Tores mailbox VIIC and VIIC/41 operation and technical details

[Don Prince]

Hello Mr. Tore and Maciek,


The hand-wheel for operating the stern buoyancy tank vent valve; it's position (between 6th and 7th frame) corresponds with the drawing:



http://www.uboatarchive.net/U-570/U-570DTPlate28.jpg


That means that the level near the Junkers exhaust valve (and interlocked with it) is not for operating the buoyancy tank vent valve, but for something else. Moreover, this lever (as well as exhaust valve) is located between 7th and 8th frame) and it does not match with the plate:


http://www.uboatarchive.net/U-570/U-570DTPlate28.jpg


So it has to be for something else. It is definitely interlocked with exhaust hull valve. I guess maybe it is some external flap of the exhaust duct?


1. The hardware in U-995 indicates the stern buoyancy tank hand-wheel still exists and is operational.
2. Linkage between the lever actuator and the stern buoyancy tank hand-wheel looks doubtful.
3. What is the lever actuator/interlock function?
4. The interlock lever drive shaft goes external to the pressure hull to control something?


Regards,
Don_

[Don Prince]

Hello Mr Tore,


I have taken what you previously provides and made some changes...



Drawing attached
 
1. 1st State - Junkers compressor not active - Exhaust flap valve shut and the grinding plate valve is shut (submerged)
2. 2nd State - transitional
3. 3rd State - Junkers compressor active - Exhaust flap valve open and the grinding plate valve is open and the diesel exhaust is directed to the external water cooled muffler

What do you think?


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


I have been working on the Junkers exhaust system and came up with what I believe may be the internal drive of the outer segment. This doesn't look to be a difficult gearing design since I had to work on NCR mechanical cash registers when I was 22 years old.


However, I have ran into a problem with the exhaust system.  It looks like the intermediate disk up near the upper pressure hull is out of time or sync...


I will attach a photo and the problem is marked.


Please advise...


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


I believe I know what happened to get the upper drive segment out of sync...  The hand-wheel provides a great mechanical advantage when applying force to its drive shaft. Then you can multiply that force times 10 with the final stage gear drive.


The final stage drive gear is taper pinned (heavy) to the drive shaft along with the lighter upper drive segment (smaller) taper pin. If for some reason the lever that locks the intermediate gear was not moved to the unlock position, and there was driving force applied to the hand-wheel, then you have a situation.  The force applied to turn the final stage gear, is applied to the segment meshed to the intermediate plate gear which can not be turner and will result in the small taper pin holding the segment to the drive shaft to shear.


Now, the relationship between the final stage drive gear and the upper drive segment no longer exists and there is no drive to the segment (it's broken)!!!


What do you think?


Regards,
Don__

[Don Prince]

Hello Mr. Tore and All,


If you zoom on my image, then it looks like the intermediate wheel is missing some teeth.  If someone has a better resolution image, then this can be confirmed...


Regards,
Don_

[Don Prince]

Hello Karel,


I will provide you with a link to Skizzenbuch once I get the junkers exhaust issue settled.  However, this version of Skizzenbuch will be in a PDF format and is not copy protected.  Therefore, on the condition that you will not distribute this version, then you are welcome to it.  Eventually I will get a program called "CopyProtect" which will allow the distribution of a PDF, but under the writers control (it encrypts the PDF and comes with an embedded viewer)...


The next time I post a new version of Skizzenbuch to my dropbox folder, then I will send you a link.  Please send me an email so that  I may use it to send you the link.


My email address is:


donprince5207@comcast.net


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


I have worked on an Junkers exhaust system based on the outer photos that are available...  Please advias as to your opinion which is highly valued.


Regards,
Don_

[karel]

Hello Don.This is wonderful news. I have sent you an email.


Thank you

[Don Prince]

I posted the latest version of Skizzenbuch 11 - 17 - M + I.pdf in the dropbox folder.


I expect there may be some changes after Mr. Tore and Maciek review the latest version.


Regards
Don_

[Don Prince]

Hello Mr. Tore,


The GW diesel engine had an RPM counter that looks to turn over at 1,000,000 rpm...  If the diesel engine was running at an average of 390 rpm, then it would take about 42 and 3/4 hours for the counter to turn over.  Was there some sort of a maintenance scheduled at a turn over? If not, then what is the purpose for this counter?


