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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 Maryland doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The MD CDL doubles triples test covers the following sections of the Maryland CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this MD CDL practice test now to prepare for the actual test!
1. The trailer hand valve should be used:
to check that the trailer emergency brakes are on.
to test the trailer brakes.
to check that the trailer is locked onto the tractor.
to check that the fire extinguisher is charged.
2. To reduce the chance of rollover, you should:
put the lightest parts of the cargo under the heaviest parts.
place the cargo as high as possible inside the trailer.
distributed the cargo as low as possible inside the trailer.
None of the above.
3. During freezing weather, which area is most likely to be slippery after it rains?
Roads that look wet.
Shaded areas.
All of the above.
4. To know how much space you should keep in front of you when driving at speeds below 40 mph, one good rule says you need at least ______ for each ______ of vehicle length.
2 seconds; 10 feet
3 seconds; 50 feet
1 second; 5 feet
1 second; 10 feet
5. What factors can cause brakes to fade?
Gravel and tar.
Excessive heat and brakes out of adjustment.
Dirt roads and in unpaved yards.
Slippery surfaces and shaded areas.
6. When going down a steep downgrade, you should primarily brake using:
the parking brake.
the braking effect of the engine.
the service brakes.
the emergency brake.
7. If there is a fire and you are not sure what to use to put it out, you should:
use water.
wait for firefighters.
use a fire extinguisher.
use dry powder.
8. A red triangle with an orange center means:
The vehicle is hauling hazardous materials
Law enforcement vehicle
Liquid tanker
Slow-moving vehicle
9. If your ABS malfunctions:
you still have normal brake functions.
you should immediately come to a complete stop.
the service brake will not work.
the parking brakes will not work.
10. Pre-trip inspections are:
required only for trips of more than 50 miles.
required by law
required only for trips of more than 100 miles.
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MD CDL Doubles Triples Test

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