Re: Firedoor on German locomotive

John,
You can see the Marcotti firedoor at work here:
https://youtu.be/S_fxpJMv3o8
Starting at about 4:25.
The door swings inward for a couple more reasons: IF a tube goes bust, it can't blow the door open. And if the engine is working realls hard yow won't have trouble opening the firedoor. It usually has three notches, one at just a gap open to let some air in, one at about 1/2 and one at fully open. In Germany (and most other european countrys) the engineer opens and closes the firedoor for the fireman.
To both sides of the actual door there are air channels to let air flow in, preventing the door fron clattering and helping with combustion. I have seen air cylinders mounted to them, like the ones on butterfly doors.
Yes, the round "thing" is the screw reverser, it makes adjustments real easy and precise. Mind you if you have to do switching with such a reverser!
Very best Regards,
Urias