JJ Keller Entry Level Driver Training CDL Practice Test 2025 – Comprehensive All-in-One Guide to Exam Success!

Before uncoupling a tractor-trailer, backing slightly to ease pressure on the jaws is essential to ensure that the fifth wheel locks are released safely. When the trailer is under pressure, it can be difficult to completely disengage the locking mechanism of the fifth wheel. If the trailer is still bearing weight, it could lead to difficulties when attempting to pull the tractor away, potentially causing damage or injury. By pulling back slightly, you relieve this pressure, allowing the fifth wheel jaws to open easily and ensure a smoother uncoupling process.

The other options focus on procedures that, while important, are not as immediately critical to the actual uncoupling operation. For instance, checking that both trailers are locked or performing a final check of the load are essential for safety and security but are not specifically related to the mechanics of uncoupling. Switching off all lights serves a purpose in indicating the vehicle is stationary but does not address the needs of the uncoupling process itself.