Can someone tell me the real reason for the hole in the ends of some covered hoppers?

I am starting to kit-bash Tichy flats into early circus loading tofc. Most pictures of models have a brake wheel sticking up about 4 feet in the way of the truck driving across the ramps. I am having a hard time finding pictures of a converted flat or box car that had the brake wheel relocated somewhere. Also on some newer  89 foot cars there is a post on the side,near one end, that has the chain connected to it but no wheel. Is that some sort of lever that actuates the parking brake linkage?

Can anyone suggest a can motor a little smaller than the old Pittman motors?

My target is a drop-in replacement for most brass steam locomotives. I will create a bracket to mimic the Pittman mount point, a 4-40 x 3/16 screw

The width is the most critical dimension to fit in most brass steam locos.

Overall dimensions less than or equal to

I got a request from my son wanting information about Prussian/German trains in 1860 to talk about them in his European history class at college/university.

I have not done any research yet myself, but I was thinking that instead of just googling I would ask here for recommended resource, hoping someone who has researched the subject could point me to a good link or two to read.

Thanks in advance,