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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 South Dakota doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The SD CDL doubles triples test covers the following sections of the South Dakota CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this SD CDL practice test now to prepare for the actual test! Important: Triple trailers are not legal in South Dakota.
1. When should you downshift automatic transmissions?
When you start to get drowsy.
When going down steep grades.
Watch your tachometer, and downshift when your engine reaches the top of the range.
When you want to go faster.
2. Which of the following is a common cause of truck fires?
loose fuel connections.
Short circuits due to loose connections.
Under-inflated tires and duals that touch.
All of the above.
3. When checking the lights before driving:
you should check them from inside the vehicle.
the engine must be running.
make sure the parking brake is not set.
you should turn off the engine.
4. On front tires, tread should be at least:
4/16 inch
4/32 inch
2/32 inch
1/16 inch
5. On dry pavement, the braking distance when travelling at 55 mph is about:
61 feet.
419 feet.
216 feet.
142 feet.
6. Doubles and triples:
have a lower chance of skidding.
can be turned suddently due to the low center of gravity.
can be stopped suddenly due to their weight.
can't be turned suddenly.
7. If you are caught in strong winds, you should:
speed up while keeping a strong grip on the steering wheel.
immediately take your foot off the accelerator.
keep a strong grip on the steering wheel and slow down or pull off the roadway.
None of the above.
8. If the low air pressure warning light comes on, you should:
set the parking brake.
continue to drive normally.
call for help.
stop immediately.
9. The earliest way to recognize that your trailer has started to skid is:
by checking your mirrors.
by hearing squeaking noises from the wheels.
by releasing the brakes.
by checking the jackknife sensor.
10. It's very important to distribute the cargo so it is:
as high up as possible.
as low as possible.
piled up.
in the centre of the load.
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SD 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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