Combination Vehicles Practice Test | South Carolina 2026 #1 Page 2 of 3
Train for FREE online with our South Carolina 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 SC combination 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 for issuing a combination license may vary from state to state.
8 . When should the trailer hand valve be used?
The trailer hand valve, also called the trolley valve or Johnson bar, is used to work the trailer brakes. It should be used only to test the brakes. Using it while a vehicle is in motion could cause a skid.
9 . One way to prevent a rollover is to:
A rollover is more likely if cargo is unevenly loaded in a rig. To help prevent a dangerous rollover, it is important to keep a load as centered on the rig as possible.
10 . In a vehicle equipped with an automatic tractor protection valve, the valve will pop out when:
In vehicles equipped with an automatic tractor protection valve, the valve will pop out if air pressure drops to a level between 20 and 45 psi. When the valve pops out, the protection valve will close, stopping the flow of air.
11 . What is another name for the service line?
The trailer service air line may also be referred to as the control line or signal line.
12 . Push in the trailer air supply control to:
Push in the trailer air supply control to supply the trailer with air. Pull out the trailer air supply control to turn off the air supply and activate the emergency brakes.
13 . When driving a trailer with ABS, you should:
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.
14 . What is the Johnson bar?
The trailer hand valve, also called the trolley valve or Johnson bar, is used to work the trailer brakes. It should be used only to test the brakes. Using it while a vehicle is in motion could cause a skid.
See the exact questions that will be on the 2026 South Carolina DMV exam.
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