North Dakota CDL Combination Practice Test (ND) 2

5 out of 5 (40 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Prepare for your Commercial Driver's License with our second ND DMV practice test, designed to give you a comprehensive review of essential topics. This test consists of 20 multiple-choice questions, focusing on critical areas such as inspection procedures, safe driving practices, air brake systems, and the hazards of jackknifing. To pass, you need to answer at least 16 questions correctly. The varied questions in this CDL combination practice test will significantly boost your confidence and ensure you are well-prepared for the permit test. What sets our North Dakota practice permit test apart is the reliability and thoroughness of our study tools. While some resources might offer cheat sheets that claim to have all the answers, these materials often come with questionable authenticity and legality. They can be a risky and costly approach without any guaranteed outcomes. Instead, our drivers permit practice test is a lawful and trusted resource with a verified history of effectiveness, giving you a robust foundation for your test preparation. The questions on this ND combination vehicle test closely mimic those found on the real permit test, both in format and content. This similarity helps you familiarize yourself with the types of questions you'll encounter, making the actual test day much less intimidating. Upon completing the North Dakota combination CDL test, you'll have the opportunity to review your answers, including hints and explanations for any questions you missed, which reinforces your learning and helps you understand where you need further study. ND's diverse driving conditions make it crucial to prepare thoroughly. From the oil fields in the west to the agricultural heartland in the east, and the challenging winter weather across the state, drivers must be adept at handling various situations. This North Dakota combination CDL test includes scenarios that reflect these unique conditions, ensuring you're ready for anything the state's roads might throw at you. By practicing with this combination CDL practice test, you're taking an important step toward becoming a safe and competent commercial driver in ND.
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Sample North Dakota Combination Test Questions

Question 1

What is the tractor protection valve designed to do?

  1. A. Increase engine efficiency while pulling a trailer
  2. B. Balance tire wear between the tractor and trailer
  3. C. Keep air in the tractor brake system if the trailer separates or develops a major leak
  4. D. Provide additional power-steering pressure

Correct answer: C. – Keep air in the tractor brake system if the trailer separates or develops a major leak

The tractor protection valve closes to keep air from escaping the tractor brake system if a trailer breaks away or develops a major leak. It is operated through the trailer air-supply control in the cab. The valve also closes automatically when system pressure becomes sufficiently low.

Source: North Dakota Commercial Driver License Manual (2025–2027) — § 6.2.2, “Tractor Protection Valve”

Question 2

What is the earliest and best way to recognize that a trailer has begun to skid?

  1. A. Listen for tire squeal
  2. B. Wait for a jolt at the rear of the tractor
  3. C. Watch the trailer in the mirrors
  4. D. Feel for movement in the steering wheel

Correct answer: C. – Watch the trailer in the mirrors

North Dakota’s CDL manual identifies the mirrors as the earliest and best way to detect a trailer skid. Check them whenever braking hard to verify that the trailer remains in its proper path. Once a skidding trailer swings outside its lane, preventing a jackknife becomes much more difficult.

Source: North Dakota Commercial Driver License Manual (2025–2027) — § 6.1.5, “Prevent Trailer Skids”

Question 3

What should a tractor protection valve test verify?

  1. A. The valve reduces fuel consumption
  2. B. The valve equalizes tire pressure
  3. C. The valve makes the fifth wheel easier to lock
  4. D. The trailer air-supply control closes automatically as air pressure falls

Correct answer: D. – The trailer air-supply control closes automatically as air pressure falls

Charge the trailer air system, shut off the engine, and reduce tank pressure by repeatedly applying and releasing the brake pedal. The trailer air-supply control should pop out or move to the emergency position within the manufacturer’s specified range, usually 20 to 45 psi. This confirms that the tractor protection valve responds to low pressure.

Source: North Dakota Commercial Driver License Manual (2025–2027) — § 7.4.1, “Additional Airbrake Checks”

Question 4

During an applied air-leakage test, what is the maximum permitted pressure loss for a combination vehicle?

  1. A. 2 psi per minute
  2. B. 2.5 psi per minute
  3. C. 3 psi per minute
  4. D. 4 psi per minute

Correct answer: D. – 4 psi per minute

North Dakota’s CDL manual sets the applied air-leakage limit for a combination vehicle at 4 psi in one minute after the initial pressure drop. The engine must be off, the parking brakes released, and at least 90 psi applied with the brake pedal. A greater loss requires the leaks to be repaired before driving.

Source: North Dakota Commercial Driver License Manual (2025–2027) — § 5.3.3, “Step 7 Final Airbrake Check”

Question 5

How should you verify that air reaches every trailer in a double or triple combination?

  1. A. At the last trailer, open the emergency and service shutoff valves one at a time and listen for escaping air
  2. B. Apply only the tractor parking brake and watch the gauges
  3. C. Accelerate sharply and check whether each trailer follows
  4. D. Observe the trailers in the mirrors while idling

Correct answer: A. – At the last trailer, open the emergency and service shutoff valves one at a time and listen for escaping air

Charge the supply lines and apply service-line pressure before going to the rear of the combination. Open the last trailer’s emergency-line valve and then its service-line valve, closing each after confirming that air escapes. Air must reach the rear of the combination for every trailer’s brakes to work.

Source: North Dakota Commercial Driver License Manual (2025–2027) — § 7.4.1, “Additional Airbrake Checks”

Question 6

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

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

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

On newer vehicles, the trailer air-supply control is a red, eight-sided knob. Push the knob in to open the tractor protection valve and supply air to the trailer system. Pulling it out stops the air supply and causes the trailer emergency brakes to apply.

Source: North Dakota Commercial Driver License Manual (2025–2027) — § 6.2.3, “Trailer Air Supply Control”

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