CDL Combination Practice Test
CDL Combination Practice Test
Questions and Answers 2024
You're hooking up a tractor to a semi-trailer and have backed up but are not under it.
What should you do before backing under the trailer? - Hook up the emergency and
service air lines.
After pushing in the trailer supply valve, you should not move the tractor
until air system is? - At normal pressure
There are two things you can do to prevent a rollover. They are: Keep the cargo as
close to the ground as possible, and: - Reduce speed before entering turns.
With the engine off and the brakes released, a combination vehicle air brake system
shouldn't leak more than how many psi in one minute? - 3 psi
The fifth wheel locking lever isn't locked after the jaws close around the kingpin. This
means that: - The coupling is not correct and should be corrected before driving the
coupled unit.
You cross the air lines when hooking up to an old trailer. What will happen? - If the
trailer has no spring brakes, you could drive away, but you wouldn't have trailer brakes.
How far should you crank up the front trailer supports after coupling a semi-trailer? -
Fully raised with the crank handle secured
Air brake equipped trailers made before 1975 - Usually do not have spring brakes
The hand valve should be used to park a combination vehicle: - Never
Air lines on a combination vehicle are often colored to keep them from getting mixed up.
The emergency line is ____ - Red
How do you supply air to the air tank on the trailer? - By pushing in the trailer air supply
valve.
In normal driving, some drivers use the hand valve before applying the brake pedal to
prevent trailer skids. Which of these statements is true? - It should never be done.
CDL Combination Practice Test
CDL Combination Practice Test
Questions and Answers 2024
You're hooking up a tractor to a semi-trailer and have backed up but are not under it.
What should you do before backing under the trailer? - Hook up the emergency and
service air lines.
After pushing in the trailer supply valve, you should not move the tractor
until air system is? - At normal pressure
There are two things you can do to prevent a rollover. They are: Keep the cargo as
close to the ground as possible, and: - Reduce speed before entering turns.
With the engine off and the brakes released, a combination vehicle air brake system
shouldn't leak more than how many psi in one minute? - 3 psi
The fifth wheel locking lever isn't locked after the jaws close around the kingpin. This
means that: - The coupling is not correct and should be corrected before driving the
coupled unit.
You cross the air lines when hooking up to an old trailer. What will happen? - If the
trailer has no spring brakes, you could drive away, but you wouldn't have trailer brakes.
How far should you crank up the front trailer supports after coupling a semi-trailer? -
Fully raised with the crank handle secured
Air brake equipped trailers made before 1975 - Usually do not have spring brakes
The hand valve should be used to park a combination vehicle: - Never
Air lines on a combination vehicle are often colored to keep them from getting mixed up.
The emergency line is ____ - Red
How do you supply air to the air tank on the trailer? - By pushing in the trailer air supply
valve.
In normal driving, some drivers use the hand valve before applying the brake pedal to
prevent trailer skids. Which of these statements is true? - It should never be done.
CDL Combination Practice Test
