Rheinmetall fuze wiring diagram

[Bellifortis]

Does anyone of you know, what meaning the small letters : (a, b, c, d, e,f,....and especially bsp and bz ) mean ? You find diagrams like that in many published books, even recent ones, but never any legend explaining these small letters. All I'm shure of is, that b = electric ground/earth. SX 5 and SX6 are electric igniters of different sensitivity. Mostly the points marked with these letters are the soldering connections of the wiring, but not always.
Awaiting your valued input, I remain with kind regards,
Bellifortis.

 

[John D. Bartleson Jr.]

Sir
The letters in your diagram may just be a legend key and explained in the text with the drawing. Notice that the letter "b" always denotes a ground in the circuit.
Regardcs,
John

 

[Snufkin]

Single letters and strings of letters on schematics are purely for convenience to define operating voltages, and referred to elsewhere in the documentation. So instead of, for example, referring to "the voltage at the junction of resistor R1 and capacitor C3", it is simply V(h). More interesting signals or voltages, other than power supply or DC biasing, might have letters like DEM, PLL, ADC1 etc, etc.

Might z of bz refer to znden for igniting? That voltage is directly on a bridgewire.



Edit: slow typing - concur with John, a legend explained elsewhere in the document.

 

[Bellifortis]

Hi guys,
the legends to those letters is what I'm exactly asking for. These diagrams have been copied 100000nds of times all over the world in the last 70 years, but nowhere, not even in the original fuzehandbook documentation have I found an explanation. Snufkin, your thoughts are pointing in the right direction. "bz" may mean that this is the fuse legwire connection to ground (-), like an electricity flow diagramm explanation. The fuze designer Rhlemann had a traditional german electrical engineers education and knew nothing about fuzes when he started work at Rheinmetall in 1926. At the time much importance was placed on traditional engineering drafting skills at Rheinmetall. I assume that this type of lettering comes from traditional electrical engineering and is not peciular to fuzes. Nowadays with CAD design those traditional skills are not used any more. I have no engineering and electronics background, but somebody here should be able to read the diagram. Without understanding what the small letters mean, one is not able to understand fully the working of the fuze. I assume its a timefuze, because of the tube, but do not understand the design differences between it and the El.AZ (9). This fuze design never made it apparently, as I have never heard of an actual El.AZ 32. As I said before, nowhere in this documentation (its a copy for the patent department of the company) and nowhere in the thousands of pages of fuze documentation I have ever seen, is the legend written out, so I assume that this is basic electrical engineering drafting that everybody understood at the time because it was generally used. I don't know if this was peciular in Germany at the time, but would expect that in other countries electrical engineers used the same or similar diagram drafting skills and methods. I'm still hoping for an better explanation.
Regards,
Bellifortis.

 

[Bellifortis]

Hi Snufkin,
thank you for your answer that put me on the right track. It's a shame for all the german speakers, including quite a few professionals and also including me, that an english speaker should come up with the right lingual connection. "bz" is the ground wiring connection with one legwire of the fuse and most probably "bsp" is the wiring connecton of the reservoir condenser with ground. When I thought about your answer, while watching TV last night, I came up with this logical lingual connection. "sp" stands for the german word "Speicher" (reservoir). The other letters I presume are just the soldering and sometimes twisted wire connection points in the wiring. A small hint like yours can be a great help in advancing ones understanding. Thanks again Snufkin.
Regards,
Bellifortis.

 

[Snufkin]

Hi Bellifortis,

I was scratching my head over what bsp might be, and your suggestion of reservoir is very plausible. C(a-bsp) is the main charge storage for firing the bridgewire, whereas I'm fairly sure C(c-bz) is just a decoupling capacitor to prevent premature ignition by a current surge on switch on. There are symbols on this schematic which I don't recognize: the components between nodes g and h, and between nodes c and Sx5, and also component R 19 - this looks like a (2-terminal) valve component which is even before my time. Do you know what they are? Do you see them on the schematics for other fuzes?

All the letters (a....z) are just node identifiers, while mestelle is obviously a test point at node f.

Do you have the schematics for other fuzes?


Tom.

