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Combination Vehicles Practice Question 56

Required for Class ACombination Vehicles · Question 56

When sliding the fifth wheel forward, the load on the steering axle:

• ADecreases
• BIncreases
• CStays the same
• DBecomes negative

Correct answer: B. Increases

Why: Sliding the fifth wheel forward shifts more trailer weight onto the tractor's steering axle. Use this to balance gross axle weights at the scales.

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

• Q43. When parking a combination vehicle, you should:
• Q57. A pressure test of trailer air lines should include:
• Q6. Visual inspection of the fifth wheel coupling must confirm:
• Q19. Cargo loaded too far rearward can:
• Q32. When climbing a long uphill grade with a heavy load, 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.