Regards,
Don_

[SnakeDoc]

Don,

to be strict, this is revolution counter, not RPM counter.
In my opinion, the turn-over value indicates that it was supposed to read off every 24 hour, and then the values were sum-up.
I cannot give you any schedule-periods, but engine revolutions as well as working ours were recorded in the KTB Maschine.
Some U-Boat KTBs had attaches: radio logs, maps, torpedo reports or engineering logs (KTB Maschine). In the engineering logs were recorded all information related with mechanical equipment of the U-Boat (among the others data related with diesel engines: fuel consumption, working time and so on). At the uboatarchive.net website are available some engineering logs.
For example:
http://www.uboatarchive.net/U-107/KTB107-6KTBMaschine.htm

	Port	Motor		Stb	Motor
	Days	Hours	Min	Days	Hours	Min
Total operating time since commissioning:	220	18	33	221	15	30
Total operating time during the last patrol:	37	7	37	37	22	15
Revolutions since commissioning:	83	148	596	84	922	374
Revolutions during the last patrol:	13	398	180	14	144	920

http://www.uboatarchive.net/U-518/KTB518-2KTBMaschine.htm
stb engine
operating time since commissioning: 2603 hours 4 min
operating time during last patrol: 943 hours 56 min
revolutions since commissioning: 33,349,060
revolutions during last patrol: 11,341,510

port engine
operating time since commissioning: 2598 hours 10 min
operating time during last patrol: 960 hours 28 min
revolutions since commissioning: 36,043,720
revolutions during last patrol: 11,412,440

--
Regards
Maciek

[SnakeDoc]

If you zoom on my image, then it looks like the intermediate wheel is missing some teeth.  If someone has a better resolution image, then this can be confirmed...

Maybe this photo is better.

--
Regards
Maciek

[SnakeDoc]

Hi Gentlemen,

while looking through the KTB Maschine, in this document I have found the following (the section regarding the issues with Junkers compressor):

After disassembly of the internal exhaust gas valve, it was found that the seat of the valve was burnt or ground out over half of its perimeter.  Repair was not possible by on board means.  The external valve is tight.

This fragment indicates that Junkers compressor exhaust hull valve consisted of internal and external part (what was not so obvious for me).
Maybe it looked as follows: in the early years of war, both valves were driven by two hand-wheels. This hand-wheels are visible at this photo taken on U 570:

Left hand-wheel drives the internal valve (water-cooled casing with thermalinsulation) while the right hand-wheel drives external valve (and that's why it does not have thermalinsulation, it is just a shaft going through the hull). Both valves are driven by hand-wheels and are fitted with valve state indicators. To close or open the valves, many turns are required, so one can recognize them as "slow-working" valves. That means that it took long time to open both valves fully, and before it was done, seawater breaks into the exhaust system.

When German recognized this problem, in the later U-Boats (like U 995) they interlocked the external and internal valves in such way that external flap could only be opened when internal valve was opened previously. In this design, hand-wheel driven, "slow-working" internal valve would be opened fully, and only then, external flap could be opened by "fast-working" lever (this lever could be rotated by ~330 deg, so it has lower radio-gear, requiring a greater force, and that's why long lever was provided). In the same time when the external flap was opened quickly, the Junkers compressor was started, and exhaust pressure did prevent water intrusion.

Generally, this idea is concurrent with Don's idea presented in his post.

--
Regards
Maciek

[tore]

Don and Maiek.
Regret I had to leave my mailbox for a while due to some family matters. I am just home for a few days before I leave up to my summerfarm for the year on late tuesday. My problem is then I am not sure when I get access to the internet, hopefully in a few days, may be wednesday/ thursday  April 26/27, sorry about this. I have briefly read the various proposals on the Junker and as I remember some of the " designs" I made on the exhaust system was, as I mentioned at the time, pure guesswork in lack of documentation. In the meantime Maciek has come up with an interesting image which together with Dons  sketches might give a better understandings on the matter. I shall look into this again, just a preliminary remark Don, the hull exhaustvalve normally shuts having the seapressure behind the valvedisc which means, I guess, the valvedisc on you sketch should be in the top chamber on you image.
Tore

[SnakeDoc]

Hi Tore,

it's great to hear from you again.

Gentlemen, if I recall correctly, some time ago we had discussed briefly (however I cannot find particular posts) about safety pins (or safety seals) securing the vent valves from being accidentally opened.

I have found few photos taken aboard of HMS Graph. They are showing the MBT 5 vent hand-wheel secured with locking pin, and MBT 3 port vent lever secured and unsecured.

--
Regards
Maciek