 

[Bellifortis]

Hi Tom,
these are the normal trembler impact switches, as found in most Rheinmetall fuzes. The "Rhre 19" is a tube, like in the (9) electric time fuze, that becomes conducting at a certain voltage equilibrium. I do not have the electrical values of these old differently numbered tubes. The 1. US VT-fuze was based on I think 4 tubes, with up to 4 connections. These diagrams you find in the original Air Force fuze handbook (L.Dv. 152, Teil 1, 2, 3, 4, 5 and Anlage 1 and 2,6 , 7 up till 31) These should be available at your archive. Some parts like for the (17) are available online (thanks to another BOCN member). I myself am looking for copies of this Luftwaffen Dienstvorschrift 152. These diagrams have been copied in many, many postwar books and training manuals for EOD all over the world.
I'm not an electrical engineer. But with all the values known in the diagram you can calculate the workings. Mr. Rhlemann wrote a very nice complete overview on the technology of " The electric Projectile Fuze" in 1947 for the French government, which took him 3 months to write and for which he recieved a fee of 3000,-DM, just a few days after the DM was introduced. There are quite a few pages just with the electrical formula to calculate a Fuze. I have no electronics background, so this is above my knowledge.
I have the diagrams for most fuzes somewhere in my library, so if you would like anyone special, I can make a copy. There is a nice book written by Peter Voss (retired head of EOD in Hamburg) "Deutsche Bombenznder im 2.Weltkrieg", which he sells for 49,-Euros. There are many diagrams in this.
Regards,
Bellifortis

 

[Bellifortis]

Hi tom,
here now is a detailed foto of the trembler and contact ring parts you did not recognise in the diagram. They were not produced at Rheinmetall, but bought from another manufacturer and only assembled at the Smmerda or Breslau fuze factories.

 

[millsbomber]

May Be a old wiring route might help,,,,, Dave

 

[Bellifortis]

Hi Dave,
thank you for showing these nice old displays. I downloaded the other ones you showed before.(Thank you). These are so individual, I have never seen anything like it and all with original components. Do you have any information on the artisan who made them ? Nothing I have ever seen compares to these so simple but clear made displays.
Regards,
Bellifortis

 

[millsbomber]

Well i brought them from a collector of SS uniforms just outside Antwerp, he had some very good contacts and a super collection, alas im no longer in contact with him, it was said that a British officer from the Royal engineers followed the advance of the Allies and stopped in Belgium to help with the clear up, he made these for the Belgium EOD from recovered examples, he must have started his service early on as there were some early eod tools like Crabtree dischargers and BD sugar tins and lots of SOE items that must have been handed in after the war, all the boards need repairs but now and again i find a rotten fuse and strip it back for parts,,,,,, Dave

 

[Snufkin]

May Be a old wiring route might help,,,,, Dave

View attachment 73558

Dave, thanks for showing that display. A very interesting item. However, maybe that one has suffered misplacement of parts and wires over the years as it does not actually reflect the circuit diagram (attached).

For those electronically minded, spot the differences...



Tom.

 

[Snufkin]

Hi Tom,
these are the normal trembler impact switches, as found in most Rheinmetall fuzes. The "Rhre 19" is a tube, like in the (9) electric time fuze, that becomes conducting at a certain voltage equilibrium...
Regards,
Bellifortis

Hi Bellifortis, thanks for explaining about the tumblers and the glow tube. The original diagram is a curious hybrid of electronic schematic and mechanical engineering drawing, which kind of threw me. Once the electronic symbols for the mechanical and pyrotechnic switches are substituted, the operation of the circuit becomes clear. The glow tube is basically a high voltage switch that permits firing of the main ignition pellet SX6. The igniters C25 and SX5 allow simultaneous switching in and out of grounds to the main igniter circuit, and it is this overly complex arming mechanism that probably stopped the El.Z.(32) from entering service.

Thank you for the book references for fuze information, but thanks to another BOCN member I now have the information I need to understand the operation of all the fuzes. Thank you also for your first post in this thread - I've never had any interest in German ECR fuzes before now, but on inspection they are quite simple devices. Simple but deadly.



Tom.

 

[Bellifortis]

Hi Tom,
I had lost interest in these fuzes more than a decade ago. It was a picture of the El.AZ m.B. here, which I did not know existed before, that got me hooked and started on an odyssee of research that is still continuing.
Regards,
Bellifortis.

 

[Bellifortis]

Hi Bellifortis, thanks for explaining about the tumblers and the glow tube. The original diagram is a curious hybrid of electronic schematic and mechanical engineering drawing, which kind of threw me. Once the electronic symbols for the mechanical and pyrotechnic switches are substituted, the operation of the circuit becomes clear. The glow tube is basically a high voltage switch that permits firing of the main ignition pellet SX6. The igniters C25 and SX5 allow simultaneous switching in and out of grounds to the main igniter circuit, and it is this overly complex arming mechanism that probably stopped the El.Z.(32) from entering service.

Thank you for the book references for fuze information, but thanks to another BOCN member I now have the information I need to understand the operation of all the fuzes. Thank you also for your first post in this thread - I've never had any interest in German ECR fuzes before now, but on inspection they are quite simple devices. Simple but deadly.



