Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Hi Tore

Yes, I believe this valve is complex without better photo

[tore]

Simon.
So far so good, usual high class standard. Looking forward to the rest.
Tore

[NZSnowman]

Hi Tore

Yes, I believe this valve is complex without better photo

[tore]

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

[tore]

Drainage/floodvalves.
Have read my ideas in retrospect I`m not 100% satisfied. I believe it is room for improvement. The only thing I`m sure of is, on the photos we see the top of the valvecage, the horizontal shaft and a fairly simple valvemechanism for the controlled checkvalve. No complicated gearwheels. So I`m open for alternatives we got to get Simons drawing correct..
Tore

[NZSnowman]

I think you right, I am sure the Germans keep this valve simple. We just need a few more good photo

[tore]

Yes Simon let`s have a few more photos !
Tore

[NZSnowman]

Tore, do you think the drainage pipe that runs between the aft trimming tank to the Control Room manifold and valve _h be the same diameter as the drainage pipe we been working on?

http://www.uboatarchive.net/U-570Plate6.htm

[NZSnowman]

Fig. 1. Drainage line (Brown-green-brown).

Tore, why you do you think the German, added a kink in the piping between the two frames?

[tore]

Simon.

Tore, do you think the drainage pipe that runs between the aft trimming tank to the Control Room manifold and valve _h be the same diameter as the drainage pipe we been working on?

http://www.uboatarchive.net/U-570Plate6.htm

Simon.
It migth be a bit smaller. The drain/flooding pipe should be able to handle large quantities of water, whereas the trimline usually handled moderate quantities. F.inst. when the order divingstations was given and the  crew moved to their station I remember 400 ltrs had to be pumped from aft trimtank to fwd. On a special occasion we flooded the diesel inlet shaft from the towercasing to the shut hullvalve in the engineroom, I guess it contained several tons of seawater which had to be drained into the engineroom bilge and pumped out via the drain/floodpipe in a hurry. It  should be possible to find the exact diameters though.
Tore
Tore

[NZSnowman]

Simon.

Tore, do you think the drainage pipe that runs between the aft trimming tank to the Control Room manifold and valve _h be the same diameter as the drainage pipe we been working on?

http://www.uboatarchive.net/U-570Plate6.htm

Simon.
It migth be a bit smaller. The drain/flooding pipe should be able to handle large quantities of water, whereas the trimline usually handled moderate quantities. F.inst. when the order divingstations was given and the  crew moved to their station I remember 400 ltrs had to be pumped from aft trimtank to fwd. On a special occasion we flooded the diesel inlet shaft from the towercasing to the shut hullvalve in the engineroom, I guess it contained several tons of seawater which had to be drained into the engineroom bilge and pumped out via the drain/floodpipe in a hurry. It  should be possible to find the exact diameters though.
Tore
Tore

Thanks Tore. I estimated the main drainage pipe to have a diameter of 120 mm, what do you think of about 80 mm for the other pipe?

[tore]

Simon
As a further guidance, the main drainpump (sentrifugal) had a capacity of 75 cub m/hour (impellors in paralell, low head) and 30 cub m/hour ( impellors in serial, high head) otherwise the capacity variation follows the normal sentrifugalvariation depending of the head. The trimpump (aux bilgepump, double piston) had a capacity of 18 cub/hour being a constant capacity as for pistonpumps. Thus the max. capacity of the main drainpump is about 4 times that of the trimpump.
Tore

[tore]

Fig. 1. Drainage line (Brown-green-brown).

Tore, why you do you think the German, added a kink in the piping between the two frames?

Simon.
I was not aware of this bend. My only idea is as follows: The diesel engineblock is casted in two parts joined by a flange right in this area. The steelstructure under the engine is pretty close to the to casted engine crankcase flange ( see picture below), may be they had to lead the pipe just around this flange. From an engineering point of view this is bad, almost unbelievable, but it is the only idea I have right now.
Tore

[tore]

Simon
I just had a look at your maindrain/flooding pipe drawing in the engine room. It seems that your pipe goes down and through the lubeoil storage tank. In general you would`t have a massive waterpipe in a vital lubeoiltank. If you are sure about that, my idea above is of cause not relevant.
Tore

[NZSnowman]

Simon
I just had a look at your maindrain/flooding pipe drawing in the engine room. It seems that your pipe goes down and through the lubeoil storage tank. In general you would`t have a massive waterpipe in a vital lubeoiltank. If you are sure about that, my idea above is of cause not relevant.
Tore

Hi Tore

I completely forgot about the lube oil storage tanks, but this pipe goes through the port tank. I will update my drawing tomorrow.