Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Very good Simon, it is quite a visible part of the engine so I guess it is nice to have it correct. I have not been able to establish the in and out pipeconnections on the knife filter. Some of them have connection in the bottom, others on the top. I would guess bottom towards the engine.
Tore

[NZSnowman]

Very good Simon, it is quite a visible part of the engine so I guess it is nice to have it correct. I have not been able to establish the in and out pipeconnections on the knife filter. Some of them have connection in the bottom, others on the top. I would guess bottom towards the engine.
Tore

I was just about to ask you this question and was writing it up but you must be faster than me I will feed them into the back of the filter.

I will post new drawings is a few day, as I am away tomorrow.

[NZSnowman]

Tore, here the fuel oil layer added, should keep you busy tomorrow

[NZSnowman]

Tore/or anyone, not sure if you know this, but the forum will resize my drawings to 800 px, if you left-hand click the drawings it will rescale the drawing to it original size.

[tore]

Very good Simon I`m off to bed now, may be you put the T handle on the filter by tommorrow morning.
Tore

[tore]

Simon.
You are right the fuel layer shall keep me busy today. I`ll start at the top. The tank you have drawn up under the pressurehull is the hearth or rather the stomach of the whole system. The tank is split in two halves along a mid shipline and function like a purifyer, clarifyer and a head/supplytank to the engines. It is fed by white pipeline  on the picture below from the fuel pressure watercompensated bunkertank system to the aft end of the headtank via cocks.
 During normal service you take fuel for both engines from one of the tanks, while the other is filled from the bunkertanks and then let the fuel settle so the water and impurities collects in the bottom of the tank, that takes a while but  it is ready for use when the other tank is nearly empty. Below is a drawing where I have tried to show the details of the supplysystem. Amongst the mess of arrows I have indicated a valve and line in yellow, leading fuel to the Junker compressor which we shouldn't`t forget this time. The system sketch is showing as usual the MAN system with fuel supplypump driven off from the camshaft aft end, as mentioned before remember on the GW it is driven from the crankshafts  forward end.
 With so many arrows  I think I better split this up and go into details of the supply system from the daytank in a separate post.
 A small detail to mention, the tank is fitted with 3 brackets on each side to the upper frames of the pressurehull, the aft fitting is  fixed by wire to welded on eyes to the plating as the tank end does not quite meet the aft frame. The light underneath the tank seems to be on the small side , the diameter is about a 5th or 6th of the length of the tank.
Tore

[tore]

Simon
The fuelsupply system from the daytank.
The fuel from the overhead daytank goes from the selected tank via a cock which, when open for delivery (red) allows the other tank to open for supply (green). The red supply lines to both engines goes along the engines  as a black pipe ( it was never black in my time) to the selection cock on the forward engine side, the system from here has been explained previously. On the forward side of the daytank are sight glasses for each tank as well as drainpipes with cocks and ventpipes all ending up in a collecting tank. These pipes are all fitted on the port engine.

[SnakeDoc]

Hi Simon

On Plate 10:  Fuel oil compensating system (circulating water under pressure), the handle for valve 'B' are located within the engine room?

In my opinion, there was no need to make this valves operational from inside of the pressure hull.
Moreover, in the section Openings in the pressure hull of http://uboatarchive.net/Manual.htm, there
is no mention about shafts for these valves (either in diesel engine room as well as in Control room).


--
Regards
Maciek

[tore]

Hi Simon

On Plate 10:  Fuel oil compensating system (circulating water under pressure), the handle for valve 'B' are located within the engine room?

In my opinion, there was no need to make this valves operational from inside of the pressure hull.
Moreover, in the section Openings in the pressure hull of http://uboatarchive.net/Manual.htm, there
is no mention about shafts for these valves (either in diesel engine room as well as in Control room).


--
Regards
Maciek

Yes I agree Maciek, see my answer nov. 23rd.
Tore

[tore]

Simon
Fuel supply system from day tank.
Checking my post earlier today on this subject I realize the relevant picture was not posted, I guess it is becoming too many pictures. Anyhow below is the picture which I hope gives a better understanding of the text.
Tore

[tore]

Simon.
Fuel drain.
The main fuel drain on the engine goes along the engine just about where the cylindercovers meets the cylinder block, it collect the spill from each cylindercover via funnels and leads to the forward of the engines joins the drain (yellow) from the knifefilter before it drain into the fuel draintank. It is no T piece where the fuel filter enters the maindrain, just a welded branch with threads for the connection.
Tore

[tore]

Simon.
Crankcase doors.
Now we are really going into details, but I happened to notice some small discrepancies on your bedplate/ crankcasedoors. As you see on the picture below, the stiffening knees between the crankcasedoors are ending a bit higher up between the doors and the narrow end cover up forward is protruding further down than the ordinary crankcase doors. The narrow frontcover is just a plate. Crayzy details hardly noticed by anybody but mee. 
Tore

[tore]

Simon .
Drain box.
Realizing your latest drawing  may not yet be completed I shall nevertheless mention this small detail.   The drainbox up forward I believe it is a bit larger almost the full height of the camshaftcover, see picture below.You said it before, you love details.  
Tore 

[tore]

Simon.
Crankcase doors and floorplating.
You have probably not yet fitted the floorplating in the engine room, prior to that, be aware of a detail. It is a fairly big step down to the floorplating between the engines, the reason for that is you want to have access to the crankcase through the crankcasedoors without having to dismantle the floor. By lowering the floorplates you are making it difficult to have access to the engine top which require frequent inspections and maintenance. A stepplate is hinged all along the engine  right below the camshaft covers. On the U 995 it is folded down, howewer when needed you fold it up and behind the plates are folded in brackets which you fold out to get support for the plates. See picture below. You can get further detail on the U historia.
Tore

[NZSnowman]

Hi Tore

Just letting you know that were will be no new drawings for the next few days. I am taking a break from drawing and catch-up on some other work.

Simon.
Fueloil compensating valves fuel oil saddle tanks.
The upper drawing you are showing is the system outside the pressurehull and I don`t believe the valves are operated from inside the pressurehull. The fuel/ballast saddletank 2 and 4 starboard and port are just made of light steel sheets and do not withstand any large pressure. They are equipped both as full fueloil bunkertanks and  full ballast tanks with all the connections required. The encircled valves have two positions either in direct connection with the head/buffertank in the tower or in contact with the sea via a small compensatingbox in the bottom of the tank. As fueltank the first position shall be used to ensure the compensating head is allways positive but not exceeding the differential pressure (the hight difference between the headtank in the tower and the fueltank). Eg. irrelevant of the ambient pressure regardless the diving depth. 
Tore

Tore, that dimension do you think this pipe would be? I was thinking about 75 mm.