After coupling, how do you verify the converter dolly's pintle hook and the trailer connections are secure?

A doubles or triples coupling has several connection points that must each be verified. The pintle hook on the trailer ahead must be fully closed and latched around the dolly's eye, not merely resting on it, and the safety chains must be secured. At the fifth wheel, there must be no space between the upper and lower fifth wheel or between the trailer and the fifth wheel, and the locking jaws must be closed around the kingpin. The driver should also connect and check the air and electric lines. A gentle pull test against the locked connection confirms it will hold. A missed connection can let a trailer separate at speed — a catastrophic failure.