SBB Historic: Schaltplan – two circuit diagrams of the Ce 6/8 III crocodile

New 9Mar2020. Updated 26Dec2023 (Search for “E.432”, 11Jan2023 ([10] and [11] plus typing). Finished for now. Awaiting your comments! This note is in subgroup My Crocodile locomotive pages of group MODELS.

In this note I will try to convey the structure of two circuit diagrams, both from 1925-26. They are Schaltplan of the Swiss “crocodile” locomotive, the beautiful SBB Ce 6/8 III. They are copies, no less spectacular than what they describe, and they reside in SBB History’s Archives & Collections. The originals are gone. But what is an original? This is also discussed.

Thanks to [JC] of SBB Historic for several email exchanges. Without them this note would, first, not have happened at all – as she discovered the drawings in the archive, and second, it would not have been so fun to work with – as she did parallel research and presented many interesting results to me.

But I am myself responsible for what this note is and what it is not! If you find any errors or problems, please comment (below) or mail me! The more I study and write on this blog note, the more I realise how little I know about all the vast branches of technology that spring out from, even the first drawing.

Fold handling of some tables

This blog note uses the Collapse-O-Matic WordPress plugin to handle text folding. In addition to expanding and closing them individually you may here:

Expand All (for searching)
Collapse All

Typical fold

German English
  This text 123456789 will only be found with browser search when the fold is expanded


1924 looking ahead or.. “Hey there!” from 2020?

Narrative style disclaimer

This note would not have seen light if I had found a single electrical drawing of the SBB Ce 6/8 II or III on the web, or in any of the books or magazines (as seen in My Krokis notes (References)). But SBB Historic could help! I paid a small sum and was allowed to publish it – even here.

Drawing 01 (top) and 02 (bottom) compared in size – annotated, overview only

These two drawings are marvels. I am no specialist on this, no historian. I don’t even know if the person who drew them used a drawing standard. When did ANSI, DIN, ISO and IEC standards come into play? Historians! More below.

At first glimpse they are lookalikes. But second glimpse? I will try to find out.

The engineer drawing these diagrams might have loved the Fritzing Computer Aided Design (CAD) tool. Provided there were one for professional locomotive designers, not only electronic circuit boards, which has breadboard, schematic, PCB and code views – all showing different views of the same object. However, a hundred years ago, ink and large paper sheets ruled. And no copying machines. (Update. They certainly had some. See Duplicating machines at Wiki-refs. But, which role did the single(?) original have in this case? Update: When I learned from [JC] that these diagrams are copies, and that the originals are gone, this just proved that history is a discipline in its own sense, far from my well intended reasoning. You are warned! It was good I asked (Q&A) – and got a response.) They had photography, og course. But I guess (again!) that the best way to have a copy was to make a copy. To have one copy, make two, equal – from scratch – and keep one tidy for backup. Even after the helping hand here, this took me more reasoning than you would believe.

Drawing 01 (top) and 02 (bottom) – annotated, overview only

These diagrams are top-down (description, analysis) and bottom-up (specification, synthesis) in one diagram. Even then I see no trace of errors in it, no place where anything has been erased. (Update: I did, on diagram 02. Search for “erased” here). The layout cannot have grown organically as the design went on. The layout is the result of a final design. One thought. It is bright. As simple as that.

  1. One drawing is the circuit diagram, or is main Schaltplan. Maybe wiring plan is a better name. I number it diagram 01 here
  2. The other drawing is an installation, mounting and wiring diagram or Schaltplan für MontageI number it diagram 02 here

In other words: each of these drawings is a full story. Since there are two drawings, are there two stories? I think the answer is no. I think one could actually live without diagram 01, even if it makes the best box type diagram, without the electrical conduit that is added in diagram 02.

About PL_105_00129 01 and 02

The dry facts. The two drawings SBB Historic thought were closest to what I asked for are:

PL_105_00129 Be 6/8 III 13301-13318 (vormals Ce 6/8 III) (1924-1926)

Both drawings are initially approved by the same two persons. Same signatures.

From – Archive & Sammlungen (Archives & Collections).

These drawings are from Maschinenfabrik Oerlikon (MFO), who did the electrical parts of these locomotives. Maschinenfabrik Winterthur (SLM) did the mechanical parts.

  • [01] PL_105_00129_Hauptschaltplan_01.tif – Main diagram (block diagram) (245.5 MB) (Original from SBB Historic, not available here)
    * 14279 * 10219: 6 folds, scanned as unfolded at 300 dpi
    * 121 cm * 86.5 cm ≈ 1.05 m2 or 8.5 * A3 sheets (17 * A4)!
    * 121 cm / 6 folds = 20 cm/fold
    Figures numbers here are not the first figx_ in the file name, but the second _figy_ inside, ie. the serial number of [01] excerpts
    * 01-fig.3 – title and revisions blocks
    * 01-fig.1 – side view. Also see 02-fig.2 (below)
    * 01-fig.2 – main parts
    * 01-fig.4 – transformer and switches
    * 01-fig.5 – brake and drive connections
    * 01-fig.6 – auxiliary circuits
    * 01-fig.7 – main index
    * 01-fig.8 – fully annotated full main diagram (13 MB)
  • [02] – PL_105_00129_SchaltplanFuerMontage_02.tif – Installation diagram – (165,2 MB) (Original from SBB Historic, not available here))
    * 25088 * 7258: 10 folds, scanned as unfolded at 300 dpi
    * 212 cm * 61.5 cm ≈ 1.3 m or or 10.5 * A3 sheets (21 * A3) (25% larger than diagram 01)
    * 212 cm / 10 folds = 21 cm /fold
    * 02-fig.1 – some annotated full installation diagram (11 MB). The original from SBB Historic is not shown in this blog note
    * 02-fig.2 – side views from both drawings
    * 03-fig.3 – fully annotated installation diagram (10 MB)

The sub-points show the pictures I have generated from the corresponding original tif file, which will not be published here.

About sizes

Size in cm = (pixel size of (part of) the 300 dpi scanned picture / 300) * 2.54.

DPI (or dpi) means Dots Per Inch, and one inch is 2.54 cm. This is considered rather low resolution for scanning, but for the huge hand drawn diagrams of this type, 300 dpi is on the spot.

Example. 01-fig.1 (below). It is a crop of 3316(width) pixels by 1206(height). Width = (3316/300)*2.54 = 28.07 cm. Height is then 10.21 cm. Therefore I have named the figure “fig2_sbb_historic_pl_105_00129_hauptschaltplan_01_fig1_locomotive_ce_6_8_28.07×10.21.jpg”. The first “fig2” is the sequence in the note, the second “fig1” is the number in circuit diagram “01”.

Some figures, like 01-fig.3 consist of several parts. These parts are not individually scaled, meaning that the scaling an all parts is the same: 300 dpi.

Studying and navigating the diagrams

My suggestion is to view the drawings in another window. You can do that with your browser. It’s then easier to follow the text here. All files here are JPG/JPEG. These are compressed and may behave slow during navigation. Therefore you may try to download them and open them in some tool (macOS: Preview) and export as TIFF not compressed. Then open that TIFF file, and it should be fast. I think that for such huge files (the largest is about 25000 pixels wide) unpacking a compressed segment still takes some time; I think that’s the reason for navigation not always being smooth when viewing a JPG/JPEG. I also saw that for my original, which is in macOS Pages (next chapter) navigation was really fast!

Production of files

How are pixels and compression amount visible? I took the two original TIFF files that I bought from SBB Historic and converted them to JPG. I saved with compression of diagram 01 as 100% (best, too much!) and diagram 02 as 80% (much more suitable, much smaller file size). Then into Pages, edit as screen layout, with paper sizes equal to the cm-sizes of the originals. Then added transparent fields etc. Then export to PDF as “best”. Then opened in Preview and saved as JPG 300 dpi “best”. Then into GraphicConverter and save as some JPG compression, like 40%. There is almost no visible noise with 40% JPG. Not including the finest JPG layers would look like noise. All downloadable pictures are 300 dpi. In the figure there is a screen clip of three zoomed excerpts of about 180 pixels (180 pixels / 300 dpi) * 2,54 cm/inch ≈ 1.5 cm width of each. The original TIFF (left), the 80% JPG from the TIFF (center) and the final that came from Pages using the 80% JPG and the export and conversion to 40% JPG (right). Press to study the detail.

Always click a picture to come to its original size, or download from the table above. This means you can calculate the paper excerpt sizes from number of pixels. See formula above.

Some terms

I am a little confused of the English here. I am used to electronics, not locomotives. Please mail me to help in my concrete usage in the text. I fear it may not be correct. I am a Norwegian native.

I have been pointed to [8] where there is an extensive terminlogy list in German.

German English?
…Schalter … switch (local?) or … changer (remote?)
Fernschalter [134], [140] remote switch or remote changer or circuit breaker?
Stufenschalter [13] tap changer or step switch or speed switch? How about speed step tap changer? (Two large frames of switches situated by the transformer [7])
Steuerkontroller [150a] Tap changer controller? (Large rotating switch on the driver’s desk that controls Stufenschalter)
Wendeschalter [19] direction changer or direction switch?
Motor [20] Main power motors: electrical motor, motor or engine?

Disclaimer: what to expect from my analysis

I will try to show the different parts of the drawing 01 individually to try to build up some understanding of the full drawing. (This was then not necessary for drawing 02.) Also for myself. I will not, and could never, with my level of competence, do this in any other way than by mentally trying to grasp what’s going on. Any locomotive’s functioning would be too complex for me to even try to analyse. I guess my goals are that I should learn and have fun while I do this. If some of that will come through to you, it would make me happy.

Also, since I have a background in electronics it’s the electrical parts i would emphasize on. The pneumatic and mechanical parts I am even less competent to write about.

Any specialist in this will of course, in addition to seeing flaws in my writing, also see what I have not covered. Luckily, for myself, at least – that hasn’t stopped me from writing. After all, it is the first discussion of the SBB Ce 6/8 III (or II)’s circuit diagrams that I have seen.

According to [WII] there are significant individual differences on theses locomotives. The reference even goes through some of them. I may miss out on some of this detail, even if I will try not to.


