When Should You Lower the Landing Gear When Uncoupling a Truck-Tractor From a Semi-Trailer?

When uncoupling a truck-tractor from a semi-trailer,When should you lower the landing gear?

a) After disconnecting the air lines
b) Before lowering the trailer supports
c) After completing the pre-trip inspection
d) Before chocking the wheels

Final answer:

Lower the landing gear before lowering the trailer supports to ensure the trailer is securely supported when uncoupling a truck-tractor from a semi-trailer.

Explanation:

When uncoupling a truck-tractor from a semi-trailer, you should lower the landing gear before lowering the trailer supports, which would be option b). Lowering the landing gear ensures that the trailer is securely supported once it is disconnected from the truck-tractor. It is important to perform this step before disconnecting the air lines or chocking the wheels to prevent the trailer from moving or tilting dangerously.