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Safely pulling double and triple trailers requires knowledge and skill. If you want to pull double or triple trailers, you must add the Doubles/Triples (T) endorsement to your Class A CDL. The District of Columbia doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The DC CDL doubles triples test covers the following sections of the District of Columbia CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this DC CDL practice test now to prepare for the actual test!
1. Which of the following is not proper tie-down equipment:
Bungee cords
2. If the fifth-wheel locking lever is not locked after the jaws close around the kingpin:
cargo is properly blocked.
the parking brakes are on and your vehicle is safe to drive.
the coupling is not right and you should not drive until you get it fixed.
the parking brakes are on and the wheels are chocked.
3. Before driving a vehicle with a dual brake brake system, the driver should:
pump the brake pedal 10 times to build pressure.
wait at least 10 minutes before driving.
wait at least 5 minutes before driving.
allow time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems.
4. The space under a heavily loaded vehicle can be very small. This can cause problems:
on dirt roads.
when crossing railroad tracks.
on unpaved yards.
All of the above.
5. To reduce the chance of rollover, you should:
put the lightest parts of the cargo under the heaviest parts.
distributed the cargo as low as possible inside the trailer.
place the cargo as high as possible inside the trailer.
None of the above.
6. The best way to recognize that your trailer has started to skid is:
by seeing it in your mirrors.
by feeling the brakes come on.
by recognizing tire failure.
by opening the window and feeling the front of the mirror.
7. The safety valve is usually set to open at:
150 psi.
100 psi.
200 psi.
75 psi.
8. Which of the following is NOT correct? Anti-lock brakes:
require drivers to apply the brakes as hard as they can without locking the wheels.
give drivers more control over the vehicle during braking.
help drivers avoid skids caused by over braking.
help drivers avoid wheel lock up.
9. When backing, it is best to:
try to back in the direction of the drift.
use a helper whenever possible.
use only the passenger's side mirror.
back toward the passenger's side when possible.
10. Hanging meat in a refrigerated truck:
will not affect safe driving ability.
can be a very unstable load.
creates a low center of gravity.
should never be transported.
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DC CDL Doubles Triples Test

Number of questions: 20
Correct answers to pass:16
Passing score:80%
Number of questions: 20
Correct answers to pass:16
Passing score:80%
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