Steam era boxcars used a number of door opening and closing mechanisms during the wood and steel construction period. The most common was made by Camel. There are a number of other mechanism such as the Union Duplex and Creco.
The picture shown above is the common Camel type. The railroad worker is in the process of attaching a seal the door hasp. The picture below is of the same application but from a different angle.
As a modeler we are fortunate to have these parts available from Chooch Enterprises.
You can find the Camel door opening and closing mechanism on the #215 sprue. You can purchased the parts via the Chooch website. They are only available direct from them.
The 1932 ARA boxcar shown above had a Union Duplex door and opening closing mechanism. This is a type that had not been produced commercially. I did a set of patterns for a Union mechanism for a 1932 boxcar kit that never made it to prime time. The Youngstown door has to be modified on the lower corners. Also a door lock and tracks were made for the door.
From time to time, I will touch upon other topics on freight car details. Proto48 is about the getting the details right.