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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 Washington doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The WA CDL doubles triples test covers the following sections of the Washington CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this WA 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.
2. With a dual air brake system:
each system shares the same lines and hoses.
each system shares air tanks.
each system has its own air tanks, hoses and lines.
3. If a load is 10 feet long, the minimum number of tie-downs required is:
4. Air tanks usually hold enough compressed air to allow the brakes to be used _________ even if the compressor stops working.
several times
for one stop
for one day
5. On any upgrade, _________ – the more you will have to use lower gears to climb hills or mountains.
the longer the grade
the steeper the grade
All of the above.
6. If your ABS malfunctions:
you should immediately come to a complete stop.
you still have normal brake functions.
the service brake will not work.
7. Which of these describes the proper braking technique when driving on a long and steep downgrade?
Release the brakes until your speed is 5 mph above your safe speed, then apply the brakes. When your speed has decreased to your safe speed, repeat the previous steps.
Apply the brakes. When your speed has been reduced to 5 mph below your safe speed, release the brakes. When your speed has increased to your safe speed, repeat the previous steps.
Apply the brakes until your speed has been reduced to 5 mph, then release the brakes. When your speed has increased to your safe speed, repeat the previous steps.
8. If you doubt you have enough space to pass under a bridge, you should:
turn on your headlights.
drive faster.
go slowly.
9. If your brakes fail on a steep mountain downgrade, you should:
use an escape ramp if it is available.
leave the road immediately.
go right if the shoulder is clear.
10. In vehicles with air brakes, the two markings on a front brake limiting valve are:
high and low.
left and right.
normal and slippery.
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WA CDL Doubles Triples Test

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