Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

The flexibility of the various system. As I have mentioned before the systems have been designed for many alternative solutions left to the engineroom crew skills, experiences, and creativity to utilize. One important feature is the aux. luboilpump function as a fueltransfer pump. Being able to bunker fuel from any sources might be vital. This is a detailed description of one solution of many.


Bunkering fuel utilizing the aux. lubeoil pump.
One of the aux. lubeoil pumpoperations is pumping fuel from a source not capable of of supplying fuel with sufficient pressure. Referring to the plate 9 below it goes as follows:
 In the casing is a hoseconnection leading to a fueloil pipe which enters the pressurehull via a hullvalve (a). The pipe, marked dotted green, enters a nut and bolt filter and continues to a suction inlet in a valvechest underneath the writing plate on the forward portside engineroom bulkhead.
In the event of bunkering fuel from a source not capable of supplying fuel against the head of the watercompensated fueltanks the aux. luboil/fuel pump suction is connected  to the suction connection b2. on the valvechest and the pump discharge the fuel into the chest pressurechamber via valve b1. By opening valve valve c in the chest the fuel continues to a filter before a fuel meter. Then the pipe return to the valvchest via cock e and leave the chest by opening valve b6. then via  a bypassfilter before entering a selector cock e1 which makes it possible to select port , starboard or both daygravety tanks which then can be topped up. From the selected gravety tank the fuel passes a fuel meter, a branch off to the Junker compressor to a 3 way cock in a crossover pipe to the suction of the engineattached fuel supply pumps port and starboard. In spite of the plate 9  the GW engines these pumps are driven from the crankshaft up front of the engines. From the supplypump the fuelpump deliverypipes goes to a finefilter on the top of the camshaftcasing the filter is not shown on the plate 9.
By using the same methode you are able to bunker any internal fuel tanks as can be seen on the plate 9.


Tore

[Don Prince]

Hello Mr. Tore,

I believe valve (k) is an overpressure device to limit the fuel oil pressure to the injectors. If one of the diesel engine's fuel oil pumps failed, then you could use compensation water pressure from any external tanks, or the Auxiliary Fuel Oil Pump to provide fuel oil to the injectors by bypassing the failed pump using the internal fuel oil tanks. Also, while using the compensation water pressure or the Auxiliary Fuel Oil Pump with a failed fuel pump the day tank is bypassed...

My question is: When you bypass the failed fuel pump and provide fuel oil pressure to the injectors on that diesel engine. However, the engine with the functional fuel pump will see the increased fuel oil pressure at the pump's head. Does valve (k) just feed back any excessive pressure to the pump head, or do you have to bypass both fuel oil pumps to avoid an overpressure situation on the functional fuel oil pump?

Regards,
Don_

[tore]

Don.
As the fuel centrifuge was discarded, great care is taken to prevent accidental mixing of fuel and water, hence the double daytank has two purposes 1. Being a buffer placed as high as possible in the engine room to provide suctionhead to the engineattached fuel supply pumps, which are positive displacment pumps.  2.  acting like a settlingtank by being a double tank able to settle and drain the impurities in the tank not in use.
Generally all positive displacementpumps have, contrarly to sentrifugalpumps, a reliefvalve intergrated returning the liquid from the discharge to the suction side to prevent dammage in case accidental shutting the discharge.
The HP fuelplunger pump for each cylinder is a positive adjustable displacement pump having supply from the engine attached supply pump, but  would be able have positive fuelsuctionhead by the highly placed fueldaytank in case of failure of the engine attached fuelsupply pump. The daytank capacity of 700 litres would be able to serve both engines in the highly unlikely event of both fuepsupplyumps would fail.
Tore

[Don Prince]

Hello Mr. Tore,

Are you telling me that all of these scenarios will work?

1. Both fuel oil supply pumps failed and fuel oil will be supplied by one side of the day tank and because of the height of the tank (head pressure) above the bypassed fuel oil supply pump and on to the injectors. I thought there was a problem with the low head pressure from the day tank (i.e., The main reason for the fuel oil supply pump)?

