Final answer:
To ease pressure on the fifth wheel locking jaws before uncoupling a tractor-trailer, you can park on a slight decline, chock the trailer brakes, and lock the trailer brakes and back up gently.
Step-by-step explanation:
To ease pressure on the fifth wheel locking jaws before uncoupling a tractor-trailer, there are several steps you can take.
A. Park on a slight decline when possible: This allows gravity to help relieve pressure on the locking jaws.
B. Chock the trailer brakes: Placing wheel chocks in front of and behind the trailer tires can prevent the trailer from rolling while uncoupling, reducing pressure on the locking jaws.
C. Lock the trailer brakes and back up gently: Locking the trailer brakes and then gently backing up can help relieve pressure on the locking jaws.
Therefore, the correct answer is D. All of the above.