Home › Practice › Combination Vehicles › Question 5

Combination Vehicles Practice Question 5

Required for Class ACombination Vehicles · Question 5

After backing under the trailer, you should:

• ADisconnect the air immediately
• BTest the connection by pulling forward gently against the locked kingpin
• CDrive away immediately
• DDrop the landing gear

Correct answer: B. Test the connection by pulling forward gently against the locked kingpin

Why: After feeling the locking jaws engage, set the tractor parking brake, shift to a low forward gear, and gently tug against the kingpin to verify a secure connection before getting out.

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

• Q38. A heavy trailer pushing on the tractor going downhill is called:
• Q51. When you must back into a busy area, you should:
• Q64. The forward visibility of a tractor's hood and mirrors creates a blind area in front of th…
• Q14. The first sign of a tractor drive-wheel skid is often:
• Q27. A converter dolly is used to:

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.