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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 Tennessee doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The TN CDL doubles triples test covers the following sections of the Tennessee CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this TN CDL practice test now to prepare for the actual test!
1. ABS:
does not decrease your stopping distance.
helps you increase your following distance.
helps you increase your average speed.
improves your visibility at night.
2. The application pressure gauge:
shows how much air pressure is being applied to the brakes.
tells you how much pressure is in the air tanks.
stops the compressor from pumping air.
protects the tank and the rest of the system from too much pressure.
3. When you push in the red trailer air supply knob, this will:
open the emergency line shut-off valve at the rear of the last trailer.
supply air to the emergency supply lines.
disconnect the air lines from the trailer.
disconnect the electrical connector.
4. When coupling, you should:
make sure the sliding fifth-wheel is locked.
make sure the trailer wheels are not chocked.
make sure the trailer kingpin is bent.
be aware that wrong coupling and uncoupling can be very dangerous.
5. To prevent getting sleepy while driving, you should:
keep the cab warm.
drive alone whenever possible.
keep cool by opening the window.
close the vent.
6. Warnings on low bridges or underpasses:
are often posted, but sometimes they are not.
must be posted.
are always posted.
None of the above.
7. Rough acceleration can cause:
tire damage.
mechanical damage.
damage electrical and brake lines.
All of the above.
8. When approaching a double railroad track, you should:
remember that a train on one track may hide a train on the other track.
remember that trains may be more frequent.
expect to hear a train when it's approaching.
rely upon the presence of warning signals.
9. If your brakes fail on a steep mountain downgrade, you should:
slow down until your vehicle comes to a complete stop.
decide what to do as soon as you know your brakes do not work.
stay on the road and keep looking for the next available escape ramp.
set the parking brake and park in an open area.
10. The trailer hand valve should:
never be used to test the trailer brakes.
be used in driving.
never be used for parking.
All of the above.
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TN CDL Doubles Triples Test

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