What component directly interacts with the locking bar to engage the locking system?

The cam is the component that directly interacts with the locking bar to engage the locking system. In intermodal dry cargo containers, when the door is closed, the cam rotates and pushes against the locking bar, securing the doors in place. This mechanism is crucial for ensuring that the container remains sealed during transport, protecting the cargo from external elements and potential tampering.

The other components play important roles in the operation or structure of the container but do not directly engage with the locking bar. For instance, the door panel serves as the main access to the container's interior, while the threshold plate provides a surface at the bottom of the door for sealing and structural support. The hinge assembly allows the doors to swing open and closed but does not have a direct engagement with the locking mechanism itself. Understanding this function of the cam is vital for effective inspection and certification of containers to ensure they meet safety and security standards.