My main sources are the German Wikipedia articles about the SBB Ce 6/8 II [WII] first, and SBB Ce 6/8 III [WIII] second, both with chapters The electrical parts. I try to understand what is described in those and map it into these diagrams. Thanks to Wikipedia authors (and Google translate)! Plus, of course note 201:[2] (Eisenbahn Journal, Krokodile). Update Jan2023: see [10].

Drawing 01: Main diagram

The figure numbering sequence is as I made them.

Drawing 01-fig.3 – Title and revisions blocks

Drawing 01-fig.3 – SBB Historic PL_105_00129 Hauptschaltplan. Excerpts. Revision block (left, from lower left) and title block (right, from lower right), height 25.6 cm for both

Compare with Drawing 02 – Title and revisions blocks for drawing 01.

Drawing 01 – Title block

In the figure: right. On the paper: lower right. Part of the heading is mit Nutzbremsung or with regenerative braking. Bringing it up here might indicate that this was important to “sell” inside the company, as it was quite new. I assume that anybody who understood the diagram would have grasped this at first glimpse. More about this exciting way to brake later. (This is also is a selling point for modern, electrical (battery) cars.) We see that this is order 133413. This is a higher number than for diagram 02. I don’t know what “Br7 Lok.” means. First drawn and signed on 27.VIII.25 (27Aug1925). This is the diagram for the road numbers #14301-#14318 as 14301 – 14318, year 1924. So it actually goes for my Märklin 55681 Ce 6/8 III #14305. Nice to know.!

Drawing 01 – Revisions block

In the figure: left. On the paper: lower left. There are two revisions. Korrekturen nach Angabe der Montage ausgeführt or Corrections carried out after specifying the assembly. With initials / signatures.

  • 11.III.26 (11Mar1926) G1. There are several G on the diagram. I don’t know what this means. H.A. are the initials. Same date and initials as diagram 02!
  • 9.IX.26. (9Aug1926). Initial B. Same date and initials as diagram 02!

Electrical wiring legend

All except the last row of the below carry current, even those with dots and dashes:

Line type German English
Semi-thin, solid line Hochspannungsstromkreis High voltage circuit
Thick, solid line Triebmotorenstromkreis Main drive motors circuit
Thick, dashed line Zugheizungsstromkreis Train heating circuit
Thin, dashed line Wechelstrom-Hilfsbetriebstromkreis AC auxiliary power circuit
Thin solid line Gleichstrom-Hilfsbetriebstromkreis (*) DC auxiliary power circuit (*)
Thick dot-dashed-100 line. Thin in the legend, thick in use Wechelstrom-Rückleitungen AC return wires
Thin twodot-dashed-50 line(?) Gleichstrom-Rückleitungen DC return wires
Thick twodot-dash lines (not electrical!)   Frames for functional parts of auxiliary circuit
blocks, like [|A|], [|B|], [|C|], [|D|] and [|E|] in Fig.6

(*) DC comes from a generator, seen as [108] at diagram 01. There also is a battery, of course [111] (see Battery).

A private aside


The first very much outside the theme: My mother and father were 10 in 1925. I have heard that my father’s father Ole Hansen Teig, did some work for Kværner Brug at the time, presumably with the electrification of Norway. From here I learn that somewhat earlier he worked as “monterformann” (assembly supervisor) for the Norsk Hydro AS factory Rjukan Salpeterfabrikker (nitrogen fertilizer production), possibly working with these ovens (furnaces).  All this now is the Rjukan-Notodden Industrial World Heritage Site (here), where there is a photo of the furnace houses at the end. More about the stride around these ovens and the ownership here. Switzerland and Norway both certainly had hydro power to help build the countries. And my father Hans-Jacob Teig, worked on winding transformers and generators for NEBB from 1935-1945. (There is a photo of him as a small boy at Rjukan at 207:[Aside: my father]). NEBB was a company where the Swiss company BBC (Brown, Boveri & Cie) had a share of 50% at time. I love Wikipedia. BBC took over Maschinenfabrik Oerlikon (MFO) in 1970. Observe the person at the generator stator: Fig.X: “Hans-Jacob Teig (left, lower pictures), and photo, at NEBB (Norsk Elektrisk & Brown Boveri A/S), Oslo, ca. 1939. Øyvind Teig (me) at Norsk industriarbeidermuseum (NIA) by NEBB generator at Vemork, Rjukan in 2012. Above: Oerlikon 1928 generators still at museum”. It’s like I can feel my long arm with fingers almost touching these Schaltpläne:

Drawing 01-fig.1 – The locomotive

Drawing 01-fig.1 – SBB Historic PL_105_00129 Hauptschaltplan. Lower left. (excerpt 28.07*10.21 cm)

This is the third time I show this drawing, but here’s some text. But don’t hold your breath, you would suffocate: The two central fan frames are 9*7 mm in the original drawing! This sets the context of the minuteness of the drawing work. Here each fan frame has 9 slot lines plus 4 lines for the frame, altogether 13 lines. 7 mm / (13-1) = 0.6 mm per report for line and white space. The engineer had to use a 0.3 mm nib or thinner. And spill no ink!

I will call the left part for the II-direction, the central part for the box and the right part the I-direction. In the drawing: II is in the read and I is in the front.

Update 21Jun2020: I have used this drawing in a button I made. It’s in note 207 (here).

01-fig.1 aside. Fan frames

The upper and lower frame I define as being a mechanical “out” part. Also, the flaps inside the “window” blinds are also “out” at the lower side (the rain shall not run in), as opposed to the openings between the flaps where the air floats. Counting parts of the frame that are “out”, then the above drawing shows 10 out-parts in the window and 1 out-part for the upper and lower frame = 1+10+1 = 12. This corresponds to the frames that I see on the existing Ce 6/8 II #14253 (p36 of 201:[1]). However, these fan frames of the cabin and transformer hut (box) were new with the III-types crocodiles. I see that my Märklin model 55681 of the Ce 6/8 III #14305 has 1+12+1=14 out-parts while the fantastic, original mechanical drawings (pp 51-54) of 201:[2] the III-version has 1+13+1 = 15 out-parts, if I read the diagram correctly. At p.69 of the same, my model’s original #14305, indeed has 1+12+1 out-slots. Same of the #14305 on 201:[1] p.40. Update: The Wikimedia Commons pictire of #14315 (below) is the best original I have seen of this. It shows 1+12+1 out-slots.

This being said, the layout of the fan frame blinds of the original and my model may not be as prototypical as they could have been! I think there is something with the lowest flap, the air opening and the frame. Disclaimer about this: I am quite unsure! Noted in note 201:Trivia 8.

Update: In the other drawing, 02-fig.1 the side fan frames are 1+8+1 = 10. That diagram is dated 14.X.25 (14Oct1925), just some six weeks after the 01-fig.3. So I assume, one should pay too much attention to this detail. Maybe it’s just some kind of hatching? A comparison with drawing 02 is seen at Drawing 02-fig.2 – The locomotives compared

What I was going to say was that also some mechanical detail are in place in this diagram. Give and take that these are not mechanical drawings. I assume that the number of slots of the fan frame were not settled when it was drawn. Or they thought that nobody, not even in 2020, would check this out.

We shall below see that both drawings are structured topographically.

For the auxiliary circuits functional blocks [|A|], [|B|], [|C|], [|D|] and [|E|], see 01-fig.6 (later).

Drawing 01-fig.2 – Control of motors

In 201:[2] (p.18 – my main source of info here, not all translated) I read in German (and let Google translate it here) that:

Die Fahrgeschwindigkeit wird mit elektromekanisch antriebenen Stufenschaltern geregelt. Sie steuern 20- oder 23-stufig die Stromzufuhr zu den Antriebsmotoren und können Störungsfall auch von Hand betätigt werden.
Auf jedem Motorenpaar sind die zugehörigen, elektropneumatisch steuerbaren Wendeschalter und die zur Kühlung notvendigen Ventilatoren aufgebaut.
The driving speed is controlled with electromechanically driven step switches. They control the power supply to the drive motors in 20 or 23 stages and can also be operated manually in the event of a fault.
The associated electro-pneumatically controllable reversing switches and the fans required for cooling are installed on each pair of motors.

Drawing 01-fig.2 – SBB Historic PL_105_00129 Hauptschaltplan (excerpt 91.5 cm wide) Lower part added (rev.2)

Beware of Electrical wires legend. Legend of my colouring of my added graphics:

[nn] are often just examples. Top black line: Catenary wire. Light blue fields: motors [20], relays [160], direction and brake switch [19], transformer [7], electromechanical [149]. Light blue lines: rods and gears from speed wheel in cabins. Controls secondary power from transformer [13]. Red line: pneumatics (air pressure). Power direction and brake switch [143], [19] – and pantographs [1]. Red decayed fields: main switch controlled by pneumatics [129], [135], [5]. Dotted red line: rods and couplings from handle [134] in cabins [150]. Green fields: in the cabin Fernbetätigung d. Stufenshalter remote control of speed tap changer [150]. Blue and green arrows: I observe that in 046:[18] (p.33, for the Ae 3/6 II, reuse of Stufenshalter tap changer, see below) that the handle by the blue arrow is called Steuerkontroller [150a] driving controller Handrad el. Antrieb electric drive handwheel.  By the green arrow: Handrad Handbetrieb handwheel for manual operation. Red framed boxes: Speed list [150]. Black tilted arrow right bottom: wire for the other motor pair (not seen). Grey horisontal line, bottom: hides lots of the drawing (not seen). All colouring is transparent so that original lines are still visible. The top, left Fahrschaltung part is discussed in the in a later chapter.

Main points. The full diagram (in Drawing 01-fig.7 – Main index (below)) contains a thorough legend, but only the main points are listed here.

Another legend: [nn] without a url is the number used in the circuit diagram. So [1] is the Stromabnehmer pantograph. But [1] as a link, is to Numbered reference 1:

A. Hauptstromkreise
1. Hochspannungsstromkreis
2. Triebmotorenstromkreis
3. Zugheizungsstromkreis
A. Main circuits
1. High voltage circuit
2. Main drive motor circuit
3. Train heating circuit
B. Nebenstromkreise
1. Hilsbetriebsstromkreise

2. Generatorstromkreis
3. Steurstromkreis
4. Beleuchtungsstromkreis
B. Auxiliary circuits (secondary)
1. Auxiliary operating circuits
2. Generator circuit
3. Control circuit
4. Lighting circuit

I assume the following text needs a lot of polishing as I learn more. This repeats some of the legend (above). Observe that since the I and the II-directions are duplicated, many numbers appear twice, like [150].

