CDL COMBINATION VEHICLES EXAM
After coupling, how much space should be between the upper and lower 5th wheel? -
ANSWER-None
Describe what the service line is for. - ANSWER-The service line ( called the control line )
carries air, which is controlled by the foot brake or the trailer hand brake.
Depending on how hard you press the foot brake or hand valve, the pressure in the service
line will similarily change.
Describe what trailer air supply control does. - ANSWER-You push it in to supply the trailer
with air, and pull it out to shut the air off and put on the trailer emergency brakes.
The valve will pop out ( closing the tractor protection valve ) when the air pressure drops
into the range of 20-45 psi.
Fully loaded rigs are ___ times more likely to roll over in a crash than empty rigs. -
ANSWER-10
How can you test that air flows to all trailers? - ANSWER-Go to the rear of the rig. Open the
emergency line shut-off valve at the rear of the last trailer.
You should hear air escaping, showing the entire system is charged.
How can you test the tractor-protection valve? - ANSWER-Push in the "air supply" knob,
step on and off the brake pedal several times to reduce the air pressure in the tanks.
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 ( also called tractor protection valve )
How can you test the trailer service brakes? - ANSWER-At normal air pressure, release
the parking brakes. Move the vehicle forward slowly, and apply trailer hand brake.
How do you check for a secure connection? - ANSWER-Pull tractor gently while the trailer
brakes are still locked to check that the trailer is locked on the trcator.
How do you know if the trailer is at proper height? - ANSWER-The trailer should be low
enough that it is raised slightly by the tractor when the tractor is backed under it.
How much following distance should you have driving 50 mph? - ANSWER-At least 1
second for every 10 feet of your vehicle plus an additional second.
, How much follwoing distance should you have? - ANSWER-At leats 1 second for every 10
feet of vehicle length under 40 mph.
In any combination rig, allow lots of ___ distance and look far ahead. - ANSWER-Following
Large combination vehicles take longer to stop when they are... - ANSWER-Empty
Rollovers happen when you turn too___ - ANSWER-Fast
TREU OR FALSE:
More than half of truck driver deaths in crashes are the result of truck rollovers. -
ANSWER-True
Trucks with trailers have a dangerous... - ANSWER-crack the whip effect
TRUE OR FALSE:
ABS makes it possible to drive faster more safely. - ANSWER-False
TRUE OR FALSE:
ABS will increase your stopping distance. - ANSWER-False
TRUE OR FALSE:
All new trailers and converter dollies are requirered to have anti-lock brakes. - ANSWER-
True
TRUE OR FALSE:
Blue is used for the service line and red for the emergency. - ANSWER-True
TRUE OR FALSE:
If you must back on a curved path, back to the drivers side so you can see. - ANSWER-
True
TRUE OR FALSE:
If your ABS malfunctions, you will loose your brakes - ANSWER-False
TRUE OR FALSE:
Keeping cargo low is even more important in combination vehicles than in straight trucks. -
ANSWER-True
After coupling, how much space should be between the upper and lower 5th wheel? -
ANSWER-None
Describe what the service line is for. - ANSWER-The service line ( called the control line )
carries air, which is controlled by the foot brake or the trailer hand brake.
Depending on how hard you press the foot brake or hand valve, the pressure in the service
line will similarily change.
Describe what trailer air supply control does. - ANSWER-You push it in to supply the trailer
with air, and pull it out to shut the air off and put on the trailer emergency brakes.
The valve will pop out ( closing the tractor protection valve ) when the air pressure drops
into the range of 20-45 psi.
Fully loaded rigs are ___ times more likely to roll over in a crash than empty rigs. -
ANSWER-10
How can you test that air flows to all trailers? - ANSWER-Go to the rear of the rig. Open the
emergency line shut-off valve at the rear of the last trailer.
You should hear air escaping, showing the entire system is charged.
How can you test the tractor-protection valve? - ANSWER-Push in the "air supply" knob,
step on and off the brake pedal several times to reduce the air pressure in the tanks.
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 ( also called tractor protection valve )
How can you test the trailer service brakes? - ANSWER-At normal air pressure, release
the parking brakes. Move the vehicle forward slowly, and apply trailer hand brake.
How do you check for a secure connection? - ANSWER-Pull tractor gently while the trailer
brakes are still locked to check that the trailer is locked on the trcator.
How do you know if the trailer is at proper height? - ANSWER-The trailer should be low
enough that it is raised slightly by the tractor when the tractor is backed under it.
How much following distance should you have driving 50 mph? - ANSWER-At least 1
second for every 10 feet of your vehicle plus an additional second.
, How much follwoing distance should you have? - ANSWER-At leats 1 second for every 10
feet of vehicle length under 40 mph.
In any combination rig, allow lots of ___ distance and look far ahead. - ANSWER-Following
Large combination vehicles take longer to stop when they are... - ANSWER-Empty
Rollovers happen when you turn too___ - ANSWER-Fast
TREU OR FALSE:
More than half of truck driver deaths in crashes are the result of truck rollovers. -
ANSWER-True
Trucks with trailers have a dangerous... - ANSWER-crack the whip effect
TRUE OR FALSE:
ABS makes it possible to drive faster more safely. - ANSWER-False
TRUE OR FALSE:
ABS will increase your stopping distance. - ANSWER-False
TRUE OR FALSE:
All new trailers and converter dollies are requirered to have anti-lock brakes. - ANSWER-
True
TRUE OR FALSE:
Blue is used for the service line and red for the emergency. - ANSWER-True
TRUE OR FALSE:
If you must back on a curved path, back to the drivers side so you can see. - ANSWER-
True
TRUE OR FALSE:
If your ABS malfunctions, you will loose your brakes - ANSWER-False
TRUE OR FALSE:
Keeping cargo low is even more important in combination vehicles than in straight trucks. -
ANSWER-True
