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Combination Vehicles Practice Question 14

Required for Class ACombination Vehicles · Question 14

The first sign of a tractor drive-wheel skid is often:

• AEngine stall
• BThe tractor begins to rotate around the coupling
• CTrailer lights flicker
• DBrake warning

Correct answer: B. The tractor begins to rotate around the coupling

Why: When drive wheels lose traction (often from over-acceleration or hard braking on slick roads), the tractor begins to rotate. Recover by releasing the brake or accelerator and steering into the skid.

How this question fits the Combination test

Articulated vehicles fail in unique ways: trailer swing under braking, rearward amplification under steering, and jackknife under loss of traction. Combination Vehicle knowledge is required for any Class A applicant under 49 CFR 383.111.

Study technique for this topic

Walk through the coupling sequence verbally until it's second nature. Know the safe-rolling rearward amplification factor, the difference between trailer service brakes and parking brakes, and what creates the conditions for a tractor jackknife.

Related Combination practice questions

• Q1. A combination vehicle is generally defined as:
• Q15. To prevent rollover with a high center of gravity, you should:
• Q28. When uncoupling a trailer, the order generally includes:
• Q41. The most common cause of trailer wheel lockup in non-ABS trailers is:
• Q54. When a passenger car cuts in front of you, you should:

Continue your CDL preparation

The Combination Vehicles portion of the CDL knowledge exam covers more than this single question. Use this site's full Combination Vehicles bank to drill every topic, then test yourself with one of our state-specific practice sets to confirm you are ready for the actual DMV exam in your state. Always check your state's CDL handbook for any local addenda before the test day.

If you are still building your overall CDL foundation, start with the General Knowledge bank — every CDL applicant must pass it — and then work outward to the endorsements you plan to add.