  1. I have added some coloured lines, circles and arrows to this and the other diagrams. No text is added in any of the diagrams I present, except the SBB History and identification block in the full diagrams 01 and 02. The II-direction is at the left side. It consists of the rear [Hinten], left [Links] and two AC single-phase motors (blue circle). I will discuss them more later. Each of them on 440 kW (kilo-Watt or 1000*Watt) @ 38 km/h. They are connected in series. A double curved, red arrow shows the flexible connection bridge between II-direction and the box. Then the II-direction driver’s cabin with a blue and a red arrows by the two “driving wheels” (?) The box contains the main (primary at 15 kV, 16⅔ Hz) transformer. Its main switch is [135] and [5]. I think it switches the voltage from the pantographs [252] in or out to [253]. But [253] also is available on the roof, for some reason. Maybe to be able to ground it through the [4] switch on the roof? [2] is a knife switch. The transformer’s primary current is read via the serial current transformer, even if it looks more like two resistors [8] L, K. Or even, maybe L, K are two switchable inductors / transfomers?
    The main transformer’s secondary voltage is switchable. Finally, the I-direction driver’s cabin.
    1. Since the Ce 6/8 III has four motors and some other power consumers that together draw about 1809 kW from 15 kV (single phase, where the two wires are the catenary and the rail), the current through the primary’s current transformer’s would be about 1809.000 W / 15000 V = 120A (?). I assume here that all power is burned in the motors, no loss in the transformers etc. Which is rather imprecise, in view of the fact that much of the circuit has to do with cooling fans. The 120A is also depending the power factor cos(ϕ) (Phi is ϕ and is the angle between current and voltage). This is mostly dependent on the stored energy in the coils of the motors and the transformer, but also on whether the locomotive is using power from the top when pulling loads, or delivering power back and up again when braking (below)
    2. I have not been able to figure out the dimension of the 15 kV cables. It depends on temperature and shorting properties etc. But I found that catenary wires would be some 144 mm2. I assume that they might cover more than one locomotive, depending on where the feeding masts are placed. And they are cooled by free air and by the droppers (the vertical wires they hang in). I just assume that one do not have to oversize them. Anyway, r = sqrt (144 mmπ) = 6.8 mm, diameter ⌀ is 2r = 13.5 mm. For a back-of-the-envelope calculation it doesn’t look too bad. The cables on the roof of my Märklin 55681 are about ⌀ 0.5 mm. Times 32 = ⌀ 16 mm. Which is not far away from 13.5 mm. So what is it in real life?
  2. The grey horisontal line at the bottom contains lots of diagram that I removed for this crop. Below it is the bottom part to see where the most important cables would go. The one at the bottom, far right, that seems to go nowhere – goes to the I-direction motors. These:
  3. Also right, not seen, are the I-direction’s two motors. They are equal to the II-direction’s motors
  4. The purple lines are air pressure (pneumatics). This is used push the motor’s direction switches and do the pantographs. The compressor that generates the pressure [47], is not visible here (it is later on), and not drawn as connected to the pneumatics for that sake. Have a look above the curved, double red arrow. You will see the pneumatic cable also cross. It goes from solid tube (copper) to a flexible tube, and even the clamps are drawn! This is what we could call a hybrid diagram!
  5. It’s not even humour that all the bridge cables are drawn as curved down. First, they look like this on the loco. Second, it needs no further explanation. In other words: it makes the diagram more readable. Diagram 02 has a slightly different version (later)
  6. You now understand that the diagram is topographic. In Drawing 01-fig.8 – Fully annotated full main diagram you will see that II-direction is at the left, and the I-direction is at the right sides of the diagram. However, on each of these sides of the diagram, the left and right sides of the locomotive are also shown. Links (left) on the upper part and Rechts (right) on the lower part of the diagram. Here they have chosen not to mirror locomotive topography in the diagram, since Links/Rechts would have the same up/down positions on each sides of the diagram. But the pantographs are on the top, the cabins, transformers and speed switch at the middle etc.
  7. Left [Links] is left. The pantographs are at the top. The drivers’s cabin are at each end of the box. The transformer is in the middle
  8. There are backup systems to handle several failures. If the air pressure falls there is a hand pump. I am not certain whether that pump only has enough for the pantograph circuit. (Aside: In [7] you can see this pump in real use on the Ce 6/8 II 14253. You can even see the spark ⚡ when the pantograph touches the catenary wire again.) There is mechanical backup (steel rods with gears, like [159]) (the blue lines) that connect the two cabins and main transformer. Also for the brakes. The brakes would get activated when the air pressure fell (99% certain)
  9. The motor has 23 steps. See Drawing 01-fig.4 – Transformer and motor steps (below)
  10. The same 23 steps are also used when reversing. There is no gear that may be used to reverse the rotation, so the motors need to get the 16⅔ Hz phase differently applied to stator and rotor. This is done with a switch that is driven pneumatically with air pressure or [19]
  11. Braking
    1. When braking, the motors may deliver power that is fed up to the pantographs. This was already standard for several MFO electrical locomotives, and had been invented by the chief engineer Hans Behn-Eschenburg (1864-1938) (See Wiki-refs, below). This braking system “was a very important factor for the electrification of the Gotthard-line, since it is very steep. And after all, the Krokodil is a Gotthard locomotive” [JC]. The power is fed into via the transformer [7] and coils [23] up to the catenary wires. Hopefully there would be another locomotive that would use that power. I am not certain if they relied on that, or if there were other mechanisms (like phase matters and coils – vector diagrams were matters that they knew everything about at that time) that could make up for a missing locomotive? Or all locomotives brake simultaneously? Observe that this was in 1925! Basic to the solution is the fact that any electrical motor (that converts electricity to rotational moment) also is an electrical generator (that converts rotational energy to electricity and thus would be hard to pull around if that electrical energy is used).
    Observe that this generator or dynamo effect is also present when the motor runs as a motor. It’s called Counter-electromotive force (counter EMF, CEMF), or back electromotive force (back EMF, BEMF). In modern electronic regulators it’s some times estimated, to get the speed of the motor’s rotation
    2.  The produced energy may also be consumed in heating wire resistors [FI], [FII], [FIII] and [FIV]. Wrong: they are the stator coils
    3. There would also be mechanical brakes controlled by hydraulics. I have not studied this yet
  12. I cannot find any Blitz lightning protection coil which they had on the earlier II-models, but which was even removed from them. But there is a Schutzwiderstand protection resistor [5b] that might come in for this purpose. It’s difficult to understand the [5]&[6] switch, but it looks to me like [5b] may be connected in series

Drawing 01-fig.4 – Transformer and motor steps

Drawing 01-fig.4 – SBB Historic PL_105_00129 Hauptschaltplan (excerpt 40.42 * 17.06 cm). Transformer and switches

Beware of Electrical wires legend. Lines containing dots and dashes also carry current!

The transformer has taps on each side, with these voltages: [U1]/[V1] 75V – [U2]/[V2] 132V – to [U3]/[V3] 169V – to [U4]/[V4] 207V – to [U5]/[V5] 264V – to [U6]/[V6] 301V to [U7]/[V7] 358V – to [U8]/[V8] 414V – to [U9]/[V9] 470V. The voltage between each step just tells about the transformer. The voltage between one step to the other is 75V, 57V, 37V, 38V, 57V, 37V, 57V, 56V and 56V for the last up to 470V. But the lowest point, the zero point, is permanently connected to ground, shown as the thick dot-dashed line coming down in the middle of the transformer from the Erdungsschiene earthing bar [100]. (I messed with this for days!) Still we have to think of the transformer as having a long secondary coil with 470V + 470V = 940V. It is this coil that has the taps, and the motors are connected any two places along that coil. They have drawn the transformer as a left side with [Un] positive voltages and the right side has [Vn] negative voltages. This is just some drawing convention. No, they are in opposite phase such that when they form an AC source at each side, the voltages may be added. More later.

Each side of the transformer [7] shows one Stufenshalter step switch, which means there are two step switches [13I] and [13II], and they are independently changeable.

The speed may be switched in 23 steps with electromechanical step switches.  How can we find these steps in the diagram? They are cam-controlled lever mechanisms, controlled by a servo motor, [165]? You can see this by the green rods. A horisontal switch-bar is indexed with (from left) 6, 5, 4, 3, 2, 1, 0, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8 and 7. I am not certain how to interpret that switch. But there also is a relay there to help [160], also connected to the servo motor. The motors get power and consumes power when driving. Since I don’t know how the cam is designed and the diagram does not indicate, I would just have to try.

Then, the steps. Observe that since 75V is the smallest value, when it is taken from each side, the smallest we see is 150V AC. Some are overlapping. Let’s have a look. See table below. In column 2 I have listed all possible steps. Column 3 is just sorted. In the rightmost column is a list of possibly used taps as STEP NUM? Voltages are so similar that all cannot be used. Since the diagram does not indicate how the cam pushes and releases the switches [13II] and [13I] (see top left [U2] and [U1] connected to two switches called (E) and (A). Kind of like a switchboard. There are 6 of those an each side, in groups of 3. The interesting thing is that [U1], [U2] and [U9] on the left side, and [V1], [V2] and [V9] on the right side are each connected twice to the switchboard. I assume this is so that the cam may be designed simpler. I don’t know if the switches are break before make, but I assume so. [15II] and [15I] are Ueberschaltdrosselspule or overshoot choke coil to make the contacts of the switches actually survive, with less high voltage peaks during the switchover. It’s kind of hard to tell from the diagram, with all these open switches – but we see it from 01-fig.5 (below). We will later discuss how a series-wound motor works.