Tom.

Hi Tom,
if you understand the circuit, please explain it to me noneducated electrically. As I read it : The plunger is shown in the nondepressed position. The charging plug-on will depress the plunger and on release of the bomb electricity will flow from one terminal of the batterrie through the plunger - the upper springcontact-via "a"-through "bsp" charging this storage condenser-to the knoblike device touching that small cylinder (I don't know what this is)-to ground "b" back to the other terminal of the batterie. At the same time the 0,1 microfarad condenser on the upper right is charged and through the vibration of the releasing bomb the tumbler-switch "h" will close the circuit and fire "C25" instantly. This I suppose will close the switch below "C25", so this is just an arming delay for the tube circuit "R19". This will be out of circuit upon release and only after gets ground connection via "f". The big 1,4 microfarad condenser charges the 0,05 microfarad one that fires "SX5" on closure of the vibration switch (sudden deceleration) after an arming delay. "bsp" will also charge via "a" across the resistance through point "d" the 0,4 microfarad condenser that is also connected through "bz" to the igniter "SX5". So this igniter has 2 firing circuits closed by the same vibratory switch. Because of the different sizes of these firing condensers I expect different arming times for these 2 circuits. The 0,2 microfard condenser is also charged from "bsp" through 2 resistances and as soon as this has reached the firing voltage of the tube "R19" this will become conducting and fire "SX6". This would be a pure timefuze function. Am I right so far ? What do you think was the intention of the designer for this design ?
Regards,
Bellifortis.

 

[Snufkin]

Hi Bellifortis,

Sorry for the delay, Ive only just found your last post and question. As you say, the fuze is a pure time fuze.

I understand most vibration switches required an acceleration of around 50G to make a contact. Assuming the two vibration switches in this El. Z. (32) are these type, then I doubt that they would operate on release of the bomb. They are designed purely to operate when the bomb impacts.

Also if the ground connection at f is to be made immediately on bomb release, then it would make more sense to connect f to bz.

Operation.

With the plunger depressed (bomb in bomb bay):

C(g-b) is charged
C(a-bsp) is charged
The spring clip connection to ground (below the Sx5) allows reservoir C(a-bsp) to charge.
There are no ground connections to C(c-bz), C(d-bz) and C(e-f), so these capacitors do not charge.

Plunger released (bomb released):

Ground connection bz is made so C(c-bz) and C(d-bz) charge from the reservoir C(a-bsp) during the travel of the bomb.

Bomb impacts:

Switch(g-h) operates and C25 fires to complete the ground to the main igniter circuit (glow tube, Sx6, etc).
Switch(c-Sx5) operates and C(c-bz) fires Sx5, removing the ground spring clip connection and thereby removing the ground connection to C(a-bsp).

C(e-f) is charged from C(d-bz) via resistor R(d-e). When the voltage on C(e-f) equals the striking voltage of the glow tube, the main igniter Sx6 fires and the bomb explodes.

Without knowing the resistor values it is not possible to say what the timing values are for this fuze. Given the ratio of C(d-bz) to C(e-f) as exactly 2:1, and that the primary reservoir C(a-bsp) is not used to charge C(e-f) directly (it is actually removed from the circuit and C(d-bz) charges C(e-f) ), then the delay is short, perhaps 0.1-10s, and programmable, proportional to the initial voltage applied from the aircraft. This might suggest the fuze was designed for an armour or bunker piercing bomb, using an accurate electrical variable time delay instead of a pyrotechnic delay pellet.



Tom.

 

[Bellifortis]

Hallo Tom,
I just read your post. With "pure time fuze" function, I just meant the seperate circuit with the glow tube. This is combined with a PD circuit (the trembler switches) in this fuze, so you might have an electrical double action fuze. I thought, that the upper right trembler switched circuit with C25 (this is no igniter designation, I suppose a pyrotechnic switch, but have no proof) is used as an arming delay, to give the bomb some clearance away from the plane before current can pass to/through (dangerous current surge ?) the glow tube. For digesting your answer fully I have to sit down with it and think a little. I'll get back to this some time later.
Wishing you a Merry Christmas, I remain with kind regards,
Bellifortis.

 

[Bellifortis]

Hi Tom,
I still did not find the time to think over your reply, but I discovered something else, reading. The designation C/25 was used for bridgewire primers in 15 and 20mm cartridges for synchronized Mauser aircraft MG's. Why such a primer would be used in this application, there is nobody left alive to ask. The Rheinmetall Breslau factory was the main manufacturer of electric primers, besides the el.fuzes.
Regards,
Bellifortis.

