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Combination Vehicles Practice Question 10

Required for Class ACombination Vehicles · Question 10

A high-coupled trailer (kingpin riding above the jaws) can result in:

• ASmooth operation
• BTrailer separation while driving
• CBetter fuel economy
• DLonger brake life

Correct answer: B. Trailer separation while driving

Why: If the kingpin rides over the jaws instead of locking into them, the trailer can separate from the tractor under load. The visual jaw-lock check exists to catch this.

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

• Q3. The kingpin is part of the:
• Q17. Cargo loaded too far to one side will:
• Q30. Stopping distance for a fully loaded combination vehicle is:
• Q43. When parking a combination vehicle, you should:
• Q56. When sliding the fifth wheel forward, the load on the steering axle:

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.