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Combination Vehicles Practice Question 8

Required for Class ACombination Vehicles · Question 8

When uncoupling, after lowering the landing gear and disconnecting glad hands you should:

• ADrive forward immediately
• BPull the fifth-wheel release handle, then slowly drive the tractor out from under the trailer
• CRelease the parking brake first
• DLower the trailer further

Correct answer: B. Pull the fifth-wheel release handle, then slowly drive the tractor out from under the trailer

Why: Set the trailer brakes, lower landing gear so it bears trailer weight, disconnect glad hands and electrical, pull release handle, then ease the tractor out from under the trailer.

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

• Q4. When coupling, you should approach the trailer:
• Q18. Cargo loaded too far forward can:
• Q31. Trailer ABS sensors are typically located at:
• Q44. Glad hand color coding is required because:
• Q57. A pressure test of trailer air lines should include:

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.