What should be ensured during a visual check of coupling?

Ensuring there is no space between the upper and lower fifth wheel is critical for a safe and secure coupling between the tractor and the trailer. The fifth wheel is the mechanism that connects the truck to the trailer, and any gap can indicate improper coupling or alignment. This gap could lead to a dangerous situation, such as the trailer disengaging while the vehicle is in motion or causing unstable handling. Therefore, inspecting this connection helps confirm that the coupling is properly engaged, allowing for safe operation during transit.

The other factors, while important for overall vehicle safety and operational integrity, are not as directly related to the immediate coupling mechanism as the presence of a space in the fifth wheel connection. Ensuring the trailer is aligned, all lights are operational, and the converter dolly is secured are all excellent practices but do not directly address the critical aspect of the connection between the tractor and trailer that the absence of space at the fifth wheel represents.