When is a trailer considered to be at the right height for backing under it?

A trailer is considered to be at the right height for backing under it when the trailer is lifted slightly by the tractor. This positioning ensures that the fifth wheel of the tractor can easily connect with the kingpin of the trailer. When the trailer is lifted, it allows for an efficient alignment as the tractor approaches, making it less likely for misalignment or damage to occur during the coupling process. Proper height also aids in achieving the correct angle needed to properly engage the coupler and ensures secure attachment for safe driving.

In contrast, if the trailer is parallel to the ground, it may not be at the optimal height for coupling, as this alignment can make attachment more difficult. If the trailer is not touching the ground, it could imply that it is too high, which complicates the backing process and increases the risk of miss coupling. Similarly, if the tractor is level with the trailer, it might not provide that slight lift needed for proper engagement and could lead to challenges in the backing maneuver. Understanding the right height for backing under a trailer is crucial for safe and effective operation of combination vehicles.