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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. If there is a fire in your vehicle, do NOT:
park in an open area.
pull into a service station.
park away from buildings and other vehicles.
notify emergency services.
2. Alcohol:
does not affect judgement.
improves reaction time.
impairs depth perception.
improves muscle coordination.
3. "Bobtail" tractors are:
tractors with a tank.
heavily loaded trailers.
tractors without semitrailers.
tractors with two trailers.
4. You hear a loud "bang" which sounds like a tire blowout. You should:
assume you have a tire failure.
inspect your tires with your mirrors.
keep driving as normal.
check the tires at the next stop.
5. Under a pressurized system, the radiator cap:
should never be hot.
should be removed when the coolant is hot.
should always be cool.
should never be removed until the system has cooled.
6. Air tanks usually hold enough compressed air to allow the brakes to be used _________ even if the compressor stops working.
several times
for one day
for one stop
for 3 days
7. At dawn, dusk, in rain or snow, to make yourself easier to see you should:
use the high beams.
use the parking lights.
use the emergency flashers.
use the low beams.
8. If you are caught in strong winds, you should:
keep a strong grip on the steering wheel and slow down or pull off the roadway.
immediately take your foot off the accelerator.
speed up while keeping a strong grip on the steering wheel.
None of the above.
9. The trailer hand valve should be used:
to test the trailer brakes.
to check that the trailer is locked onto the tractor.
to check that the fire extinguisher is charged.
to check that the trailer emergency brakes are on.
10. Air brakes use ________ to make the brakes work.
compressed gas cylinders
compressed oil
compressed gases
compressed air
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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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