CDL - SECTION 6: COMBINATION VEHICLES/
QUESTIONS WITH CERTIFIED ANSWERS.
Why should you NOT use the trailer hand valve while driving? - Answer: The
danger of making the trailer skid.
Describe what the trailer air supply control does. - Answer: Push in -- Supply air to
trailer; Push out -- Shut air off and put on trailer emergency brakes
Describe what the service line is for. - Answer: Carries air, which is controlled by
the foot brake or the trailer hand brake.
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, What is the emergency air line for? - Answer: Supplies air to the trailer air tanks;
Controls the emergency brakes on combination vehicles.
Why should you use chocks when parking a trailer without spring brakes? -
Answer: To keep the trailer from moving.
Where are the shut-off valves? - Answer: Back of trailer.
What might happen if the trailer is too high when you try to couple? - Answer: It
may not couple correctly.
What two things are important to prevent rollover? - Answer: Keep cargo as close
to the ground as possible and drive slowly around turns.
When you turn suddenly while pulling doubles, which trailer is most likely to turn
over? - Answer: The rear trailer is twice as likely to turn over.
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QUESTIONS WITH CERTIFIED ANSWERS.
Why should you NOT use the trailer hand valve while driving? - Answer: The
danger of making the trailer skid.
Describe what the trailer air supply control does. - Answer: Push in -- Supply air to
trailer; Push out -- Shut air off and put on trailer emergency brakes
Describe what the service line is for. - Answer: Carries air, which is controlled by
the foot brake or the trailer hand brake.
Page 1 of 5
, What is the emergency air line for? - Answer: Supplies air to the trailer air tanks;
Controls the emergency brakes on combination vehicles.
Why should you use chocks when parking a trailer without spring brakes? -
Answer: To keep the trailer from moving.
Where are the shut-off valves? - Answer: Back of trailer.
What might happen if the trailer is too high when you try to couple? - Answer: It
may not couple correctly.
What two things are important to prevent rollover? - Answer: Keep cargo as close
to the ground as possible and drive slowly around turns.
When you turn suddenly while pulling doubles, which trailer is most likely to turn
over? - Answer: The rear trailer is twice as likely to turn over.
Page 2 of 5
