Combination Vehicles Practice Test | Oklahoma 2025 #1 Page 3 of 3
Train for FREE online with our Oklahoma 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 OK combination license in 2025, 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.
15 . If the emergency air line loses pressure:
The tractor protection valve keeps air in the trailer's braking system should the trailer break away or develop a leak. A loss of air pressure in the emergency line will cause the tractor protection valve to open and the emergency trailer brakes to activate.
16 . When driving while pulling trailers, you should:
You should always steer gently and smoothly while pulling a trailer. Making sudden steering moves could cause the trailer to tip over.
17 . Rearward amplification refers to:
Vehicles with trailers are vulnerable to rollover due to the "crack-the-whip" effect, which is caused by rearward amplification.
18 . What does an Anti-Lock Braking System (ABS) do?
An Anti-Lock Braking System (ABS) helps prevent wheel lockup during hard braking. If ABS detects impending lockup, it reduces braking pressure to a safe level.
19 . Fully-loaded rigs:
Fully-loaded rigs are more vulnerable to rolling over than empty rigs because the weight of the cargo gives the vehicles higher centers of gravity.
20 . Keeping cargo low can:
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.
See the exact questions that will be on the 2025 Oklahoma DMV exam.
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