CDL Vehicle Combination Practice Test

What gear should the tractor engine be in after you uncouple the trailer and are inspecting the trailer supports?

1. Drive

2. Reverse

3. Neutral

4. Park

The correct answer is: Neutral

When inspecting the trailer supports after uncoupling the trailer, it is essential for the tractor engine to be in neutral. This is because being in neutral allows the engine to run without the vehicle moving, ensuring that the operator can safely focus on the inspection without the risk of the tractor inadvertently moving forward or backward. Having the tractor in neutral also reduces the chances of unintended gear engagement, which could lead to accidents or damage to the vehicle or trailer during the inspection. This practice is a vital safety measure, as it ensures that the vehicle is stable and secure while performing necessary inspections, such as checking the trailer's landing gear or supports. Using drive or reverse would pose risks since these gears could result in the tractor moving unexpectedly. Similarly, while putting the vehicle in park could seem safe, it may not be necessary when the vehicle is at a standstill and the operator is simply inspecting the trailer supports. Thus, neutral is the most appropriate and safest gear for maintaining control during the inspection process.