Inspecting Doubles and Triples — CDL Doubles Triples Practice Test

This CDL Doubles Triples Inspecting Doubles and Triples practice set has 30 practice questions based on the official exam materials, each with an instant explanation. You need 80% on the real CDL Doubles Triples knowledge test to pass.

Sample questions

Three questions from the Inspecting Doubles and Triples bank with the correct answer and an explanation. The practice quiz above draws 30 questions at random from the same bank.

1. Which inspection procedure should you use to inspect a combination vehicle pulling doubles or triples?

   • The seven-step inspection procedure from Section 2 — Correct answer
   • A shorter three-step procedure made just for doubles
   • No inspection is needed when pulling more than one trailer
   • Only a check of the lead trailer's tires

   Explanation: Use the seven-step inspection procedure described in Section 2 to inspect your combination vehicle; there are more things to inspect on a combination vehicle than on a single vehicle. English term: seven-step inspection procedure (七步检查程序 / procedimiento de inspección de siete pasos).

   Handbook: Section 7: Doubles and Triples — Inspecting Combination Vehicles

2. How do the doubles/triples coupling-system checks relate to the Section 2, Step 5 walkaround inspection?

   • You do them in addition to the Step 5 walkaround checks — Correct answer
   • They replace the Step 5 walkaround checks
   • You skip Step 5 entirely when pulling doubles
   • They are done only at the end of the trip, not before

   Explanation: Do the doubles/triples checks in addition to those already listed in Section 2, Step 5: Do Walkaround Inspection — they are extra checks, not a replacement. English term: walkaround inspection (绕车检查 / inspección caminando alrededor).

   Handbook: Section 7: Doubles and Triples — Additional Walkaround Checks

3. When checking the lower fifth wheel, what must be true about how it is mounted?

   • Securely mounted to the frame — Correct answer
   • Loosely bolted so it can pivot freely
   • Mounted to the trailer's axle, not the frame
   • Welded shut so it cannot move at all

   Explanation: Check the lower fifth wheel: it must be securely mounted to the frame. English term: fifth wheel (第五轮 / quinta rueda).

   Handbook: Section 7: Doubles and Triples — Lower Fifth Wheel