Control & OperationQuestion 72 of 120
You are uncoupling a trailer in a yard. Which sequence is correct?
a.Pull the fifth wheel release, then lower the landing gear, then chock the wheels
b.Disconnect the air lines first, then pull forward, then lower the landing gear
c.Ease pressure on the locking jaws, chock the trailer wheels, lower the landing gear until it takes the weight, disconnect the air and electrical lines and secure them, pull the release handle, and pull the tractor partially clear before checking
d.Lower the landing gear, pull completely clear, then disconnect the lines
Explanation
Taking pressure off the jaws, securing the trailer, setting the landing gear, and only then releasing and easing forward keeps the trailer supported at every step. The other sequences release the coupling or the lines before the trailer is supported, which can drop the trailer or tear the air lines apart.
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