NYC CDL COMBINATION VEHICLES TEST
After coupling, how much space should be between the upper and lower fifth wheel? -
ANSWER-None
Describe what the service line is for - ANSWER-carries air, which is controlled by the foot
brake or hand valve
Describe what the trailer air supply control does. - ANSWER-push it in to supply the trailer
with air, pull it out to shut the air off and put on the emergency brakes
How can you test that air flows to all trailers: - ANSWER-listen - open the emergency line
shut off valve, you should hear air escaping, then close it. open the service line valve to
make sure air goes through all trailers, if you do not hear air going to all trailers check the
shut off valves
How can you test the tractor protection valve? - ANSWER-Charge trailer air brake system.
Shut off engine. Step on & off brake pedal. Control should pop out at 20-45 psi. (6.5.2)
How can you test the trailer emergency brakes? - ANSWER-Charge the trailer air brake
system and check that the trailer rolls freely. Then stop and pull out the trailer air supply
control.(6.5.2)
How can you test the trailer service brakes? - ANSWER-Release parking brakes, move
forward slowly & apply trailer brakes with hand control (6.5.2)
How do you know if your trailer is equipped with antilock brakes? - ANSWER-Look under
the vehicle for the ECU and wheel speed sensor wires coming from the back of the brakes
To drive you need to raise the landing gear only until it just lifts off the pavement. True or
False? - ANSWER-False
What is off tracking? - ANSWER-the rear wheels follow a different path than the front
wheels
What is the emergency air line for? - ANSWER-supplies air to the trailer air tanks, and
controls the emergency brakes on a combination vehicle
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 your cargo low and
centered
What type of trailers can get stuck on railroad-highway crossings? - ANSWER-Low slung
units (lowboy, car carrier, moving van, possum-belly livestock trailer).
After coupling, how much space should be between the upper and lower fifth wheel? -
ANSWER-None
Describe what the service line is for - ANSWER-carries air, which is controlled by the foot
brake or hand valve
Describe what the trailer air supply control does. - ANSWER-push it in to supply the trailer
with air, pull it out to shut the air off and put on the emergency brakes
How can you test that air flows to all trailers: - ANSWER-listen - open the emergency line
shut off valve, you should hear air escaping, then close it. open the service line valve to
make sure air goes through all trailers, if you do not hear air going to all trailers check the
shut off valves
How can you test the tractor protection valve? - ANSWER-Charge trailer air brake system.
Shut off engine. Step on & off brake pedal. Control should pop out at 20-45 psi. (6.5.2)
How can you test the trailer emergency brakes? - ANSWER-Charge the trailer air brake
system and check that the trailer rolls freely. Then stop and pull out the trailer air supply
control.(6.5.2)
How can you test the trailer service brakes? - ANSWER-Release parking brakes, move
forward slowly & apply trailer brakes with hand control (6.5.2)
How do you know if your trailer is equipped with antilock brakes? - ANSWER-Look under
the vehicle for the ECU and wheel speed sensor wires coming from the back of the brakes
To drive you need to raise the landing gear only until it just lifts off the pavement. True or
False? - ANSWER-False
What is off tracking? - ANSWER-the rear wheels follow a different path than the front
wheels
What is the emergency air line for? - ANSWER-supplies air to the trailer air tanks, and
controls the emergency brakes on a combination vehicle
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 your cargo low and
centered
What type of trailers can get stuck on railroad-highway crossings? - ANSWER-Low slung
units (lowboy, car carrier, moving van, possum-belly livestock trailer).
