Simon
Drainage/flooding valves.
I believe we have to look to the working of the system. The main drainage/flooding main pipe goes all the way from fwd. to aft, being able to bring the water in both direction. In those areas not centrally controlled you have branchoff pipes locally controlled, in some areas these branchoff pipes are fitted with controlled checkvalves shutting the branchoff to the mainpipe by a spring. The vital valves can be controlled from two positions, locally at the valve or via a shaft through a watertight or even pressuretight bulkhead adjacent to the valve.
I believe basically all the handcontrolled checkvalves are the same and the pictures of the checkvalves shows the top of the valves, the reason is that you clearly see a centrally placed watertight stuffingbox for the valvespindle, a lengthening rod would have a simple guidebush.
The support on the valvetop accommodating a horizontal shaft going through a bulkheadsealing to a handle in the adjacent compartment. On this shaft is fixed an excentric disc ( cam ) able to touch the top of the valvespindle. Locally at the valve is another handle different from the other as it contains a screwspindle ( see the square tap at the end) and at the other end a forked bush enclosing the horizontal shaft but not fixed to same.
Shutting and opening the valve is as follows:
1. Opening.Turning the shaft by a handle in the adjacent compartment cause the excentric disc ( cam) to force down the valvespindle, opening the valve against the springpressure. The screwhandle locally at the valve is not connected to the shaft and is not moving ( to avoid in case of emergency something should block the handle.) Shutting. Turning the shaft the other way and the spring is shutting the valve
2. The most common situation. In case of locally drainage (bilgepumping ).Opening. A wheel or handle is put on the square turning the spindle inwards thus locking the handle to the shaft. Turn the handle up against its stop (clearly visible) thereby moving the shaftcam about 90 degrees and opens the valve.
Shutting. Putting the screwhandle down to the other stop releasing the valvespindle and the spring shuts the valve. Unscrew the handle from the shaft.
The picture of the handle in the E-room looks indeed as connected to the checkvalve, it could be this is a handle on the shaft through the bulkhead for the same valve, because you cannot see any bulkhead bushing for the horizontal checkvalve-shaft. A reason could be that it had to be displaced and hence a crankconnection had to be made for the rotating camshaft for the checkvalve.
Well a long story about a relatively simple valve, but it`s the only idea I have for the moment.
Tore