What is the next step after locking the kingpin into the fifth wheel?

Locking the kingpin into the fifth wheel is a critical step in securing the trailer to your tractor. The next appropriate action is to pull the tractor ahead gently while keeping the trailer brakes locked. This step is essential because it ensures that the connection between the kingpin and the fifth wheel is secure and correctly engaged. As you pull the tractor forward, you can observe if there is any movement in the trailer that might indicate improper connection. Ensuring that the connection is firm helps prevent potential accidents or disconnections when driving, as a secure link is necessary for safe operation.

Testing the connection in this manner allows for immediate feedback and lets the driver confirm that everything is adequately secured before embarking on the journey. All other options relate to aspects that might come after this confirmation or are checks that do not directly validate the connection's integrity.