JJ Keller Entry Level Driver Training for CDL (Commercial Driver’s License) Practice Test

When preparing to couple a rear trailer to a converter dolly, the height of the trailer is important for ensuring a proper connection. The correct answer, which indicates that the trailer should be slightly lower than the center of the fifth wheel, is essential because it allows for an effective coupling.

When the trailer is slightly lower than the fifth wheel, it ensures that as the dolly is backed under the trailer, the fifth wheel can rise slightly as it engages with the kingpin. This also helps to prevent any potential misalignment that could occur if the trailer were level or higher than the fifth wheel, which could complicate the hooking process or create a situation where the connection is not secure.

This approach also accounts for vertical movement that may occur from the weight of the trailer as it is being coupled. Ensuring the trailer is positioned lower than the fifth wheel mitigates risks and promotes a smoother and more reliable coupling process.