Trafo steps table

1 150V = [U1] 75V + [V1] 75V 150V = [U1] 75V + [V1] 75V 46 1
2 207V = [U1] 75V + [V2] 132V 207V = [U1] 75V + [V2] 132V 88 2
3 244V = [U1] 75V + [V3] 169V 244V = [U1] 75V + [V3] 169V 121 3
4 282V = [U1] 75V + [V4] 207V 264V = [U2] 132V + [V2] 132V 142 4
5 339V = [U1] 75V + [V5] 264V 282V = [U1] 75V + [V4] 207V 162 5
6 376V = [U1] 75V + [V6] 301V 301V = [U2] 132V + [V3] 169V 185 6
7 433V = [U1] 75V + [V7] 358V 338V = [U3] 169V + [V3] 169V 233 7
8 489V = [U1] 75V + [V8] 414V 339V = [U2] 132V + [V4] 207V
9 545V = [U1] 75V + [V9] 470V 339V = [U1] 75V + [V5] 264V
10 264V = [U2] 132V + [V2] 132V 376V = [U1] 75V + [V6] 301V 288 8
11 301V = [U2] 132V + [V3] 169V 376V = [U3] 169V + [V4] 207V
12 339V = [U2] 132V + [V4] 207V 396V = [U2] 132V + [V5] 264V 320 9
13 396V = [U2] 132V + [V5] 264V 414V = [U4] 207V + [V4] 207V 350 10
14 433V = [U2] 132V + [V6] 301V 433V = [U1] 75V + [V7] 358V 382 11
15 490V = [U2] 132V + [V7] 358V 433V = [U2] 132V + [V6] 301V
16 546V = [U2] 132V + [V8] 414V 433V = [U3] 169V + [V5] 264V
17 602V = [U2] 132V + [V9] 470V 470V = [U3] 169V + [V6] 301V 451 12
18 338V = [U3] 169V + [V3] 169V 471V = [U4] 207V + [V5] 264V
19 376V = [U3] 169V + [V4] 207V 489V = [U1] 75V + [V8] 414V
29 433V = [U3] 169V + [V5] 264V 490V = [U2] 132V + [V7] 358V
30 470V = [U3] 169V + [V6] 301V 508V = [U4] 207V + [V6] 301V 527 13
31 527V = [U3] 169V + [V7] 358V 527V = [U3] 169V + [V7] 358V
32 583V = [U3] 169V + [V8] 414V 528V = [U5] 264V + [V5] 264V
33 639V = [U3] 169V + [V9] 470V 545V = [U1] 75V + [V9] 470V 606 14
34 414V = [U4] 207V + [V4] 207V 546V = [U2] 132V + [V8] 414V
35 471V = [U4] 207V + [V5] 264V 565V = [U4] 207V + [V7] 358V 651 15
36 508V = [U4] 207V + [V6] 301V 565V = [U5] 264V + [V6] 301V
37 565V = [U4] 207V + [V7] 358V 583V = [U3] 169V + [V8] 414V 694 16
38 621V = [U4] 207V + [V8] 414V 602V = [U2] 132V + [V9] 470V
39 677V = [U4] 207V + [V9] 470V 602V = [U6] 301V + [V6] 301V 740 17
40 528V = [U5] 264V + [V5] 264V 621V = [U4] 207V + [V8] 414V
41 565V = [U5] 264V + [V6] 301V 622V = [U5] 264V + [V7] 358V
42 622V = [U5] 264V + [V7] 358V 639V = [U3] 169V + [V9] 470V
43 678V = [U5] 264V + [V8] 414V 677V = [U4] 207V + [V9] 470V 935 18
44 734V = [U5] 264V + [V9] 470V 678V = [U5] 264V + [V8] 414V
45 602V = [U6] 301V + [V6] 301V 709V = [U6] 301V + [V7] 358V 1026 19
46 709V = [U6] 301V + [V7] 358V 715V = [U6] 301V + [V8] 414V
47 715V = [U6] 301V + [V8] 414V 716V = [U7] 358V + [V7] 358V
48 771V = [U6] 301V + [V9] 470V 734V = [U5] 264V + [V9] 470V
49 716V = [U7] 358V + [V7] 358V 771V = [U6] 301V + [V9] 470V 1213 20
50 772V = [U7] 358V + [V8] 414V 772V = [U7] 358V + [V8] 414V
51 828V = [U7] 358V + [V9] 470V 828V = [U7] 358V + [V9] 470V 1399 21
52 828V = [U8] 414V + [V8] 414V 828V = [U8] 414V + [V8] 414V
53 884V = [U8] 414V + [V9] 470V 884V = [U8] 414V + [V9] 470V 1595 22
54 940V = [U9] 470V + [V9] 470V 940V = [U9] 470V + [V9] 470V 1809 23

Since the max voltage is 940V and two and two motors are connected in series, each motor gets max 470V. With a Stundenleistung hourly output of 1809 kW it would be /2 = 900 kW per pair. (Continuous output was 1190 kW). The current would be 900,000W / 940V = 960A into the motors-pairs. Assuming ohmic load (cos(ϕ) = 1), which it is not. It’s four inductive motors. The transformer must then deliver max the double = 1920A. For me this is a lot! And this is passed over the flexible connection bridge(?) Or is there some cabling inside? 

Electric locomotives usually have a continuous and a one-hour rating. See Wiki-refs Traction motor, chapter Rating.

(*) Power in kW, total for all four motors. Nothing for heating, cooling fans er other losses! Even assuming that the motor equivalent diagram is a resistor, which it is not! If any motor guy out there want to give me the equivalence diagram for the motors, please do. But still assuming this, continuing using Ohm’s law we have:

R [Ohm] = U [Volt] / Current [Ampere] = 940 / 1920 = 0.49 Ohm

for all motors treated as one resistor. Sounds low to me, but then I’m not used to these extremes like high voltage, high current or low resistance. Or even low impedance, which has to do with both frequency, capacitances and inductances, plus ohmic resistance. I mentioned vector diagrams, that’s where they enter the picture. 0.49 Ohm probably only shows that assuming resistive load is rather wrong. Here’s the formula I have used in column 3:

[Watt] = (U [Volt] * U [Volt]) / Load [Ohm] = (U * U) / 0.49
1809 kW ≈ (940 * 940) / 0.49 (checking the formula)

I read in [3] (p.90-91) that SBB used the same Stufenschalter speed tap changer for the SBB Ae 3/6 II locomotives. Reuse is most often a good idea. Since they are alike, the description of how they work should be valid here as well. See [2] page 32-33. Even there they say that it is too complex to describe in a magazine.

Drawing 01-fig.5 – Motors, driving and regenerative brake circuit

Drawing 01-fig.5 – SBB Historic PL_105_00129 Hauptschaltplan (excerpt 84.6 cm). Motors, driving circuit, regenerative braking circuit and transformer

(Update Jan2023: [10] by Hans E. Wettstein (2022, in English) describes (from his ref. 3) some of the diagrams from [11] by Hans Behn-Eschenburg (1919). Wettstein writes on page 14 that “A detailed article published in 1919 described the electric scheme and tests with a 2250 HP locomotive (type Be 4/6 number 11301, later changed to 12301) [3]. This locomotive did not yet have the appearance of a “Crocodile”. The tests carried out with this locomotive included the first regenerative brake system for this kind of electric system.“)

The figure above shows how fantastically educational the drawing is. I have again assembled several parts of it into one. The middle drawing Fahrshaltung, driving connections, has been moved from top, left. Bremsschaltung, braking connections, has been moved from top, right. To the right, the transformer part [7], you have seen before. The left part contains the motors [20] and direction brake switch [19]. [21] is a resistive shunt (resistor) for the helper magnet coils.

I have also placed the a copy of the primary coils of the transformer above the secondary windings from Bremsschaltung to the catenaries. This is to hint at the fact that the energy flows that way, “up” during braking or “down” during driving. The primary coil was in 1925 drawn too small on purpose. The primary coil has, on each side of [L7], 7500V / 470V = 16 times more turns than the secondary. The primary is, electrically, much “longer”. But this has not been their point. Everybody knew this. The engineer has instead concentrated on showing the transformer’s taps and used the paper’s real estate for those.

The motors are AC single-phase motors, as discussed to the least detail in chapter 6 of [4] (quite theoretical). One-phase system was introduced early in the last century after they had tested three-phase with two catenary wires (plus the rail as the third) in the Simplon tunnel.  (Update 11Dec2023. See Three-phase AC railway electrification at Wiki-refs, plus the Roco model of the Italian State Railway‘s threephase “trifase” E.432 FS locomotiv, Roco here and German Wikipedia here. These machines were built as late as 1928, and they stayed until 1976, running in the ever imploding Italian trifase net. With three phase motors, fine scale control of the speed was not possible. But the pantographs themselves would functionally look like those I remember from the trolley buses in Oslo (1940-1968). But these were powered with DC, like the trams.) The Simplon tunnel stayed like this until 1930, when the system elsewhere had become 15 kV, 16⅔ Hz. It seems to have been the AC single-phase commutator/collector motor that caused this transition. Single-phase is one catenary wire and one rail return line. (Uncertain: Even as of today this motor type is much used in locomotives, because of self-turn-off semiconductor devices like gate turn-off (GTO) thyristors and insulated-gate bipolar transistors (IGBT). Maybe this goes for multi-phase AC motors..)

The Wikipedia article on Universal motors is perhaps an easier read (Wiki-refs). New to me is that these motors will run on both DC and AC. Thinking about it, it shouldn’t be new to me, since my old Märklin analogue locos run on both! I haven’t converted any of them to digital, so they are mostly for the shelf. I don’t know how old I was when I first tested this with a couple of 4.5V flat-pack flashlight batteries. I tested it right now, my oldest 3000, however the 1962 version, starts to run at 8V AC from the transformer. I have retired the blue transformer and bought the newer egg coloured transformer. But the loco just as easily starts at 8V DC from a regulated power supply. Universal motor! I had almost forgotten the lovely smell… Therefore they are also called series-wound brushed DC motors. From the above article I quote:

Rail traction
Universal motors also formed the basis of the traditional railway traction motor in electric railways. In this application, the use of AC to power a motor originally designed to run on DC would lead to efficiency losses due to eddy current heating of their magnetic components, particularly the motor field pole-pieces that, for DC, would have used solid (un-laminated) iron. Although the heating effects are reduced by using laminated pole-pieces, as used for the cores of transformers and by the use of laminations of high permeability electrical steel, one solution available at the start of the 20th century was for the motors to be operated from very low frequency AC supplies, with 25 and 16⅔ Hz operation being common.

