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Doubles & Triples CDL Practice Test

The Doubles/Triples endorsement allows operation of vehicles pulling two or three trailers. Topics include coupling pintle hooks, converter dollies, glad hand connections for multiple trailers, managing rearward amplification across multiple articulation points, inspection sequence for additional units, and the rules for trailer order based on weight.

Why this test exists

Each additional articulation point multiplies rearward amplification. A driver pulling triples must steer earlier, brake sooner, and inspect twice as much equipment as a single-trailer driver.

How to study this section

Learn the correct trailer placement order by weight, the procedure for converting a single to a double, and the special inspection items unique to converter dollies and pintle hook assemblies.

60 practice questions

• Q1. The Doubles/Triples (T) endorsement is required when operating:
• Q2. A 'converter dolly' is:
• Q3. The heaviest trailer in a doubles or triples combination should be:
• Q4. Rearward amplification:
• Q5. The pintle hook is:
• Q6. Coupling a converter dolly to a second trailer involves:
• Q7. Safety chains on a converter dolly are required because:
• Q8. The pre-trip inspection of a doubles/triples combination must include:
• Q9. Air supply lines for the rear trailer pass through:
• Q10. When uncoupling triples, you should:
• Q11. Doubles and triples are most likely to roll over:
• Q12. When braking a doubles or triples combination, you should:
• Q13. Approximate maximum advisable highway speed when pulling triples is:
• Q14. Crosswinds affect doubles/triples by:
• Q15. Glad hand connections must be inspected on:
• Q16. When checking a converter dolly's brakes you should:
• Q17. A 'turntable' on a converter dolly:
• Q18. When backing doubles, drivers typically:
• Q19. The rear trailer in a triple can swing how much more than the tractor on a quick steering input?
• Q20. A safety pawl or 'jaw lock' on the fifth wheel of a converter dolly:
• Q21. A pre-trip air check on a triples combination should include:
• Q22. A common cause of separation between a tractor and trailing unit is:
• Q23. When the rear trailer of a double sways in a crosswind, you should:
• Q24. The order of trailers (besides weight) may also be set by:
• Q25. The total length of doubles or triples is regulated:
• Q26. A driver who must couple a converter dolly should first:
• Q27. When you couple to a second trailer using a converter dolly, the trailer brakes for the second trail…
• Q28. For triples, the air system must be:
• Q29. When approaching an exit ramp with triples, you should:
• Q30. A common safety chain configuration is:
• Q31. When parked overnight, you should:
• Q32. A driver of doubles/triples should keep a minimum following distance of:
• Q33. A converter dolly that drops its tongue when uncoupled can:
• Q34. When inspecting brake chambers on the rear trailers, the same standards apply as on the tractor:
• Q35. When swapping which trailer is in front, drivers should re-verify:
• Q36. When a triple combination encounters a steep grade, you should:
• Q37. A bobtail tractor going to pick up the first trailer should:
• Q38. The fifth wheel on a converter dolly:
• Q39. When uncoupling, the proper position for the trailer landing gear/dolly support is:
• Q40. A driver of a doubles combination noticing the rear trailer wandering on a straight road should:
• Q41. Where the converter dolly has a brake control of its own (parking spring brake), it should be:
• Q42. The 'air loss' tolerance with all units coupled is:
• Q43. When a trailer in a multi-trailer combo experiences a flat tire, the driver should:
• Q44. A driver should never attempt to:
• Q45. When pulling out from a stop sign with doubles, you should:
• Q46. The converter dolly tongue is:
• Q47. The single most common cause of separation in doubles/triples is:
• Q48. The pintle hook latch must be:
• Q49. When pulling triples in mountainous terrain, the most important driving principle is:
• Q50. You should never tow a trailer with:
• Q51. A 'lunette ring' is:
• Q52. When triples are not allowed on a route:
• Q53. A driver completing a triples trip should:
• Q54. A walkaround inspection of doubles/triples takes:
• Q55. A driver should suspect coupling failure if:
• Q56. When triples encounter a low overhead clearance:
• Q57. When the company changes how trailers must be ordered, the driver should:
• Q58. A skidding rear trailer can:
• Q59. Mirror checks for doubles/triples should be:
• Q60. Drivers of doubles/triples should be especially aware that:

State-specific resources

Each U.S. state administers the CDL knowledge test through its own DMV. The federal questions are the same; the test scheduling, fees, and identification requirements vary. Start with your state's overview:

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