What should you do to check that the trailer is locked into the tractor?

To ensure that the trailer is securely locked into the tractor, gently pulling the tractor forward while maintaining pressure on the brakes is an effective method. This action allows you to feel if the coupling mechanism on the fifth wheel is engaged properly. When you pull forward, if the coupling is not secured, there will be noticeable movement that can indicate a problem. Moreover, maintaining pressure on the brakes during this process ensures that you can stop immediately if there is any sign of disengagement, providing an additional layer of safety.

This method is practical because it combines a visual inspection with a physical test, allowing the driver to confirm the connection without putting the vehicle in motion at full speed. Engaging the brakes while attempting this test protects the driver from rolling away unintentionally, ensuring a safer check of the connection between the tractor and the trailer.