Another source is the Wiki-refs Traction motor article. Since the rotating and fixed parts are connected in series, they are called series-wound. I don’t know how many poles these motors have. But on SBB Be 4/6 (four motors of max 375 kW each) I infer in [3] (p.42) that these motors must be of about the same design:

Der geregelte Fahrstrom wurde den vier Fahrmotoren zugeführt. Bei diesem handelte es sich um fremdventilerte, zwölfpolige Einphasen-Reihenschluss-Kollektormotoren mit Kompensations- und geshunteten Wendepolwiklungen. The regulated traction current was fed to the four traction motors. This was an externally ventilated, twelve-pole (12-pole) single-phase series collector motor with compensation windings and shunted reversing pole windings.
Die beiden Fahrmotoren eines Triebdrehgestelles ware dauernd in Serie Geschaltet. The two traction motors of a powered bogie would be continuously connected in series.

There is a Wiki-refs Compensation winding article. Also see the translation of the German Kompensationswicklung article.

Left after my grandfather I have a thick book about electricity and magnetism from 1908 [5]. There is nothing in it about the compensation winding, but arching of the brushes is discussed over several chapters. Also, in a 1915 book [6] there is no such thing. At some time the idea that having a small current generated by an extra winding in the stator, in an opposite field, close to the rotor, could counteract arching of the brushes, as the the commutator/collector with lots of connected coil ends rotates/passes by. There is a rather good picture of this in The biggest motor is in Dresden (below). The compensation windings are connected in series with the rotor. I can see no trace of them in the diagram, so I assume this is a permanent connection inside the motor. I also read that “Compensation windings are usually used in large electrical machines that also have a reversing pole winding and are operated with different loads.”

And reverse pole windings. But from 01-fig.5. I see that these also are connected in series, not shunted (in parallel) as suggested in the above table. I will come back to them. But I am 99.9% sure that these are the “grey” reversing windings: [FI-EI], [FII-EII] (in 01-fig.5, above) per motor, seen as [FIV-1], [FIV-2] plus [FIII-1] and [FIII-2] (in Fig.7, below). The [18I] and [18II] are Stromwandler für Triebmotor – some type of current transformers, I think, for the drive motor. These are located in the transformer box on the diagram. For Fahrschaltung there is one half of them in series with the motor circuitry. For Bremsschaltung it looks like they are some kind of current transformer where the secondary parts add their current and feed (or get fed) from the stator coils [FIV]/[FIV] – [FIII]/[FIII] – [FII]/[FII] and [FI]/[FI]. One thing is to see on a diagram how things are connected. Another matter is to find out why. I think I stop here, because I would need some feedback from somebody on this. However, even if this remains unexplained, there is still more to write about. And I admit, there is much back and forth, up and down here now. My narrative style is “stream of consciousness”, for the good and bad about it.

01-fig.7 – Two motors, coarse circuit diagram

I have tried to show in 01-fig.7 how the motors are connected, inspired by the simplified diagrams of [2] (p.29) – even if the locomotive they study there is the SBB Ae 3/6 II which did not have the complicating regeneration brake, (except for #10401 for some years, more below).  The Fahrschaltung and Bremsschaltung also show this very well, but here I have tried to follow the wires, as I have done in the left part of 01-fig.5, and made a diagram with electronics circuit diagram editor iCircuit. It does not have symbols for all I needed, but I hope I still get the point across. iCircuit have me use [223_] and [223], but in the below I drop the underscores.

The (drawn at 45°) rotors (or armatures) [20] are connected in series between [223]-[216]. The stator (or field) magnets are two pairs, across the two motors. One [223]-[209] and one [210]-[209]. The helper magnets are connected in series per motor with no common points: [207]-[202] and [204]-[205]. I must find out what this helper magnet does one day. Help(?)

From 01-fig.5 we see that the stators are called [CIV] and [CIII]. Each of them consists of two magnets, connected in series, like [CIV] = [CIV-1]+[CIV-2] across the two motors. In 01-fig.5 we also see that all of these are always connected in series, both for the Fahrschaltung motor-as-motor and for the Bremsschaltung motor-as-generator. Therefore I added the 940V AC source and connected it to this all-in-series connection. In real life, the helper magnets [FIV-1]-[FIV-2] and [FIII-1]-[FIII-2] are also connected into this circuit, as seen in Fig-6.

Since almost every connection point is brought up to the Wendeschalter reversing switch (or changer?) [19], then it’s possible to rearrange the connections for changing direction or braking. Like a bunch of Lego bricks can build almost anything.

The Wendeschalter reversing switch seems to be used for switching between running in the I and the II-directions. In addition I have a feeling that braking downhill is the same as switching into the opposite direction and call that braking. I am was uncertain, because if this were the solution then I don’t think pushing cars uphill would be possible? But of course it’s like this: Electric motors, when used in reverse, function as generators and will then convert mechanical energy into electrical energy. …. For a given direction of travel, current flow through the motor armatures during braking will be opposite to that during motoring. Therefore, the motor exerts torque in a direction that is opposite from the rolling direction (Wiki-refs: Regenerative brake) 

I think that in [WII] they are close to the answer about the switch. I had to help Google translate some.

Elektrische Nutzbremse
Die Ce 6/8II besassen eine elektrische Nutzbremse (Rekuperationsbremse), welche beim Bremsen die elektrische Energie der als Generatoren wirkenden Fahrmotoren in die Fahrleitung zurückspeist. Zur Einleitung der elektrischen Bremsung musste zuerst der Stufenschalter bis auf Null ablaufen. Danach konnte der Wendeschalter von «Fahren» auf «Bremsen» umgelegt werden. Dann konnte der Stufenschalter wieder aufgeschaltet werden. Eine Fehlbedienung der Nutzbremse führte zum folgenschweren Unfall von Wädenswil im Jahre 1948
Electrical brake
The Ce 6/8 II had an electric useful brake (regenerative brake), which feeds the electrical energy of the traction motors acting as generators back into the catenary when braking. To initiate electrical braking, the speed tap changer had to run to zero. Then the reversing switch could be switched from «driving» to «braking». Then the tap changer could be switched on again. Incorrect operation of the service brake led to a serious accident in Wädenswil in 1948.

I am still not there. (Reading it over, when I have understood it, the above is rather clear..) Does the direction switch have driving-I and driving-IIplus a third which is braking? But each cab has its own ahead direction, and one reverse – and they are opposite. Does this enter the picture here? I must search the literature and the diagrams for the driving and braking switches, if they exist. I have a thorough description of the Führerstand driver’s desk of the SBB Ae 3/6 II, but it didn’t have regenerative braking (except for #10401, below). But then I finally found this in 201:[2] (p.20). In the German text I have also added some red text:

Die Bedienung der Nutzstrom bremse bei der Ce 6/8 II ist unkompliziert: Beim Einfahren ins Gefälle stelltder Lokführer den Stufenschalter auf „Null” und anschließend den Wendeschalter [19] von „Fahren” auf „Bremse vorwärts”. Durch Drehen des Steuerhandrades am Führertisch leitet er dann die Bremsung ein und reguliert in der Folge die für die gewünschte Geschwindigkeit erforderliche Bremsleistung. Identisch zum Motorbetrieb ist auch sie mit 20 oder 23 Stufen sehr fein abgestimmt. Nun arbeiten die Fahrmotoren [20] als Wechselstrom-Generatoren und liefern die dabei erzeugte Energie über Bremsdrosselspulen [23] an den Transformator, von wo sie über den Pantografen in die Fahrleitung eingespeist wird. The operation of the useful power brake on the Ce 6/8 II is uncomplicated: When entering the (downhill) slope, the train driver sets the speed tap changer to “zero” and then the reversing switch [19] from “driving” to “brake forward“. By turning the control wheel on the driver’s table braking and subsequently regulating the braking power required for the desired speed. Identical to the motor operation, it is also very finely tuned with 20 or 23 steps. Now the traction motors [20] work as alternating current generators and deliver the energy generated to the transformer via brake choke coils [23] , from where it is fed into the overhead contact line via the pantograph.
Der Wendeschalter dient sowohl zum Fahrtrichtungswechsel als auch zum Umstellen vom Motorbetrieb auf die elektrische Bremse. The reversing switch is used both to change the direction of travel and to switch from engine operation to the electric brake.

I wonder if or how this could be seen in the circuit diagram, or if those words are needed?

This Wendeschalter reversing switch is a marvel in itself. Like the Führertisch cabin control desk. Like the Stufenshalter speed tap changers. Like everything. I find several pictures and description of some brothers, for other locomotives, as in [2] and [3]. We have, like elegant computer architectures. But we stand on someone’s shoulders.

The Wiki-refs: Regenerative brake (very interesting!) article also pointed out an important matter, namely that the regenerative braking effect drops off at lower speeds, and cannot bring a vehicle to a complete halt reasonably quickly with current technology. (28Mar2020)

When I studied the driving and braking diagrams I was impressed by their appearing simplicity. But there is Ohm’s law in them. Current / voltage / frequency phase vector diagrams. Trial and error. All parts take part in the final goals.

The Wiki-refs: Regenerative brake article also explains how the motors would be switched to go from Fahrshaltung running to Bremsschaltung braking – I had added som text in [red]. Also read the Wiki-refs Armature article. I think the armature in this case is the rotating part, and the field is the fixed parts.

During braking, the traction motor connections are altered to turn them into electrical generators. The motor fields are connected across the main traction generator (MG) [the rotors like [20III] are always connected in series with the stator like [CII], as motor and as generator, see 01-fig.5] and the motor armatures are connected across the load. [The helper magnets like [FIII] are moved from the motor circuit to the generated output]. The MG now excites the motor fields. The rolling locomotive or multiple unit wheels turn the motor armatures, and the motors act as generators, either sending the generated current through onboard resistors (dynamic braking) or back into the supply (regenerative braking). Compared to electro-pneumatic friction brakes, braking with the traction motors can be regulated faster improving the performance of wheel slide protection. (28Mar2020)

I learn in [3] (page 93-94) that SBB added regenerative braking to a single one of the SBB Ae 3/6 II (#10401, picture at SBB Historic on Wikipedia, below). But the regenerative braking parts were removed in 1928. Those locomotives were running on the Flachland flatland, but the crocodiles were running on the Gotthard-line that was steep. That being said, as already mentioned, I assume that any locomotive on the same catenary’s electrical circuit would brake for those with regenerative braking by consuming the electric energy delivered during braking? How wide an area did such a circuit cover? How many runningother locomotices were needed?

