Simon.
Main exhaust system.
You are right there are not much pictures or drawings to find on the subject. The system consist of an inboard exhaustvalve in a watercooled housing going through the pressurehull. The valvedisc has a wormdrive connection for rotating the valvedisc ( grinding ) which is operated from the engineroom by hand, and a wheel for shutting the valve. You can find a picture on the U historia webside. On one side you see a square shaftend protruding out of the housing , that is the connection for handturning of the wormdrive. After the inboard valve the watercooled pipe makes a bend towards aft having a branch off pipe going forward to the ballast tank blowing panel in the controlroom and to the snortmast, I`m sure you know all about that, valves and pipejoining etc. There is an outer main exhaust valve pretty much the same as the inboard valve but the rotation ( grinding) of the valvedisc is done by pneumatic motor having the worm drive spindle through the pressure hull. The valve is shut by a handwheel in the engineroom up under the pressure hull. On the bad photo and drawing below I have tried to indicate the components. The outer exhaustvalve is used for adjusting the exhaust pressure in the ballast tank during exhaustblowing. After the outer valve the pipe turns into a silencer which from outside look like a watercooled barrel and the flanged to a smaller barrel which is a spark arrestor before going through the casing side.
Tore