Combination Vehicles & Coupling

5 free sample questions of the 50 in this topic. The full set is in the app.

1. Question 1

   More than half of truck-driver deaths in accidents result from:

   • A.Truck rollovers
   • B.Rear-end collisions
   • C.Brake fires
   • D.Backing accidents
   Show answer & explanation

   Answer: A. Truck rollovers

   Rollovers kill more truck drivers than anything else — and fully loaded rigs are 10 times more likely to roll than empty ones.

   Source: California Commercial Driver Handbook (DL 650) — §6.1.1 — Rollover risks

2. Question 2

   The two main things that prevent rollover are:

   • A.Keeping cargo as close to the ground as possible, and driving slowly around turns
   • B.Wider tires and stiffer springs
   • C.Higher tire pressure and engine braking
   • D.Heavier loads and faster turns
   Show answer & explanation

   Answer: A. Keeping cargo as close to the ground as possible, and driving slowly around turns

   Low cargo, slow turns — and keep the load centered; a load leaning to one side makes rollover more likely.

   Source: California Commercial Driver Handbook (DL 650) — §6.1.1 — Rollover risks

3. Question 3

   Compared with an empty rig, a fully loaded rig is how much more likely to roll over?

   • A.10 times
   • B.2 times
   • C.Half as likely
   • D.Equally likely
   Show answer & explanation

   Answer: A. 10 times

   Loaded = higher center of gravity = 10× the rollover likelihood in an accident.

   Source: California Commercial Driver Handbook (DL 650) — §6.1.1 — Rollover risks

4. Question 4

   "Rearward amplification" means:

   • A.The crack-the-whip effect — sudden steering moves are amplified at the rear trailer
   • B.Engine torque multiplying in low gears
   • C.Brake pressure rising toward the rear axles
   • D.Trailer sway from wind only
   Show answer & explanation

   Answer: A. The crack-the-whip effect — sudden steering moves are amplified at the rear trailer

   The last trailer of triples can roll 3.5 times as easily as a 5-axle tractor-semitrailer — steer gently and smoothly when pulling trailers.

   Source: California Commercial Driver Handbook (DL 650) — §6.1.2 — Rearward amplification

5. Question 5

   A sudden steering movement while pulling a trailer can:

   • A.Tip the trailer over
   • B.Improve tracking
   • C.Engage the ABS
   • D.Disconnect the glad hands
   Show answer & explanation

   Answer: A. Tip the trailer over

   Rearward amplification turns your small jerk into the trailer's big swing — smooth inputs only.

   Source: California Commercial Driver Handbook (DL 650) — §6.1.2 — Steer gently

45 more Combination Vehicles & Coupling questions are in the app, along with explanations and flashcards for every one.

OnRoute is an independent study aid based on the federal CDL standards (49 CFR Part 383), the FMCSA Entry-Level Driver Training theory curriculum (49 CFR Part 380 Appendix A), and related Federal Motor Carrier Safety Regulations. It is not affiliated with, endorsed by, or sponsored by the FMCSA, AAMVA, or any state driver licensing agency. CDL knowledge tests are administered by your state, and state-specific requirements may vary — always consult your state's CDL manual.