2. Both fuel oil supply pumps failed and fuel oil could be supplied from any external fuel oil tank. The pressure head would be fairly high. The fuel will bypass the day tank because the valve is set in the pass-through position, thus providing adequate fuel pressure bypassing the failed pumps and on to the infectors. 

3. Both fuel oil supply pumps failed and fuel oil will be supplied from an internal fuel oil bunker via the Auxiliary Lube Oil Pump going through the day tank selection valve set in the pass-through position and bypassing the failed fuel oil pumps and on to the injectors...

Regards,
Don_

FYI - From Skizzenbuch page 73 - "If the attached fuel oil gear pump failed and must be by-passed; the pressure head from the gravity tanks height above the diesel engine (image below and less than 2 m WC) is probably not sufficient to force fuel through the filter and supply pipe to the high-pressure fuel injection pumps. Hence, you use the full compensating water pressure from the header tank (some 5 m WC) to provide the needed pressure. The compensating water pressure head goes directly to the fuel injectors supply pipe and by-passes the gravity tank."

[tore]

Don.
The fuelsupply pump can be bypassed by the cock e but have a  knifefilter between the suplypump and the HP pumps which would cause  some resistance which might require a larger head than obtained by the daytank. I have not tested this unlikely event, but would in case of emergency have tried to connect the other engines supplypump before using the compensating water pressure to the daytank.
I am not sure I understand your next question. In case both engineattached fuelsupplypumps fails you would be able to use the separately driven fueltransferpump via the day tank.
Tore

[Don Prince]

Hello Mr. Tore,


While we are still looking for the fuel oil valve chest under the floor plates, Patrick in Germany came across the brackets outlined in the attached photo. Do you remember what was attached?


Regards,
Don_

[tore]

Don. I cannot remember in spite of pondering for a couple of days.
Tore

[Raymic1]

Don
Just wondering. Are you working with Paul- Patrick Schroder or a different Patrick at U995?

[Don Prince]

Patrick Salmen who has a great collection of digital copies of original U-Boat manuals and documentation. He seems to get good access to U-995 and does some volunteer work.


Regards,
Don

[Raymic1]

Patrick Salmen who has a great collection of digital copies of original U-Boat manuals and documentation. He seems to get good access to U-995 and does some volunteer work.


Regards,
Don

Ah OK. I thought it might be Patrick Bateman The Engineer Guy, he also has a lot of original U-boat docs that haven't been published yet.

[Don Prince]

Hello Mr. Tore,

Since 2018 when I released Skizzenbuch, there were 3 websites that I authorized the book's distribution: AMP, The Subcommittee, and Wehrmacht Awards. The latter 2 were able to provide me with a download count, and there was a total of well over 13,000 downloads of Skizzenbuch. In addition, there were about a half dozen pirated sites in Europe and Asia that charged for a high speed download option which was a rip-off! Their initial slowed download speed was taking well over 5 hours, and the high speed download was about 3 minutes (which was about the normal speed from my Dropbox account).

About 6 weeks ago, I decided to look into doing an Amazon.com Kindle publication of Skizzenbuck in a Print Replica format; basically its like a pdf and Skizzenbuch was published on December 6th... I set the price at the minimum charge of $2.99 on the Amazon Website/Kindle Store. I doubt if the royalties will ever cover the yearly cost to maintain the Kristallklar Publishing, LLC, Corporate status in the state of Georgia, the Registered Agent fees, and the initial US Copyright cost. Here is what the Skizzenbuch eBook cover looks like (see the attachment)...

Mark Hessburg was the first person to purchase Skizzenbuch from Amazon's Kindle Store and write a review; now that's a good personal friend...

Regards,
Don_

FYI... I pulled the plug on the free Skizzenbuch download from my Dropbox account.

[Don Prince]

Hello Mr. Tore and All,


Merry Christmas and Happy New Year to All - May we all enjoy Christmas with our families and have a happy and healthy new year...


Kind regards,
Don_

[tore]

Don.
Returning the whishes
Tore

[VIC20]

Merry Christmas.


U 995 Christmas snow mod:

[SG]

Merry Christmas!