Tores mailbox VIIC and VIIC/41 operation and technical details

[Don Prince]

How about this....  Don_

[tore]

Don.
The image correction 4 you are referring to is erroneously marked external exhaustflapvalve by me and is the internal main (Group) exhaustvalve operated by the red handwheel. The handwheel turns a spindle with wormgear engaging a gearsegment attached to a hollow fulcrumshaft  , (yellow on my sketch) connected to the rotation center point of the the flapvalve disc having a geared rim. The shaft ends in a valveindicator (pointer) forward outside the gearsegment casing, showing the position of the valvedisc. Inside the fulcrum shaft is a (black) shaft with wormgear engaging the valvedisc gear rim  for turning (grinding) the valvedisc against its seating. The shaft is protruding outside on the aft of the valvecasing and ends in a square for a ratchet bar for moving (grinding) the valve disc. So the inner main exhaustvalve is ground by hand. The outer main exhaustvalve (before the silencer) has a similar arrangement but the shutting and opening of the valve is done by the wheels forward of the inner mainvalve handwheels. The operation transmission to these valves are done by bevelgears and rods outside the pressurehull and the grinding is done by the pneumatic motors driving rods and bevelgears turning the valvedisc in the valvecasing outside the pressurehull. Basically the same way as the inner valves but pneumatically driven instead of the hand ratchet rod. Thus the aft handwheels are for the inner valves, the forward handwheels are for the outer.
Tore

[Don Prince]

Hello Mr. Tore,


Does this drawing look OK?


Don_

[tore]

Don.
This looks excellent except the arrow to what you call internal flapvalve gear segment point to the pneumatic motor for the drive of the grinding rods for the main outer exhaustvalve disc.  As the combination of  shutting and grinding of the valve makes it difficult to understand I made a sketch below showing the working principle of the mechanism for the inner valve.
Tore

[Don Prince]

Hello Mr. Tore,


I made the arrow longer so it is touching the segment casing...  Uploaded corrections to dropbox...  The location of the flap valves internal and external is a bit confusion because the external exhaust flap valve casing is outside the pressure hull and farther back. However, it's the drive shafts that place the controls farther forward ahead of the internal exhaust flap valve controls in the diesel room ceiling.


I liked the last diagram you posted showing the internal exhaust flap valve drive segment...


Regards,
Don_

[tore]

Don.
I just checked you to days corrected edition of the Skizzenbuch in the dropbox. I still think you should lengthen the arrow for the gearsegment of the inner main exhaust valve pointing at the pneumatic motor for grinding outer main exhaustvalve.
Tore

[Don Prince]

Hello Mr. Tore,


I did take your suggestion and lengthened the arrow  However, I posted the old photo back into Skizzenbuch.  I posted the correct photo and updated Skizzenbuch in dropbox.  below is the photo that is now in Skizzenbuch... 


Regards,
Don_

[tore]

Don.
That`s it
Tore

[tore]

May be we get a bit serious in the play of VIIC details. The other day I was looking into a cross section of MBT 3, suddenly this picture turn up in my head. Might be a new avatar?
Tore

[SnakeDoc]

May be we get a bit serious in the play of VIIC details. The other day I was looking into a cross section of MBT 3, suddenly this picture turn up in my head. Might be a new avatar?

Haha, Tore, great picture

--
Regards
Maciek

[tore]

Don.
All of a sudden I remember a manometer for the exhaustgaspressure in the exhaustgasmanifolds which could be used for adjusting the exhaustgas blowing pressure as well. It is placed on the forward stb. side of the housing for the Roots blower. The manometer shows the pressure in ATU (overpressure) and thus have scale from 0 to 1. I am not sure but may be it was installed in relation to the schnorchel installation. In addition, the engine exhaustmanifolds have a reliefvalve up front of the manifold. Particulary during schnorcheling these valves could lift, letting in an unpleasant dark exhaust into the engine room.
Tore

[tore]

Don.
Having looked through your Skizzenbuch I wonder why you have not included a main item as the schnorchel system. Introduced in August 1943 as a counter act to the allies air superiority it was an important conversion for the German uboats in 1944-1945. As we have discussed before you can`t include everything, but I guess this is an important detail of the submarine WW2 warfare which is worth while to include.
Tore

[Don Prince]

Hello Mr. Tore,


I am still working on the schnorchel addition and will update Skizzenbuck in a few days...


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


Perhaps you can help me with this diagram...


1.  The hydraulic pressure oil cylinder has 150 and the greek letter theta?  What does that theta mean?
2,  How do they know the schnorchel mast is fully up or down?  Would that cause an increased pressure reading on the manometers so they know the mast is fully up down?
3.  Does the throttle switch control valve determine the direction of the piston drive? Mast Raise is high pressure oil and mast Lower is hydraulic oil back to the source inside the pressure hull.
4.  I believe things are reversed when lowering the mast.  Is that true?
5  Any other comments about the diagram?


Regards,
Don_

[tore]

Don.
1. This is the international letter for diameter in this case 150 mm.
2. It is an indicator up forw. port side in the control room see picture below.
3. Yes it is a handoperated switch connecting the "raise" side of the piston to the hydraulic pressure system and the "lower" side to the hydralic oilreturn see picture below.
4. Yes
5. The sketch is not showing the handle for lowering/ raising the mast, see my picture.

Tore