Drawing 01-fig.6 – Auxiliary circuits

Drawing 01-fig.6 – SBB Historic PL_105_00129 Hauptschaltplan (excerpt 62.5 cm). Auxiliary circuits

Nebenstromkreise auxiliary circuits functional blocks. The Steuerstromkreise control circuits and Hilfbetriebsstromkreise auxiliary circuits also have some functions here. These blocks are shown as two dot-dash lines. I have shaded each as transparent green. This list is seen in 01-fig.1 (above):

[|A|] Normal Schalttafel in Führerstand I Normal control panel in driver’s cab I
[|B|] Normal Schalttafel in Führerstand II Normal control panel in driver’s cab II
[|C|] Normal Schalttafel für Wechselstrom Normal switchboard for alternating current
[|D|] Normal Schalttafel für Gleichstrom Normal switchboard for direct current
[|E|] Schalttafel für Relais Switchboard for relays

I will start with what I consider being the most interesting block: [|E|] switchboard for relays. Also this diagram is quite crammed, but it is still possible to follow. Anyone wanting to flatten it out in a modern tool? Or by hand, like Franz Eberhard did in 1963/1964 for the SBB Ae 3/6 II locomotive [2] (magazine by him and Hansueli Gonzenbach).

  1. Shorts or other problems might cause overcurrent. This should not cause other parts to lose power. There are several Maximalstromsrelais:
    1. [78] Maximalstromsrelais für Haupstrom – Maximim current relay for main power. Follow wire (116) from [5a] Stromwandler für Maximumsstromkreis current resistor for overvoltage detection to [78] 2. [80] Maximalstromsrelais für Triebmotor – Maximum current relay for main drive motors
    3. [84] Maximalstromsrelais für Zugheizgerät – Maximum current relay for train heaters
  2. I think that this would cause the locomotive to switch off the power (and perhaps turn on the brakes) if the catenary voltage is lost:
    1. [86] Nullspannungsrelais für Hauptschalter – null voltage relay for mains switch
    2. [85] is in [|D|] and is the Sicherung fuse for the above
    3. [182] is in [|D|] and is Schalter für Nullspannungsrelais für Hauptschalter –  Breaker for null voltage for mains switch
  3. Blocking relay I must study to see what the blocking relay does:
    * [87] Blockierrelais – blocking relay. I can see with [6] goes up to several parts, including [129] Fernbetätigung für Stromabnehmer, remote control for pantographs. So I assume this function will indeed block some crucial function. Update: I found this:

In [2] (p.21) I found the below about the SBB Ae 3/6 II, but I assume that the function would be about the same for our locomotive. From the description I assume that this may have been added to avoid ending up with a situation where the locomotive had unpowered itself, but there would still be 15000 Volt on the catenary wires? This sounds like a very dangerous situation for the locomotive personnel, should they leave the cabin and try to do something on the loco. I wonder what fatal accident(s) may have been the precursor to this.

Der Stromwandier zum Blockierrelais
Der spezielle Stromwandler auf dem Lokomotivdach bei den Lokomotiven 10401-10450 sowie der auf den Maschinen 10451-10460 im Hauptschalter eingebaute Auslösestromwandler speisten das Blockierrelais. Dieses verhinderte bei einem heftigen Kurzschluss die Auslösung des Hauptschalters durch das Maximalstromoder Nullspannungsrelais so lange, bis die Fahrleitung durch den Streckenschalter im Unterwerk abgeschaltet wurde. Stellte der Lokomotivführer ein Ansprechen des Blockierrelais fest, so durfte die Maschine auf keinen Fall ein weiteres Mal unter Spannung gesetzt werden.
The current transformer to the blocking relay
The blocking relay was fed by the special current transformer on the locomotive roof of the 10401-10450 locomotives and the tripping current transformer built into the main switch on the 10451-10460 machines. In the event of a violent short circuit, this prevented the main switch from being triggered by the maximum current or zero voltage relay until the overhead line was switched off by the line switch in the substation. If the locomotive driver noticed that the blocking relay had responded, the machine could under no circumstances be energized again.

Battery There is a generator circuit [B2] that contains a generator [108] and a battery [111]. If you open the Main index table (below) and do a search on “battery” you will see that there are more pieces in that circuit. I have not been able to find out about the voltage. I can count 8 elements per battery unit, 16 in the series connection. If the battery were of lead–acid construction, the voltage would be 16 * 2.1V = 33.6V. If the battery were a nickel–cadmium type the voltage would be 16 * 1.2V = 19.2V. I assume lead-acid.

Drawing 01-fig.7 – Main index

Drawing 01-fig.7 – SBB Historic PL_105_00129 Hauptschaltplan (excerpt 65.2 cm). Main index

The main points were listed in an earlier table (Main points). I was in doubt whether to take the time to make this table. But then I discovered how much I learned. Just let yourself slide down the rightmost column (oder die mittlere Spalte, wenn Sie ein deutscher Leser sind) and discover that you cannot stop!

See Some terms (it’s a kind of disclaimer of my somewhat helpless English terminology).

Standardized nomenclature? In [2] (for the SBB Ae 3/6 II) there are diagrams that seem to use the same nomenclature as here. I assume that this may be why some of the numbers in the range are not used; that they are used for something that’s not present on the Ce 6/8 III here. May this have been some kind of international standard? IEC seems to have started already in 1909. See Q&A p.8.

Main index table (diagrams 01 and 02)

Thanks, Andreas und Anna for help with finding out what the German abbreviation d. stands for. Here it is der or des, the latter a genitive form. Some times the word has been cut at the end with a point . Observe that ending s in German is singular genitive, not plural!  And for [150] Fernbetätigung des Stufenschalter (Remote control of tap changer) it is not a missing s but simply German genitive plural. (I assume that the Stufenschalter is seen as a two-part piece). (Thanks, [JC])

Main index 1-20

[A] Hauptstromkreise Main circuits
[AI] Hochspannungsstromkreis High voltage circuit
[1] Stromabnehmer Pantograph
[2] Trennmesser Knife switch
[4] Erdungsschalter Ground circuit breaker
[5] Hauptschalter Main switch
[5a] Stromwandler für Maximumsstromkreis Current transformer for overvoltage detection circuit
[5b] Schutzwiderstand Protection resistor
[6] Hochspannungseinführung Glans for high voltage cables
[7] Stufentransformator Step transformer, speed transformer, main transformer
[8] Stromwandler für Messinstrumente Current transformer for instruments
[A2] Triebmotorenstromkreis Main drive motor circuit
[13] Stufenschalter Speed step tap changer
[13a] Funkenlöschschalter ⚡Spark extinguishing switch or breaker
[13b] Funkenlöschspule ⚡Spark choke coil
[15] Ueberschaltdrosselspule Switchover choke coil
[18] Stromwandler für Triebmotor Current transformer for the main drive motors
[19] Wendeschalter Direction switch or breaker, also used for ahead with regenerative braking
[20] Triebmotor [20I], [20II], [20III], [20IV] Main drive electrical motor (or engine?)

Main index 21-48 (Up)

[21] Ohm’scher Hilfspotshunt Ohmic (resistive) helper magnet coil shunts
[22b] Induktiver Hilfspolshunt Helper magnet inductive coil shunt
[23] Bremsdrosselspule Braking coil
[30] Ohm’scher Zusatzwiderstand Ohmic (resistive) additional resistance
[A3] Zugheizungsstromkreis Train heating circuit
[32] Heizhüpfer Heating accessory
[32a] Funkenlöschspule ⚡Spark quenching coil
[33] Stromwandler für Zugheizung Current transformer for train heating
[35] Heizkupplung (für Zugheizungstromkreis) Train heating socket (in each end of the loco). Follow thick, dashed wire (184)
[B] Nebenstromkreise Auxiliary circuits (secondary)
[BI] Hilfsbetriebsstromkreise Auxiliary operating circuits
[41] Hauptsicherung für Hilfsbetriebsstromkreis Main fuse for auxiliary operating circuits. In block [|C|]
[42] Umschalter für Depotanschluss Switch for depot connection
[43] Steckdose für Depotanschluss Socket for depot connection
[44] Sicherung für Kompressormotor Fuse for compressor motor
[45] Umschalter für Kompressormotor Switch for compressor motor
[47] Kompressormotor Compressormotor
[48] Ohm’scher Hilfspolshunt Helper magnet resistive shunt

Main index 50-73 (Up)

[50] Kompressorautomat Compressor automat
[51] Sicherung der Motoren für Ventilatoren,
Oelpumpe und Generator
Fuse for motors for fans, oil pumps and generators. In block [|C|]
[52] Schalter do. do. Switch for the above
[53] Motor des Triebmotorventilator Ventilatormotor for main drive motor
[54],[59] Ohm’scher Hilfspolshunt Helper magnet resistive shunt
[58] Motor für Oelpumpe, Dynamo und Oelkühlanlage Motor for oil pump, dynamo and oil cooling equipment
[61] Hüpfer zum Motor für Oelpumpe etc. Electro-pneumatic pressure control valve (hopper?) for the motor for oil pump etc.
[65] Umschalter für Fusswärmeplatten Switch for foot warmer plates
[66] Fusswärmeplatten Foot warmer plates
[67] Sicherung des Führerstandheizgerätes Fuse for cab heater
[68] Umschalter des Führerstandheizgerätes Switch for cab heater
[69] Führerstandheizkörper Driver’s radiator
[70] Schalter für Oelwärmeplatte Switch for oil heating pan
[71] Oelwärmeplatte Oil heating pan
[72] Sicherung für Messapparate Fuse for meters
[73] Vorschaltwiderstand zum Voltmeter
für Fahrleitungsspannung
Measuring resistance to voltmeter for catenary voltage

Main index 74-111 (Up)

