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Combination Vehicles Practice Question 55

Required for Class ACombination Vehicles · Question 55

A trailer with sliding tandems lets you:

• AAdjust trailer length
• BMove the rear axles forward or backward to redistribute weight on the tractor and trailer axles
• CIncrease trailer height
• DSwitch from air to spring suspension

Correct answer: B. Move the rear axles forward or backward to redistribute weight on the tractor and trailer axles

Why: Sliding tandems redistribute load between the tractor drives and trailer tandems to comply with axle weight limits at 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

• Q12. Rearward amplification means:
• Q25. The 'safety latch' on the fifth wheel locking lever:
• Q38. A heavy trailer pushing on the tractor going downhill is called:
• Q51. When you must back into a busy area, you should:
• Q1. A combination vehicle is generally defined as:

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.