FREE CDL Combination Vehicles Practice Test Online | District Of Columbia 2024
Train for FREE online with our District Of Columbia CDL combination vehicle test. 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 combination license in 2021, 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 for issuing a combination license may vary from state to state.
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1 . When lightly loaded, combination vehicles:
Should be loaded with most of the weight in the rear of the trailer.
When a combination vehicle is lightly loaded, it may have poor traction. It is very easy for wheels to lock up on lightly-loaded vehicles when they are being stopped.
2 . Compared to other commercial motor vehicles, combination vehicles need more space on the road because they are longer and they:
Swerve more often.
Combination vehicles need more space on the road than other commercial vehicles because they are longer and need more space to turn and stop. It is especially important to properly manage space when you are operating a combination vehicle.
3 . To prevent a rollover, a driver should:
Turn quickly.
Rollovers can happen when a combination vehicle is turned too quickly. To help prevent the risk of rollover, it is important to keep the vehicle's center of gravity low by loading cargo as close to the ground as possible.
4 . When driving a trailer with ABS, you should:
Try to not brakes as often as you would when driving a vehicle without ABS.
When driving a tractor-trailer combination equipped with an Anti-Lock Braking System (ABS), you should brake in the same manner that you would if operating a vehicle without ABS.
5 . If colors are being used to distinguish glad hands, which color is used for service lines?
Blue
When trailer air lines are color-coded, the service lines are generally blue and the emergency lines are generally red.
6 . To help prevent rollovers, you should:
Keep the load on one side of the trailer.
To lower the risk of a rollover, load your cargo as closely to the ground as possible. To further reduce this risk, take curves and corners slowly.
7 . If a trailer's spring brakes do not release when you push the tractor air supply control, you should:
Drive normally without checking anything.
