air stored in the trailer tank and apply when pressure in the emergency line is lost. Because stored air can eventually leak away and release those brakes, wheel chocks are needed when parking such a trailer.

Source: Louisiana Commercial Driver License Manual — § 6.2.8, “Trailer Service, Parking and Emergency Brakes”

Question 4

Why should the trailer hand valve not be used to park a trailer that lacks spring brakes?

  1. A Stored air may leak away and release the brakes
  2. B It can unlock the fifth wheel
  3. C It drains fuel from the tractor
  4. D It raises the trailer landing gear

Correct answer: A – Stored air may leak away and release the brakes

On a trailer without spring brakes, the hand valve applies brakes that depend on stored air pressure. That air may leak away over time, allowing the brakes to release and the trailer to move. Use the parking brakes when available, and use wheel chocks to secure a trailer that has no spring brakes.

Source: Louisiana Commercial Driver License Manual — § 6.2.1, “Trailer Hand Valve”

Question 5

Before connecting the air lines, which condition must you verify at the glad hands?

  1. A The couplers are lubricated with engine oil
  2. B Both lines use the same identifying color
  3. C The seals have been removed for inspection
  4. D The couplers and rubber seals are clean and intact

Correct answer: D – The couplers and rubber seals are clean and intact

Glad hands connect the tractor’s service and emergency air lines to the trailer. Their rubber seals prevent air from escaping, so the couplers and seals should be cleaned and checked before connection. The correct lines must also be matched—blue normally identifies the service line and red identifies the emergency or supply line.

Source: Louisiana Commercial Driver License Manual — § 6.2.5, “Hose Couplers (Glad Hands)”

Question 6

If a trailer breaks away and tears apart the emergency air line, what should the tractor protection system do?

  1. A Allow all tractor air pressure to escape
  2. B Keep the trailer air supply open
  3. C Lock the tractor brakes immediately
  4. D Retain air so the tractor brakes remain available

Correct answer: D – Retain air so the tractor brakes remain available

Loss of pressure in the emergency line causes the trailer emergency brakes to apply and the tractor protection valve to close. Closing the valve stops air from escaping the tractor or truck brake system. This preserves the tractor’s air supply rather than allowing the breakaway trailer to drain it.

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

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