What indicates the correct trailer height before connecting a converter dolly?

When connecting a converter dolly to a trailer, the proper height of the trailer is indicated by a slight raising of the trailer. This occurs because the converter dolly typically has a fifth wheel that is set higher than the kingpin height of the trailer. As you back the dolly under the trailer, the pivot point of the dolly raises the trailer slightly, ensuring that the connection to the fifth wheel is effective and secure.

If the trailer is at the correct height when the dolly is positioned correctly, it allows for a proper and safe coupling. This slight elevation helps to align the kingpin with the fifth wheel and ensures that there is adequate clearance for the connection to be made. It also prepares the trailer for dynamic forces that occur during driving, ensuring stability and safety while the vehicle is in motion.

In contrast, if the trailer were to remain at the same height, be lowered, or disconnect entirely, it would not indicate a proper connection, potentially leading to unsafe conditions while driving. Therefore, observing that the trailer is raised slightly upon the connection is the correct indicator of proper trailer height before securing the dolly.