When positioning the converter dolly, when should you stop rolling it?

Answer: B — When the fifth wheel touches the trailer apron plate

Stopping when the fifth wheel touches the trailer apron plate is crucial for ensuring that the connection between the converter dolly and the rear trailer is accurate and secure. When the fifth wheel comes into contact with the apron plate, it signifies that the dolly is properly aligned and ready for the connection process. This step is essential because it sets the stage for the coupling mechanism to engage correctly. Maintaining this precise positioning helps to prevent misalignment issues that could lead to coupling failures, which can cause safety hazards during transport. Proper alignment ensures that the components will fit together as designed, facilitating a secure linkage that is vital for safe towing and stability on the road. Other aspects of positioning—like the alignment of the rear trailer or reaching designated marks—while relevant, do not address the direct mechanical connection that is critical for safe operation. Ensuring the fifth wheel makes proper contact focuses on the mechanical integrity of the connection, which is the most vital part of this procedure.