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Double Triple Test | District Of Columbia 2026 #2 Page 3 of 3
Train for FREE with our District Of Columbia CDL double triple practice test online. The official exam test consists of several obligatory parts, with all of them checking your knowledge of different blocks of road rules. If you need to obtain a DC CDL double triple license in 2026, practice as much as possible. Free sample tests published on our website will help you check and improve your knowledge and boost your grades. Please bear in mind that DMV requirements may vary from state to state.
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15 . What must be on an air tank in an air-braked vehicle?
An oxidizer
All air tanks on air-braked vehicles must have one-way check valves located between the air compressor and the first reservoir. This prevents air from flowing out in the event of a leak.
16 . If your truck or trailer catches fire, you should:
Park in an open area.
If there is a fire in your vehicle, the first thing you need to do is leave the road and stop. Park in an open area away from anything that could catch fire, such as plants or other vehicles. Do not pull into a service station.
17 . Coupling can be tested by a driver:
Releasing the orange lever in the cab.
It is essential to safety that a driver inspects coupling before starting a trip. Trailer coupling on a double or triple combination can be tested by pulling against the pin of the second semi-trailer.
18 . When coupling a double or triple, which trailer should be attached last?
It doesn’t matter.
When coupling a double or triple combination, the rearmost trailer should be the final trailer attached.
19 . When it is difficult for others to see your vehicle, such as at dawn or dusk, you can help other drivers by:
Waving an arm out the window.
At times when visibility is low, you should turn your headlights on to the low beam setting. If you are having a difficult time seeing others, they are probably having a difficult time seeing you.
20 . When passing another vehicle, you should:
Wait for the other driver to signal that it is safe to do so.
