Save Time and Get a Pass Guarantee! LIMITED-TIME OFFER: Get CDL PREMIUM Now and SAVE $64! Upgrade To Premium


View instructions
Drivers who want to drive combination vehicles must pass the combination vehicles test. The District of Columbia CDL combination test consists of 20 questions, and you'll need at least 16 correct answers to pass (80%). The test covers the combination vehicles section of the District of Columbia CDL Manual. Take this practice test now to prepare for the actual DC CDL combination test!
1. Tests have shown that trucks with a high center of gravity are more likely to tip over, therefore you should:
distribute the cargo so the majority of the weight is on the steering axle.
put the lightest parts of the cargo under the heaviest parts.
distribute the cargo as low as possible.
All of the above.
2. During your inspection, you should look into the fifth-wheel gap and check that the _________ are fully closed around the kingpin.
mounting bolts
lug nuts
locking jaws
couplings (U-joints)
3. Tar in the road pavement rising to the road surface in very hot weather:
does not affect the road surface or driving conditions.
is very sticky and will slow down your vehicle.
might get in your engine.
causes the road to become very slippery.
4. To stop a trailer skid, you should:
countersteer to get traction back.
use the trailer hand brake to straighten out the rig.
release the brakes to get traction back.
use the brakes to slow down.
5. Which of the following will NOT help you prevent rollover?
Keeping the cargo as close to the ground as possible.
Driving slowly around turns.
Using the controlled braking method.
All of the above.
6. When backing with a trailer, you should:
check your mirrors on both sides frequently.
look at your line of travel before you begin backing.
make pull-ups to re-position your vehicle as needed.
All of the above.
7. When you inspect the coupling, make sure there is ______ between the upper and lower fifth wheel.
about 1 inch
enough space
about 1/2 inch
no space
8. If your ABS is not working:
the drive wheels will begin to spin, and you should take your foot off the accelerator.
you still have normal brake functions, and should drive and brake as you always have.
you should immediately bring your vehicle to a complete stop.
it will slow your truck to a halt and force you to pull over.
9. In combination vehicles with air brakes, the trailer air supply control should pop out when the air pressure falls within the range of:
50 to 75 psi
100 to 120 psi
20 to 45 psi
10 to 20 psi
10. A truck tractor with _________ requires the shortest stopping distance.
an empty trailer
a fully loaded trailer
Weight has no impact on stopping distance.
a lightly loaded trailer
Page 1 of 2
Next page  
Rate This Free Test
4.6 out of 5
based on 182 votes

DC CDL Combination 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%
Share This Online CDL Test