After backing the converter dolly under the rear trailer and raising the landing gear slightly off the ground, how should you confirm the coupling is actually secure before connecting the remaining lines?

Question

Accepted Answer

Test the coupling by pulling against the pin of the second semitrailer, then make a visual check that there is no gap between the upper and lower fifth wheel and that the locking jaws are closed on the kingpin

Answer

Drive forward at normal speed for several hundred feet; if the trailer doesn't detach, the coupling is secure

Answer

Check only that the landing gear is fully raised; that alone proves the fifth wheel jaws have closed around the kingpin

Answer

Open the shut-off valves at the rear of the first trailer before testing the coupling, since air pressure alone confirms a mechanical lock