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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 North Dakota doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The ND CDL doubles triples test covers the following sections of the North Dakota CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this ND CDL practice test now to prepare for the actual test! Important: Triple trailers are not legal in North Dakota.
1. On front tires, tread should be at least:
1/16 inch
4/32 inch
4/16 inch
2/32 inch
2. Which of the following is most likely to roll over?
The rear trailer of a triple
The front trailer of a double
The middle trailer of a triple
The rear trailer of a double
3. In a dual air brake system, if one air system is very low on pressure:
you should pump the brakes to restore pressure.
you should drive and brake as you always have.
either the front or rear brakes will not be operating fully.
the effect won't be noticeable for the first 50 miles.
4. To prevent rollover, you should do all of the following except:
keep the load centered on your rig.
drive slowly around turns.
avoid quick lane changes.
put the lightest parts of the cargo under the heaviest parts.
5. 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.
rely upon the presence of warning signals.
expect to hear a train when it's approaching.
6. Before operating the vehicle, the driver should:
rely on the last vehicle inspection and skip the pre-trip inspection.
should not review the vehicle inspection report and immediately try to find any vehicle defects.
review the last vehicle inspection report.
None of the above.
7. With an engine fire, you should:
turn the engine off as soon as possible.
open the hood as soon as possible.
not shoot foam from the vehicle’s underside.
All of the above.
8. Longer combination vehicles have the tendency to swing wide on turns. This is called:
9. What factors can cause brakes to fade?
Slippery surfaces and shaded areas.
Gravel and tar.
Dirt roads and in unpaved yards.
Excessive heat and brakes out of adjustment.
10. If you must stop on a one-way or divided highway, you should place warning devices _______ toward the approaching traffic.
5, 50 and 500 feet
3, 15 and 45 feet
5, 25 and 50 feet
10, 100 and 200 feet
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ND CDL Doubles Triples Test

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