[74] Voltmeter für Fahrleitungsspannung Catenary voltage voltmeter
[75] Steckdose für Spannung (220V) Socket for 220V AC
[76] Wattstundenzähler Watt-hour meter
[77] Ampèremeter für Hauptstrom Amperemeter for main current
[78] Maximalstromsrelais für Hauptstrom Maximum main current circuit breaker
[79] Ampèremeter für Triebmotoren Amperemeter for drive motors
[80] Maximalstromsrelais für Triebmotor Maximum drive motor current circuit breaker
[81] Sicherung zum Voltmeter für Zugheizung Fuse for voltmeter for train heating
[82] Vorschaltwiderstand zum Voltmeter für Zugheizung Measuring resistor for voltmeter for train heating
[83] Voltampèremeter Voltamperemeter
[84] Maximalstromsrelais für Zugheizung Maximum current circuit breaker for train heating
[85] Sicherung des Nullspannungsrelais für Hauptschalter Fuse for null-voltage relay for main switch
[86] Nullspannungsrelais für Hauptschalter Null-voltage relay for main switch. Fuse [85], switch is [182]
[87] Blockierrelais Blocking (interlock?) relay
[92] Ohm’scher Anlasswiderstand Ohmic start resistor
[B2] Generatorstromkreis Generator circuit
[108] Generator Generator
[110] Sicherung des Generators Fuse for generator
[111] Batterie Battery

Main index 112-140 (Up)

[112] Batteriesicherungen Fuse for battery
[113] Batterieschalter Battery switch
[116] Voltmeter für Batterie Voltmeter for battery
[118] Sicherung des Oelbecherwärmers Fuse for oil pan heater
[119] Schalter für Oelbecherwärmer Switch for oil pan heater
[120] Oelbecherwärmer Oil pan heater
[B3] Steuerstromkreis Control circuit
[126] Schalter für Steuerstrom Switch for control circuit power
[127] Sicherung für Steuerstrom Fuse for control circuit
[129] Fernbetätigung für Stromabnehmer Remote control of pantograph
[129a] Verriegelungskontakt für Steuerstrom Interlock contact for control circuit
[129b] Auslösekontakt für Hauptstrom Tripping contact for main current
[134] Fernschalter für Hauptschalter Remote switch for main switch
[135a] Aüslösespule des Hauptschalters Release coil for main switch
[135b] Sperrscheibe Locking wheel
[135c] Unterbrechungskontakt für Hauptschalter Interrupt contact for main switch
[140] Fernschalter für Wendeschalter Remote switch for reversing switch

Main index 143-165 (Up)

[143] Elektropneumatisch Antrieb des Wendeschalters Three electropneumatic valves for reversing switches
[143a] Unterbrechungskont des Wendeschalters Three solenoids for [143]
[148] Umschalter für Hand beziehungsweise elektrische
Antrieb des Stufenschalters
Switch for manual or electric drive of the speed steps tap changer
[149] Kupplung für Handsteuerung Gears for manual control of tap changer
[150] Fernbetätigung des Stufenschalters Remote control of tap changer
[150a] Steuerkontroller des Stufenschalters Tap changer controller? (Large rotating switch on the driver’s desk that controls Stufenschalter)
[155] Verriegelungskontakt für Stufenschalter Interlock contact for speed tap changer
[156] Verriegelungskontakt für Wendeschalter Interlock contact for direction switch
[158] Stufenschaltermotor Motor for speed tap changer
[159] Widerstand für Stufenschaltermotor Resistor for [158]
[160] Relais für Stufenschaltermotor Relay for [158]
[160a] Relais für Aufschaltung d. Stufenschaltermotor Relay to activate(?) [158]
[160b] Relais für Abschaltung d. Stufenschaltermotor Relay to stop [158]
[162] Sperrmagnet mit Einschaltkontakt Locking magnet with closing contact
[165] Hilfswalze für Antrieb des Stufenschalters Auxiliary roller for driving the tap changer

Main index 169-200 (Up)

[169] Fernschalter für Heizhüpfer Remote control of heating accessory
[170] Elektropneumatisch Antrieb des Heizhüpfers Electropneumatic valve for heating accessory
[171] Verriegelungskontakt des Heizhüpfers Interlock contact for heating accessory
[182] Schalter für Nullspannungsrelais für Hauptschalter Switch for null-voltage relay for main switch
[B4] Beleuchtungsstromkreis Lighting circuit
[188] Beleuchtungswiderstand Resistance for lighting
[189] Sicherung der Beleuchtung Fuse for lighting
[190] Umschalter für Beleuchtung Switch  for lighting
[193] Beleuchtungsregler Lighting regulator
[194] Sicherung der Lokomotiv-Laternen Fuse for locomotive headlights
[195] Schalter für Lokomotiv-Laternen Switch for locomotive headlights
[196] Steckdose für Lokomotiv-Laternen Socket for locomotive headlights
[197] Lokomotiv-Laterne Locomotive headlights
[198] Sicherung der Führerstandlampen Fuse for lamps in driver’s cab
[199] Schalter für Führerstandlampen Swicth for lamps in driver’s cab
[200] Führerstandlampen Lamps in driver’s cab

Main index 201-208 (Up)

[201] Sicherung der Innenlampen Fuse for lamps in trafo-part of central box
[202] Schalter für Innenlampen Switch for lamps in trafo-part of central box
[203] Innenlampe Lamps in trafo-part of central box
[204] Steckdose für Handlampe Socket for hand lamp
[205] Handlampe Hand lamp
[208] Steckdose mit Stecker Socket with plug
Up to Main index table. → TO TOP

Wire numbering ranges (diagrams 01 and 02)

There also is a nomenclature for labelling wires with numbers. This is so nice. If you had asked me before I started studying this circuit diagram, I’d say they did not have that sort of convention in 1925. But they had lots of wires, so why shouldn’t they have a system for numbering them?

(1) – (30) Steuerleitungen Speed switch tap changer wires
(61) – (71) & (75) Motorgenerator Batterie Motor-generator and battery
(81) – (94) Beleuchtungsleitungen Lightning wires
(111) – (129) Messleitungen Measuring wires
(141) – (152) Depotanschluss, Kompressor, Ventilator und Oelpumpenmotor Depot connection, compressor, fan and oil pump motor
(171) – (176) Führerstandheizung Oelwärmeplatte Driver’s cabin heating oil heating pan
(181) – (184) Zugheizung Train heating
(201) – (241) Triebmotoren Main drive motors
(251) – (255) Hochspannung High voltage

Now, for diagram 02, continue at Drawing 02 – Main index addendum.

Drawing 01-fig.8 – Fully annotated full main diagram

Drawing 01-fig.8 – SBB Historic PL_105_00129 Hauptschaltplan (full 121 * 86.5 cm). Annotated with transparent fields by Øyvind Teig. Signed in red (Press for more pixels 13 MB)

Finally 01! Press the picture to see it in width 14291 pixels (13 MB). (14291 pixels / 300 dpi) * 2.54 = 121 cm wide in real. Observe that the original tiff-file from SBB Historic is not shown in this blog note.

Now, is this dry engineering or a piece of art? Or both?

This is the first time the motor and speed switch in the I-direction is shown in this note.


  1. In 01-fig.5, the secondary coils [7], in the Fahrshaltung and Bremsschaltung parts, are drawn with taps. However, these taps are probably meant only to show that there are taps, since they don’t correspond to the correct number, as discussed above and seen in the rightmost part of 01-fig.5
  2. Also, in the topmost, right part of the [7] there, its next to the top dot connection is missing
  3. In the main index (Fig.7) they have forgotten to write a 2 in the column to the left of Generatorstromkreis. This is what is called [B2]. This os the same in diagram 02.

Drawing 02: Installation diagram

Drawing 02-fig.1 – Some annotated full installation diagram

Drawing 02-fig.1 – SBB Historic PL_105_00129_SchaltplanFuerMontage (full 212 * 61.5 cm). Annotated with transparent fields by Øyvind Teig. Signed in red (Press for more pixels 11 MB)

This diagram is even more fantastic! Not one area of it shows any sign of having to draw fast in fear of running out of space. It is much more complex than diagram 01, so this is a treat. The area is two A3 sheets larger than diagram 01. The diagram’s real estate seems to have been very well planned before the first line was drawn. I can see one example of erasing – a table where the contents of three elements of a row has been erased (just the the left of the Führerstand I box), but I think that’s about all.

Drawing 02-fig.2 – The locomotives compared

Drawing 02-fig.2 – SBB Historic PL_105_00129 (upper) 01 Hauptschaltplan (main diagram) and (lower) 02 SchaltplanFuerMontage (installation diagram) (Press for more pixels)

This may be even more pedantic than the rest of this note. However, I wanted to find some detail that were equal on both diagrams. Looking at the figure I found the side views to be very equal. I think that since they are that much equal, then the drawer must have had a template that he placed underneath the drawing paper (if it were translucent). Alternatively, by the paper and then he used a parallelogram mechanism to copy the drawing across. I had to expand the lower scan by 0.1 mm., which isn’t even worth mentioning. But there are differences, see blue arrows. Like the brakepads on the II-direction (left), and the fan frames. Also see 01-fig.1 aside. Fan frames. And the hatching on the II-direction (left), short front. Also, the rightmost door handle bar.

In other words, they must have have had an agreed upon template, and they have copied from it by a very steady hand.

Drawing 02 – Main index addendum

Diagram 01 has now been treated. Now I would be much less detailed with diagram 02. The main index is the same for diagram 01 and 02. Nice to see that some abbreviations have been done slightly differently, though.

Wire groups (diagram 02 only)

In addition to the Wire numbering ranges (diagrams 01 and 02) diagram 2 has these added wire groups. I am not certain about Schalttafel. I haven’t written switchboard, but maybe that’s correct? Also, main or mains here.

