Endorsement Practice Exam Questions

Ohio CDL Double/Triple Trailer Endorsement Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2025|2026 Q&A | Instant Download Pdf

• What is the biggest problem when driving a double or triple trailer?
• Backing up
• Passing other vehicles
• Maintaining stability and avoiding rollover
• Turning at intersections

The main hazard is the increased risk of rollover because doubles and triples are less stable than single trailers.

• Before coupling, which trailer should be connected first when pulling

triples? 1 / 4

• The lead trailer
• The rear trailer
• The first (converter dolly) trailer
• Any order is fine

You must couple the converter dolly to the first trailer before connecting the rear trailer to maintain control and proper alignment.

• When should you check that air flows to all trailers?
• Before starting the trip
• Only after the first stop
• Before every trip, after coupling
• Only when brakes fail

Always verify air flow after coupling to ensure all trailer brakes receive proper air pressure.

• When driving doubles, where should the heaviest trailer be placed?
• In the rear
• In the front, closest to the tractor
• In the middle
• It doesn’t matter

The heaviest trailer must be first to improve stability and prevent jackknife or rollover. 2 / 4

• The service air line is usually what color?
• Green
• Blue
• Red
• Yellow

The blue line is the service line that controls normal braking.

• What color is the emergency air line?
• Blue
• Red
• Yellow
• Green

The red line supplies air to fill the trailer tanks and control emergency brakes.

• What happens if the service line breaks or becomes disconnected while

driving?

• Nothing happens
• The trailer service brakes lock
• The trailer brakes may apply due to loss of air pressure
• The trailer detaches 3 / 4

Loss of air pressure can cause the trailer brakes to engage automatically for safety.

• What should you do before unlocking the converter dolly fifth wheel?
• Apply the service brakes
• Accelerate slowly
• Chock the wheels of the second trailer
• Disconnect the air lines

Chocking prevents trailer movement when unlocking the dolly.

• When inspecting doubles or triples, what should you check for between

trailers?

• Extra hoses
• Properly connected air and electrical lines
• Cargo seals
• Matching license plates

Always verify all lines are secure and not tangled.

10. Converter dollies are equipped with:

• Hydraulic brakes
• Air brakes
• Electric brakes
• / 4