Knowledge Practice Exam Questions

CDL Doubles/Triples (T) Written Knowledge Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• When driving a double or triple trailer combination, what is the most

important thing to remember about backing?

• Always back quickly to avoid accidents
• Back slowly and make small steering adjustments
• Use only mirrors on the left side
• Always have a co-driver
• Back slowly and make small steering adjustments

Backing doubles and triples is difficult; slow, controlled movements reduce the risk of jackknifing.

• Which trailer in a double/triple combination is most likely to sway?
• The first trailer 1 / 4

• The last trailer
• The middle trailer
• All trailers sway equally
• The last trailer

The last trailer has the most freedom to move independently and is most prone to sway.

• How should you adjust your driving when hauling doubles/triples in

windy conditions?

• Drive faster to reduce time in the wind
• Slow down and increase following distance
• Keep the same speed as normal
• Only use cruise control
• Slow down and increase following distance

High winds can push trailers around; reducing speed and leaving extra space improves control.

• What is the main cause of trailer jackknife in doubles or triples?
• Excessive speed when turning or braking
• Poor tire inflation
• Driving on flat roads
• Following too closely
• Excessive speed when turning or braking

Sharp maneuvers or hard braking can cause the trailer to swing out, leading to a jackknife. 2 / 4

• How often should you check your mirrors when driving a

doubles/triples combination?

• Once every 10 minutes
• Continuously, at least every 5-8 seconds
• Only when changing lanes
• Only at stop signs
• Continuously, at least every 5-8 seconds

Frequent mirror checks help monitor trailer position and surrounding traffic.

• When coupling a trailer, what is important to check first?
• Brake adjustment
• Fifth wheel locking
• Tire pressure
• Air lines
• Fifth wheel locking

A properly locked fifth wheel ensures the trailer stays attached to the tractor.

• Which trailer is most likely to “crack the whip” during sudden

acceleration or deceleration?

• The first trailer
• The second or last trailer
• The middle trailer
• The trailer closest to the tractor 3 / 4

• The second or last trailer

The rear trailers experience amplified motion from the tractor’s acceleration or braking.

• When driving doubles/triples down a steep hill, what is the best

braking technique?

• Continuous light braking
• Apply brakes fully once at the bottom
• Use engine braking and apply brakes in intervals
• Rely on service brakes only
• Use engine braking and apply brakes in intervals

This prevents brake overheating and maintains control of the long combination vehicle.

• Which factor increases the chance of trailer swing in a doubles/triples

combination?

• Driving slowly
• Lightly loaded trailers
• Properly inflated tires
• Balanced loads
• Lightly loaded trailers

Empty or lightly loaded trailers are easier to move and sway more in turns or wind.

• When inspecting a doubles/triples combination, you notice

loose or missing trailer mounting bolts. What should you do?

• / 4