Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Simon.
Engine clutches.
I just realized I forgot to put in my usual reservation: the above is my assumption . I migth add that the hydraulic air piston system is a bit uncertain.
Tore

[tore]

Simon
Pneumatic/hydraulic clutch system.
It might be I am mixing up with systems on other subs, but I base my assumption on that the pipes in and out of the operating cylinder are bigger than that of the airpipes to and from the operating handle. It looks as the pipes of the operating cylinder are going down whereas the air pipes are going up, a bit confusing .
The usual arrangement for this system has a floating corkplate as a barrier between the air and the oil ind the actuating cylinder. See sketch below.
Tore

[tore]

Simon.
Checking the u historia photo of the starboard clutch I believe I found one of the small air/ oil flasks for the actuating piston. Way under the propellorshaft you can see the top of the flask and the two pipes.
Tore

[tore]

Simon
The sketch showing the working of the pneumatic/hydraulic piston rod and the handoperated wormrod was not very clear as the  wormrod end was too short and the slot too long so here is a correction.
Tore

[TopherVIIC]

Simon and Tore -
I do not know if you have seen this wreck-dive video of U-251 at http://www.youtube.com/watch?v=Gw3EsX5bh4g
The dive footage shows extensive damage but there are sections where the divers are over the aft casement. Surprisingly, there is a lot of detail of the exhaust sections  between the casement and pressure hull, as well as air induction that you can pick out. B-)
Especially around 6:30+ 
Christopher

[tore]

Christopher
Fantastic .I`ll certainly scrutinise the details tommorrow. Thanks a lot.
Tore

[tore]

Exhaustpipe expansion.
I had another look at the divingvideo of U-251 provided by Christopher and located the exhaust pipes outside the pressurehull. What strikes me is the relatively complex arrangement of connections  between the group exhaust valve, 90 degrees bend, muffler and sparkarrestor, all connections have a short visible part of an uncooled smaller pipe entering the next component.
This is not without any reason. As I briefly mentioned before, free heat expansion has to be provided for and the connections have an  flange for a "stuffingbox" allowing the pipe to expand freely into the next component. This uncooled exhaustpipe stub has a small diameter (no coolingjacket) which makes it is easier to provide such an expansion stuffing box . I guess you find the same arrangement for the exhaustmanifold.
Tore

[tore]

Diving video U-251.
Having been a hobby moviemaker of diving videos I appreciate a good shot like the above movie. It is astonishing how some submarine wrecks  rest nicely at the seabottom.
We lost one of our U class submarines with all hands, just outside the Norwegian  coast in a German minefield February 1943. In 1985 the wreck was discovered and below is a photo of same resting almost like a display. The wreck is of course a wargrave, forbidden to be explored by divers.
Tore

[TopherVIIC]

Tore -
Do you know if there are surviving records of the operational/refit history of the KNM Kaura when she was with Norwegian Navy? Where might one go to request such things, and do you think that those with such records might be forthcoming to information requests?
What base did you operate primarily from? Would her Home Port possibly have records?

I, for one, would be willing to sift through such records if it could provide us with insights to her.
Christopher

[tore]

Christopher.
I don`t believe there are any such records available. I have German records of U 995 from the war time. Her Norwegian time as a "front" submarine was fairly short I guess  some 4-5 years, I was on board half the time. She had a retrofit every 3 years. For the last years she was acting like a school sub.
We operated out of the submarine base in Trondheim Norway as from just after the war. The Germans  build two large submarinepens in Trondheim of which we used one. In March 1954 we moved to the a temporary submarine base in Bergen using an ex. US workshop and depotship as quarter till a new main permanent submarinebase was built near Bergen and ready February 1960.  The old submarines like KNM Kaura  U 995  were scrapped in the beginning of 1960 as 15 new submarines were built and put into service as from early 1960 till 1967 of course these submarines are all scrapped as well and replaced by new ones. I believe some records could be found at the main submarine base Haakonsvern in Bergen otherwise  The Norwegian Naval Museum , Horten, Norway might have some records how willing they are to give away records I have no idea.
Tore

[TopherVIIC]

Thanks Tore -
I will see what, if anything, I can find out. Of course, since you and Simon have The engine room covered - I am focusing on the bow. The more I look, the more I see differences from other boats that would be interesting to track.
I know boats like that are a symphony of change - so we keep digging!
Have a good weekend!
Christopher

[tore]

Christopher.
You are right about there are differences between the boats even having the same buildingyears. When I got another boat, KNM Kya ex U 926 in 1954 I noticed quite a difference allthough the basic was of course the same. The boats were built at a different yards which apparently had different solution to many details. The most visible difference was probably U 926 had the new type of compasshousing whereas U 995 had the old streamlined. When you go into details as you and Simon, you are bound to find discrepancies between the boats. Below you are photos of KNM Kaura and KNM Kya showing the differences. In addition to the compass housing deviations they had 2 and 3 deck containers respectively and different schnorkel locking pin. For some reason the German fitted  Laboe U 995 with the new type of compasshousing.
Tore

[tore]

Simon
Pneumatic/ hydraulic clutch system.
When checking the u historia photo of the dirtyoil handpump on port aft engineroom bulkhead evidence is found that the airsupply to the clutch switching handle is coming from the top and the pipes out to the flasks are going down somewhere to the bilge thus the confusing photo from the starbord side is cleared up. I believe we can assume it is a pneumatic /hydraulic switching system with airpipes going down to the small flasks below the propeller shaft and oil supply/return  via sligthly larger pipes to the actuating cylinder.
Tore

[tore]

Simon.
Operating handle for clutches.
The operating handles for the clutches, painted red on U 995 are of the standard type sliding handle connected to a plug which fit into a slot locking the handle and cock in position. On the nameplate I have been able to decipher some of the text inboard reading EINR..... the rest is unclear to me, but I guess moving the handle inboard is clutching in.
Tore

[tore]

Simon.
Clutch handle.
Knowing your liking for details, I show you the locking of the clutchhandle as fitted on U 995. On the port engine the nameplate is gone and the handle is loose and placed upside down, by that displaying the plug which fit into the namedisc shown on starboard engine. The handle is springloaded and you raise the sliding handle by having your thumb on the protruding nob. Just a minor detail for your pleasure .
Tore