CDL doubles and triples practice test

1. When checking the fifth wheel during an inspection, what condition regarding the space between the upper and lower sections is required?

1. There should be visible space between them
2. There should be no visible space between them
3. The upper section should be raised
4. The lower section should be lowered

2. When coupling twin trailers, where should the more heavily loaded semitrailer be positioned for the safest handling?

1. In the first position behind the tractor
2. In the rear position behind the lighter trailer
3. On the converter dolly between the two trailers
4. Either position, as weight distribution does not affect handling

3. How do you verify that the air brakes on the second trailer are functioning correctly after coupling?

1. Push the air supply knob in and check for air at the rear of the second trailer by opening the emergency line shut-off
2. Listen for the sound of air escaping from the service line shut-off at the front of the first trailer
3. Check the pressure gauge on the tractor dashboard to ensure it reads above 100 psi
4. Visually inspect the slack adjusters to confirm they are correctly adjusted

4. During the tractor protection valve test, within what pressure range should the control close or move to the emergency position?

1. Between 20 and 45 psi.
2. Between 10 and 30 psi.
3. Between 45 and 60 psi.
4. Between 60 and 80 psi.

5. When inspecting the coupling system of a combination vehicle, how should the locking jaws be positioned relative to the kingpin?

1. Around the head of the kingpin
2. Around the shank of the kingpin
3. Around the glide plate
4. Around the release arm

6. Why must drivers of doubles and triples allow more following distance than other commercial vehicles?

1. Because they cannot be turned or stopped suddenly
2. Because their engines take longer to warm up
3. Because they have smaller blind spots
4. Because their cargo is always lighter

7. If the second trailer does not have spring brakes, what procedure sets the trailer emergency brakes during coupling?

1. Drive the tractor close, connect the emergency line, charge the air tank, then disconnect the emergency line
2. Leave the emergency line connected and rely solely on the tractor's parking brakes
3. Disconnect the service line immediately after connecting the emergency line
4. Chock the wheels before connecting any air lines to the trailer

8. During a walkaround inspection of double or triple trailers, what is the required position for the shut-off valves at the rear of the front trailers?

1. Closed
2. Open
3. Half-open
4. Removed

9. Why is it critical to ensure air reaches the back of the trailer combination during the air flow check?

1. To ensure all brakes work properly.
2. To prevent the tractor protection valve from popping out.
3. To allow the trailer handbrake to engage automatically.
4. To reduce the air pressure in the tanks to the manufacturer's specification.

10. How should a driver steer when pulling trailers to prevent rollover?

1. Steer gently
2. Steer sharply to correct drift quickly
3. Use rapid steering inputs to maintain balance
4. Avoid steering until the vehicle is fully stopped

11. What is the correct position for the shut-off valve at the rear of the last trailer in a combination vehicle?

1. Open
2. Closed
3. Loosened
4. Disconnected

12. According to the handbook, why are doubles and triples more likely to turn over than other combination vehicles?

1. Because of the "crack-the-whip" effect
2. Because they have heavier cargo capacities
3. Because their tires wear out faster
4. Because they require more frequent air brake adjustments

13. What is the correct height adjustment for the rear trailer when coupling the converter dolly?

1. It must be slightly lower than the center of the fifth wheel so the trailer is raised slightly when the dolly is pushed under
2. It must be exactly level with the center of the fifth wheel to ensure a flat connection
3. It must be significantly higher than the fifth wheel to allow easy entry of the dolly tongue
4. Height does not matter as long as the locking jaws close on the kingpin

14. What is the required safety feature for converter dollies built on or after March 1, 1998?

1. They are required to have antilock brakes
2. They must have a blue lamp on the right side
3. They must be equipped with automatic leveling systems
4. They require a secondary hydraulic brake line