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CDL Quiz 13

1. How should you check that the spring brakes come on when the air pressure in the system drops below a certain level?
Park on level ground, chock the wheels, release the parking brake when you have enough air pressure, shut the engine off, and repeatedly press and release the brake pedal.
Park on a slight incline, drain off air pressure, set the parking brakes, and check for movement.
Park on level ground, wait for normal air pressure, release the parking brake, move the truck forward slowly, and apply the brakes firmly using the brake pedal.

2. The air compressor stops pumping air at ___ psi.
100
125
150

3. How can you test the low pressure warning signal?
Shut off the engine and see if the air pressure leaks down.
While the engine is running, step on and off the brake pedal.
Shut off the engine with enough air pressure, turn on the electrical power, and step on and off the brake pedal until the low air pressure warning signal comes on.

4. You know that your brakes are fading when
You have to press the brake pedal harder to control speed on a downgrade.
Pressure on the brake pedal is released and speed increases.
The brake feels spongy when pressure is applied.

5. The S-cam forces the brake shoes away from one another and presses them against the inside of the brake drum. It is called the S-cam because
It is shaped like the letter “N.”
It is shaped like the letter “Z.”
It is shaped like the letter “S.”

6. What are the other names for the service air line?
Straight line and control line
Curved line and signal line
Control line and signal line

7. Why should you make sure that the fifth wheel plate is greased as required?
To prevent steering problems
To ensure good electrical connections
To reduce heat and noise

8. Here are two things that a driver can do to prevent a rollover: Keep the cargo as close to the ground as possible, and
Keep the fifth wheel’s free play as tight as possible.
Make sure that the brakes are properly adjusted.
Go slowly around turns.

9. Air and electrical lines from the tractor to the trailer should be
Secured but with enough slack for turns.
Pulled tight with very little slack.
Resting on the frame of the tractor.

10. You should not use the trailer hand valve while driving because
Of the danger of making the trailer skid.
It won’t work as well as the foot brake.
You should use the parking brake.

11. When you drive a set of doubles, which shut-off valve must be closed in the last trailer?
Middle section
Back
Front

12. What gear should the tractor engine be in after you uncouple the trailer and are inspecting the trailer supports?
High reverse
Neutral
Low reverse

13. The service line
Carries air to the cab of the rig to cool it.
Carries air to the parking brake to control the trailer brakes.
Carries air to a relay valve that allows the trailer brakes to be applied quickly.

14. Almost half of all truck driver deaths are the result of
Following too closely.
Speed.
Rollovers.

15. You are coupling a tractor to a semi-trailer. You have connected the air lines. Before backing under the trailer, you should
Take sure that the trailer brakes are off.
Pull ahead to test the glad hands connections.
Supply air to the trailer system and then pull out the air supply knob.

16. Which statement best explains the “crack-the-whip” effect?
When you make a quick lane change or sudden movement of your steering wheel, the tractor tends to rock and sway. The velocity of the rearmost trailer forces the tractor to roll over before the trailer.
Your trailer is half full, and the cargo is loaded in the front of the trailer. When you make a sudden movement of your steering wheel, cargo will tend to forcefully slide to the back of the trailer, forcing the trailer to roll over.
When you make a quick lane change or sudden movement of your steering wheel, the rear trailer tends to swing out. The force of the rear trailer becomes amplified, causing it to roll over (rearward amplification).

17. Under good driving conditions, you should leave at least one second of space between your vehicle and the vehicle ahead for every ___ feet of your vehicle’s length.
30
20
10

18. When connecting the glad hands, press the two seals together with the couplers at what angle to each other?
180 degrees
45 degrees
90 degrees

19. Why should you lock the tractor glad hands (or dummy couplers) to each other when you are not towing a trailer?
The connected brake circuit becomes a backup air tank.
If you don’t, you will never build system pressure.
It will keep dirt and water out of the lines.

20. Which of these vehicles off-tracks the most?
A 5-axle tractor towing a 42-foot trailer
A 5-axle tractor towing a 52-foot trailer
A 5-axle tractor towing a 45-foot trailer