Kentucky CDL Combination Practice Test (KY) 2

5 out of 5 (71 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Prepare thoroughly for your Commercial Driver's License (CDL) with our Kentucky CDL combination practice test. This well-crafted test includes 20 multiple-choice questions on critical topics such as inspection procedures, safe driving practices, air brake systems, and more. To pass, you'll need to correctly answer at least 16 questions, ensuring a solid grasp of essential knowledge. Our KY practice permit test is designed to boost your confidence and prepare you for the actual permit test. You'll find questions that cover a range of key areas, including the dangers of jackknifing. This occurs when the trailer swings out of alignment with the tractor, creating a hazardous situation. Through smooth braking and careful handling, you can learn to avoid this danger, contributing to safer driving practices. Each question on our permit practice test comes with immediate feedback and detailed explanations. This feature helps you understand why an answer is correct or incorrect, enhancing your learning experience. By comprehending the reasoning behind each answer, you can better retain information and apply it to real-world scenarios. Our Kentucky DMV practice test also incorporates real-life driving situations. These scenarios help you not only prepare for the written permit test but also develop skills for safe driving on KY's diverse roads. Whether navigating the bustling streets of Louisville, the winding roads through the Appalachian Mountains, or the flatlands of Western Kentucky, our test prepares you for the unique driving conditions found across the state. For those who benefit from visual aids, many questions on our KY combination CDL test include images to help you better understand the context. This approach is especially useful for visual learners, making complex topics more accessible. By using our CDL combination practice test, you'll gain the knowledge and confidence needed to pass your permit test and drive safely on Kentucky's roads. Start today and take the first step toward becoming a skilled and responsible CDL driver.
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Sample Kentucky Combination Test Questions

Question 1

If the trailer wheels lock and the trailer begins to skid, what should you do first?

  1. A Accelerate sharply
  2. B Steer rapidly in the opposite direction
  3. C Apply the trailer hand valve harder
  4. D Release the brakes to restore traction

Correct answer: D – Release the brakes to restore traction

Locked trailer wheels lose traction and can swing sideways, creating a jackknife. Release the brakes so the wheels can begin rolling and regain traction. Do not use the trailer hand valve to straighten the combination because additional trailer braking continues the condition that caused the skid.

Source: Kentucky Commercial Driver’s License Manual — § 6.1.5, “Prevent Trailer Skids”

Question 2

Before backing a tractor fully under a trailer during coupling, the air system must be:

  1. A Between 60 and 80 psi
  2. B Reduced to half of normal pressure
  3. C At normal operating pressure
  4. D Completely drained

Correct answer: C – At normal operating pressure

After connecting the service and emergency lines, supply air to the trailer and wait until pressure reaches its normal operating level. Check the system for crossed lines, major leakage, and proper trailer-brake operation. The trailer brakes are then locked before the tractor is backed fully under the trailer.

Source: Kentucky Commercial Driver’s License Manual — § 6.4.1, “Coupling Tractor-Semitrailers,” Steps 7–10

Question 3

A proper coupling inspection includes looking into the back of the fifth wheel to verify that the jaws surround the kingpin shank. True or false?

  1. A True
  2. B False

Correct answer: A – True

After coupling, secure the vehicle and visually inspect the connection. Look into the back of the fifth wheel and confirm that the locking jaws are closed around the shank of the kingpin, not around its head. Also verify that there is no gap between the fifth-wheel surfaces and that the locking lever and safety latch are secured.

Source: Kentucky Commercial Driver’s License Manual — § 6.4.1, “Coupling Tractor-Semitrailers,” Step 13

Question 4

If you discover that the trailer service air line has separated while driving, what should you do?

  1. A Increase speed to maintain air pressure
  2. B Continue driving until the emergency brakes apply
  3. C Use only the trailer hand valve
  4. D Stop safely and have the line repaired before continuing

Correct answer: D – Stop safely and have the line repaired before continuing

A separated service line removes the normal air signal used to apply the trailer service brakes. The Kentucky CDL manual explains that the leak may not become obvious until the brakes are applied; if pressure then falls far enough, the trailer emergency brakes may engage. Federal safety rules prohibit continued operation of an unsafe commercial vehicle, so stop safely and correct the defect.

Source: Kentucky Commercial Driver’s License Manual — §§ 6.2.4 and 6.2.8, “Trailer Air-lines” and “Trailer Service, Parking and Emergency Brakes”, 49 CFR § 396.7 — Unsafe operations forbidden

Question 5

The trailer service line separates, but the emergency line remains connected. What is likely to happen immediately?

  1. A The tractor’s emergency brakes apply
  2. B The combination stops at once
  3. C The trailer tank immediately empties through the service line
  4. D There may be no obvious effect until the brakes are applied

Correct answer: D – There may be no obvious effect until the brakes are applied

The service line signals the relay valves to apply the trailer service brakes. If it separates while the emergency supply line remains intact, an immediate emergency-brake application is not expected. The driver may first notice the problem when applying the brakes; a major service-line leak can then lower system pressure quickly enough to activate the trailer emergency brakes.

Source: Kentucky Commercial Driver’s License Manual — §§ 6.2.4 and 6.2.8, “Trailer Air-lines” and “Trailer Service, Parking and Emergency Brakes”

Question 6

Before driving away with a coupled tractor-semitrailer, where should the trailer landing gear be positioned?

  1. A One-third raised, with the crank secured
  2. B Halfway raised, with the crank secured
  3. C Three-quarters raised, with the crank secured
  4. D Fully raised, with the crank secured

Correct answer: D – Fully raised, with the crank secured

Raise the landing gear completely before moving the combination and secure the crank handle in its keeper. Landing gear left partly down can catch on railroad tracks or other objects. The driver should also verify adequate clearance between the landing gear and tractor frame and between the tractor tires and trailer nose.

Source: Kentucky Commercial Driver’s License Manual — § 6.4.1, “Coupling Tractor-Semitrailers,” Step 15

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