 

[Bellifortis]

Hi Bellifortis,

Sorry for the delay, Ive only just found your last post and question. As you say, the fuze is a pure time fuze.

I understand most vibration switches required an acceleration of around 50G to make a contact. Assuming the two vibration switches in this El. Z. (32) are these type, then I doubt that they would operate on release of the bomb. They are designed purely to operate when the bomb impacts.

Also if the ground connection at f is to be made immediately on bomb release, then it would make more sense to connect f to bz.

Operation.

With the plunger depressed (bomb in bomb bay):

C(g-b) is charged
C(a-bsp) is charged
The spring clip connection to ground (below the Sx5) allows reservoir C(a-bsp) to charge.
There are no ground connections to C(c-bz), C(d-bz) and C(e-f), so these capacitors do not charge.

Plunger released (bomb released):

Ground connection bz is made so C(c-bz) and C(d-bz) charge from the reservoir C(a-bsp) during the travel of the bomb.

Bomb impacts:

Switch(g-h) operates and C25 fires to complete the ground to the main igniter circuit (glow tube, Sx6, etc).
Switch(c-Sx5) operates and C(c-bz) fires Sx5, removing the ground spring clip connection and thereby removing the ground connection to C(a-bsp).

C(e-f) is charged from C(d-bz) via resistor R(d-e). When the voltage on C(e-f) equals the striking voltage of the glow tube, the main igniter Sx6 fires and the bomb explodes.

Without knowing the resistor values it is not possible to say what the timing values are for this fuze. Given the ratio of C(d-bz) to C(e-f) as exactly 2:1, and that the primary reservoir C(a-bsp) is not used to charge C(e-f) directly (it is actually removed from the circuit and C(d-bz) charges C(e-f) ), then the delay is short, perhaps 0.1-10s, and programmable, proportional to the initial voltage applied from the aircraft. This might suggest the fuze was designed for an armour or bunker piercing bomb, using an accurate electrical variable time delay instead of a pyrotechnic delay pellet.



Tom.

Hi Tom,
I concur with all your readings of the circuit functions. I agree that that the trembler switch "g-f" for C 25 may not function for shure on release, but the forces acting on the bomb when the charging head is torn off, may be sufficient, as the trembler is quite sensitive. Any which way, it takes quite an amount of time after C25 has fired, that enough charge has developed in the 0,4 and the 0,2 microfarad condensers before the striking voltage of the tube is reached. For a short delay, like needed for armour piercing, this would be much too long. The tube in the drawing below igniter SX5, I think, is the "very long delay tube" (VZ tube up to 14 Sec.). This is used in dive bombing attacks, so the plane has enough time to get out of influence radius of the functioning bomb. So assuming that this circuit is the longest delay, the tube timing circuit will be shorter and is independent of any impact influence once it is armed by C25. The attached drawing belongs together with the circuit diagramm. Here an SX6 igniterr is drawn as igniter for the VZ (very long delay) tube, on the left, while besides it on the right the glow-tube igniter is drawn. The C25 is situated in the position of the empty plunger hole in the upper isolation (switch) block. I do now understand the workings of the circuit, but I still can not phatom the reason for this design.
Bellifortis.

 

[Snufkin]

Hi Bellifortis,

Thank you for the additional drawing. It is very informative to see the location of the igniter circuit of Sx6 + glow tube + delay pellet (Verzgerungssatz, I assume), and the ground arming bridge wire C25.

If the ground arming to the glow tube circuit were to be made on the bomb being released, then I reiterate that I should expect the ground connection at f to be made simply by connecting f to bz. Operation of the plunger on release would then reliably connect the ground. The use of the trembler switch(g-h) is for impact arming of the glow tube circuit.

While your second diagram shows the physical arrangement of Sx6 firing a pyrotechnic delay pellet to ultimately detonate the bomb, I am not convinced that the item fired by Sx5 is another pyrotechnic delay for exploding the bomb. It is not a circuit symbol that I have ever encountered, and my interpretation is that the drawing very deliberately shows a ground connection made between bsp and b via an explosive pellet and a spring contact. Impact of the bomb causes an immediate explosive severing of the ground bsp so that the reservoir capacitor is disabled.

The overall time constant determined by the combination of C(e-f), C(d-bz), R(d-e), gives an accurate and programmable electrical delay, t(p), dependent on the initial applied voltage. The pyrotechnic pellet gives a fixed delay t(f). The total delay, after impact, is therefore t(p) + t(f), and the bomb is purely a time delay device. The reason for the design would seem to be just one way of achieving a variable delay.




Tom.