CDL - General Knowledge, Combinations, Air Brakes Exam:
100% Expert Verified Study Guide Real Testing 2026|2027
Questions Detailed Answers and Instructor Note for A+
Guaranteed Pass
Gross Combination Weight Rating (GCWR) - Answers -The value specified by the manufacturer
as the loaded weight of a COMBINATION vehicle is?
Stay on shoulder until your vehicle has come to a stop - Answers -To avoid an accident you
moved to the shoulder. The shoulder is clear, you should:
With the tractor frame under the trailer - Answers -Where should the tractor be when you
inspect the landing gear after uncoupling the trailer?
10 - Answers -While driving behind another vehicle, under good conditions, you should allow at
least one second between your vehicle and the vehicle ahead each ___ feet of your vehicle
length.
Go slow around turns - Answers -There are two things that a driver can do to prevent a rollover.
They are 1. keep the cargo as close to the ground as possible and 2.
1|Page
,3 - Answers -The air brakes leakage rate for a combination vehicle (engine off, brakes off) should
not be more than ___ psi per minute.
Turn wide as you complete the turn - Answers -If you cannot complete your turn without
entering another traffic lane you should:
Easier to turn over - Answers -The higher the center of gravity of your truck, the:
Nothing is likely to happen until you try to apply the brakes. - Answers -If the service line comes
apart while you are driving a combination vehicle, but the emergency line stays together, what
will happen right away?
Service and emergency air lines from the vehicle to the trailer. - Answers -Glad hands are usually
connecting which of these?
If the trailer has no spring brakes, you could drive away, but you wouldn't have trailer brakes. -
Answers -A driver crosses the air lines when hooking up to an old trailer. What will happen?
To test the trailer brakes - Answers -The hand valve should be used:
2|Page
,Back valve - Answers -When driving a set of doubles, it is necessary to close which shut-off valve
in the last trailer:
Trailer will be lifted slightly when the tractor backs under it. - Answers -You are about to back
your trailer under a semitrailer. The trailer is at the right height when the:
Emergency trailer brakes to come on. - Answers -Your emergency air line breaks or gets pulled
apart while you are driving. The loss of pressure will cause the:
Check air line connection. - Answers -If the spring brakes are not released when you pushed the
trailer air supply valve you should:
Are not required to have spring brakes - Answers -Air brake equipped trailer made before 1975:
Keep the cargo as close to the ground as possible - Answers -There are two things that a driver
can do to prevent a rollover: They are 1. go slow around turns and 2.
Supply air to the trailer system, then pull out the air supply knob - Answers -After connecting
the air lines but before backing under the trailer you should:
The shank - Answers -Which part of the kingpin should the locking jaw close around?
3|Page
, None - Answers -How much space should be allowed between the upper and lower fifth wheel
after coupling?
At normal pressure - Answers -You have pushed the trailer air supply valve. You should not back
a tractor under a trailer until the whole air system is:
Supply air to the trailer system, then pull out the air supply knob - Answers -You are coupling a
tractor to the semitrailer; you have connected the airlines. Before backing under the trailer, you
should:
The emergency and service lines - Answers -You are coupling a tractor to a semitrailer and have
backed up, but are not under it. What should you hook up before backing under?
Fully loaded - Answers -Tractor with a ___ trailer requires the shortest amount of stopping
distance.
Low gear - Answers -After you have coupled the trailer you should raise the landing gear by
using:
Pushing out the trailer air supply valve - Answers -You supply air to the trailer tanks by:
4|Page
100% Expert Verified Study Guide Real Testing 2026|2027
Questions Detailed Answers and Instructor Note for A+
Guaranteed Pass
Gross Combination Weight Rating (GCWR) - Answers -The value specified by the manufacturer
as the loaded weight of a COMBINATION vehicle is?
Stay on shoulder until your vehicle has come to a stop - Answers -To avoid an accident you
moved to the shoulder. The shoulder is clear, you should:
With the tractor frame under the trailer - Answers -Where should the tractor be when you
inspect the landing gear after uncoupling the trailer?
10 - Answers -While driving behind another vehicle, under good conditions, you should allow at
least one second between your vehicle and the vehicle ahead each ___ feet of your vehicle
length.
Go slow around turns - Answers -There are two things that a driver can do to prevent a rollover.
They are 1. keep the cargo as close to the ground as possible and 2.
1|Page
,3 - Answers -The air brakes leakage rate for a combination vehicle (engine off, brakes off) should
not be more than ___ psi per minute.
Turn wide as you complete the turn - Answers -If you cannot complete your turn without
entering another traffic lane you should:
Easier to turn over - Answers -The higher the center of gravity of your truck, the:
Nothing is likely to happen until you try to apply the brakes. - Answers -If the service line comes
apart while you are driving a combination vehicle, but the emergency line stays together, what
will happen right away?
Service and emergency air lines from the vehicle to the trailer. - Answers -Glad hands are usually
connecting which of these?
If the trailer has no spring brakes, you could drive away, but you wouldn't have trailer brakes. -
Answers -A driver crosses the air lines when hooking up to an old trailer. What will happen?
To test the trailer brakes - Answers -The hand valve should be used:
2|Page
,Back valve - Answers -When driving a set of doubles, it is necessary to close which shut-off valve
in the last trailer:
Trailer will be lifted slightly when the tractor backs under it. - Answers -You are about to back
your trailer under a semitrailer. The trailer is at the right height when the:
Emergency trailer brakes to come on. - Answers -Your emergency air line breaks or gets pulled
apart while you are driving. The loss of pressure will cause the:
Check air line connection. - Answers -If the spring brakes are not released when you pushed the
trailer air supply valve you should:
Are not required to have spring brakes - Answers -Air brake equipped trailer made before 1975:
Keep the cargo as close to the ground as possible - Answers -There are two things that a driver
can do to prevent a rollover: They are 1. go slow around turns and 2.
Supply air to the trailer system, then pull out the air supply knob - Answers -After connecting
the air lines but before backing under the trailer you should:
The shank - Answers -Which part of the kingpin should the locking jaw close around?
3|Page
, None - Answers -How much space should be allowed between the upper and lower fifth wheel
after coupling?
At normal pressure - Answers -You have pushed the trailer air supply valve. You should not back
a tractor under a trailer until the whole air system is:
Supply air to the trailer system, then pull out the air supply knob - Answers -You are coupling a
tractor to the semitrailer; you have connected the airlines. Before backing under the trailer, you
should:
The emergency and service lines - Answers -You are coupling a tractor to a semitrailer and have
backed up, but are not under it. What should you hook up before backing under?
Fully loaded - Answers -Tractor with a ___ trailer requires the shortest amount of stopping
distance.
Low gear - Answers -After you have coupled the trailer you should raise the landing gear by
using:
Pushing out the trailer air supply valve - Answers -You supply air to the trailer tanks by:
4|Page
