Which component is primarily aimed at ensuring the safety of propane cylinders during transport?

The component that is primarily aimed at ensuring the safety of propane cylinders during transport is indeed the overfilling prevention device. This device is designed to prevent the cylinder from being filled beyond its safe capacity, which could lead to overpressure, leaks, or even explosions in the event of a temperature increase. By stopping the fill process when the cylinder reaches a certain level, the device plays a vital role in maintaining both safety and integrity during transport.

While safety inspection reports, labeling requirements, and maintenance schedules are also essential for ensuring the safety of propane cylinders, they do not directly prevent overfilling during the filling process. Safety inspection reports help in assessing the condition of cylinders before transport, labeling requirements provide important information about the hazards, and maintenance schedules ensure regular upkeep to maintain safety standards. However, none of these elements have the direct function of preventing overfilling, which is critical to safe cylinder transportation. Thus, the overfilling prevention device is key in mitigating risks associated with transporting propane cylinders.