A Norm. Schalttafel im Führerstand I Standard control panel in the cabin I
B Norm. Schalttafel im Führerstand II Standard control panel in the cabin II
C Norm. Schalttafel für Wechselstrom Standard control panel for AC
D Norm. Schalttafel für Gleichstrom Standard control panel for DC
E Schalttafel für Relais Control panel for relays
H Klemmbrett am Hauptschalter Main switch distribution board
J Klemmbrett auf dem Transformer Transformer distribution board
K Klemmbrett im Vorbau I Distribution board in stem I
L Klemmbrett im Vorbau II Distribution board in stem II
M Klemmbrett für Oelbecherwärmer Distribution board for oil pan heater

Drawing 02-fig.3 – Fully annotated full installation diagram

Drawing 02-fig.3 – SBB Historic PL_105_00129_SchaltplanFuerMontage (full 212 * 61.5 cm). Annotated with transparent fields by Øyvind Teig. Signed in red (Press for more pixels 10MB)

Finally 02! Above I have annotated the diagram, just like in drawing 01-fig.8. You can compare the two diagrams in the Intro. I assume that the contents of this diagram causes it to be wide screen as compared to diagram 01. This one contains all the wiring info! Yo can see this especially on the left side of the diagram, the two motor layouts. In diagram 01 the wires are drawn directly to the speed switch, but on this diagram they go via an electrical conduit (trunking) tray of some sort. This is easily seen just above the motors. I have not seen these pictured anywhere, but I will look out for it.

Drawing 02 – Title and revisions blocks

Compare with Drawing 01-fig.3 – Title and revisions blocks for drawing 01.

You’d have to open the above figure to find these fields. Title to the right and revisions to the left.

Drawing 02 – Title block

Part of the heading is mit Nutzbremsung or with regenerative braking. Same point as for diagram 01. We see that this is order 133242 (a lower number than for diagram 01). Again, I don’t know what “Br7 Lok.” means. First drawn and signed on 14.X.25 (14Oct1925), some weeks after diagram 01. This is the diagram for the road numbers #14301-#14318 as 14301 – 14318, year 1924. Same as diagram 01.

Drawing 02 – Revisions block

There are two revisions. Korrekturen nach Angabe der Montage ausgeführt or Corrections carried out after specifying the assembly. With initials / signatures.

  • 11.III.26 (11Mar1926) G1. There are several G on the diagram. I don’t know what this means. H.A. are the initials. Same date and initials as diagram 01!
  • 9.IX.26. (9Aug1926). Initial B. Same date and initials as diagram 01!


I have not made excerpts of this diagram, as I did with diagram 01. It’s probably not needed since the electrical parts would be the same. I have not found any discrepancies between the diagrams. I guess that would be hard to find for an amateur anyhow.

A small comment. Light blue lines: rods and gears from speed wheel in cabins. However, they must have forgotten or selected not to draw the gear connecting the rod at [165] auxiliary roller for driving the tap changer, [158] motor for speed tap changer and [162] locking magnet with closing contact. I am not certain the role of the rod there, but it has been drawn in diagram 01, at least partially up into [165]. The gear is totally gone in diagram 02. I indicate this by a blue circle around 165.

The biggest motor is in Dresden

01-fig.Y- The motor of 2400 kW on locomotive E 50 #42 at Verkehrsmuseum Dresden (Dresden Transport Museum). Photo Øyvind Teig (2018) (Press for more pixels)

My second very much outside the theme. I have personally stood by this motor and felt its grandeur! I visited Verkehrsmuseum Dresden (Dresden Transport Museum) in August 2018 (aside-aside: where I presented this) and discovered this electric motor. Well, not really. I discovered this nice museum in its beautiful building. When inside I could not miss this huge motor. It is from the E 50 #42 loco from 1927, which  is no more, but this is claimed to have had the world’s most powerful electric motor for locomotives. And biggest in size. Its Stundenleistung hourly output was 2400 kW. This locomotive had one of them. It was mode by Linke-Hofmann-Werke AG, Breslau and the electrical by Bergmann-Elektrizitäts-Untern. AG, Berlin. It ran in East Germany as EP 242 on the Görlitz-Breslau route, stationed at Magdeburg (if I understood the poster correctly). The motor’s outer diameter is 3360 mm and it weighs 18.7t. The locomotive was scrapped in 1952, but the motor was saved and displayed at the Verkehrsmuseum in 1955. This museum is not very large, but I was so impressed that I had to go there several times over two days. I have not found any web reference to the locomotive, not even at the museum’s web page. I also have it as one of my blog’s header pictures. Plus a free picture here. Update: I did find a picture at Wikimedia Commons here.

SBB Historic on Wikipedia

SBB Historic - F 125 00001-230 - Ce 6 8 III 14315

There are a lot of free pictures on Wikimedia Commons (like the above) and Wikimedia (like this list:

The above picture of the SBB Ce 6/8 III #14315 is huge, with 8470 pixels max. The Commons page also shows where the original is stored, at the  SBB Archive. Interesting to learn that they also have scanned the photo frame. Then certainly no historical data is lost.  It closed my case of Fig.1 aside. Fan frames (above). But the revision date was unreadable, and there is no date in the Commons page. But SBB Archive says it’s from around 1960 and that the original negative is 11.5 * 16 cm and the frame is paper. But no revision date there. I assume they would have enough dates in a table to find that date. But then, we must all stop at some point. Which I didn’t do about the fan frames. I easily got stuck on that detail.

Other very relevant pictures could be:

  1. SBB Ce 6/8 II #12251 at here
  2. SBB Ce 6/8 III #14301 at here
  3. SBB Ae 3/6 II #10401 at here (mentioned above)


Lots of answers from [JC]:

  1. Who’s behind the two signatures? I can’t even read the letters. The revisions are signed by H.A and B. In theory it could be possible to search for the signatures here
  2. What kind of paper is in the original?
    [JC]: It is some sort of copy paper – the problem is that we do not have the original drawing. What I scanned is a copy of the original. Those copies were used in the main repair shop, working copies so to speak.
    So, maybe I have to rethink what a copy is (as also discussed above). Make two or several from scratch. Make them 100% equal. Use and wear one and store the other tidy for backup. Define the tidy as “original” and the working as a “copy”. Being so used to thinking about copying machines, this was rather difficult to see. Uhh, cognitive bias!
    [JC]: I asked around about the paper that might have been used, but we can’t tell for sure without having the originals. It is possible that the originals have been lost – that happens a lot. Maybe someone had made a copy and it looked fresher than the original, as you said, then it became the new «original». On the SBB Historic archive (here) you can see our storage rooms. As you can see, there are many drawers for plans, but it would be impossible to store such huge papers as unfolded. Also, as archivists we are faced with messy things every day. Often the plans and files and documents reach us in a state of disorder, and it is our job to try and make them less messy and store them so they do not get further damaged. We should not (and this is a common misconception) try to restore documents as a rule. If it is damaged, we only have to prevent it from getting worse. Often, the damage also tells a story. Sometimes, the messy state of the documents tells us something about the way people worked!
  3. Did they use ink and nibs?
  4. Could they erase and leave no trace?
    Even if drawing 1 has two revisions, I have not found any scalpel scraping marks. I don’t know how visible they would be, though
  5. What kind of tools and drawing table and equipment?
  6. Did they use a magnifier?
  7. In the SBB Archives & Collections, are these drawings stored as folded, or have they been unfolded “once and for all”? In case, when was this done?
    [JC]: These drawings are sadly stored as folded. They were tucked in a folder, which was again in a bigger folder (size around A1) with lots of unfolded plans. The plans from the main repair shops are a bit messy ! Generally speaking though, we try of course to store our archives as well as we can. Most plans are unfolded, but sometimes we keep them folded because unfolding or unrolling them would a) cause more damage and b) the plans are simply too big to keep unfolded – storage space is an issue.
  8. See Standardized nomenclature?
  9. [32] Heizhüpfer is it heating unit and does it contain oil or water? [JC] responds (21May2020) that “The Heizhüpfer ought to be more like a switch – Hüpfer is another word for Schütz, which is a sort of switch and I find it is translated as a contactor. But I can tell only from the language perspective”. And [32] is drawn as something inductive as a curl, plus something that looks like a capacitor but probably is some kind of contact controlled by [170]. I will call it heating accessory from no on
  10. [71] Oelwärmeplatte is it oil heating pan?
  11. [87] Blocking relay – is it equal to the SBB Ae 3/6 II? And what was the cause for it being present?
  12. [111] Battery voltage?
  13. [208] Innenlampe is it lamps in trafo-part of central box?
  14. Is the drawing paper used translucent? Ref Drawing 02-fig.2 – The locomotives compared
  15. If you have even more time and want to help out, just search for “(?)” first, then plain “?” and comment (below) or mail me! You will be credited!
  16. I have come in doubt about 16⅔ Hz or 16.7 Hz. Even if a 50 Hz / 3 = 16⅔ Hz and not 16.7 Hz. I am almost certain that it traditionally was 16⅔, but I have seen some literature say 16.7 Hz. Even some of those I have listed below. There may be something about synchronousity. See Wikipedia (here).
    UPDATE 2Jul2021: 16.7 Hz is correct after 1995 in most European countries (but not in, f.ex. Norway, where 16⅔ Hz is still used) (see Wikipedia’s 15 kV AC railway electrification).

The history of circuit diagrams

RADIO NEWS p.626: “The Construction of the 9 Tube Super-Hilodyne” by Fred A. Jewell (The Experimenter Publishing Company Inc, New York, Volume 9, No 6. December 1927)

Aside (begin)
I have for years been impressed by how advanced the printing technology has been. I assume this just reflects how naïve I am about the theme. Here is an example that I scanned from a 1927 magazine that I have. A friend gave it to me years ago, because he thought I would appreciate it. He was right! Thanks, Anders R!

It is from RADIO NEWS (Dec. 1927). There is a 1200 dpi scanning (7MB) here. I just love radio tube diagrams and mechanical drawings. Enjoy and download!

This magazine had 720 – 577 = 143 pages. It was No. 6 that year, which means 720 / 6 = 120 pages on the average. However, it’s strange with “No.6” as stated on the back and inside, when they also state that there are “12 numbers per year”, and also “monthly”. But the impressing 720 pages still stand. This was at a time when they were using hot metal typesetting and photostat, I believe. No computers.

The RADIO NEWS was edited by a certain Hugo Gernsback. When I look him up, he’s not just anyone. (See Wiki-refs (below) for the italics words above. Don’t do it if you don’t have an hour or two!)
Aside (end).

Tim Slavin in [1] set me on the first track of this history here:

The history of circuit diagrams involves people finding common ways to describe electronic components. In 1909, for example, the International Electrotechnical Commission (IEC) started work to develop a common set of terms and symbols to describe electronics. Symbols were created for measurements and graphic representations of electronic objects. Over time, electronic symbols have evolved to represent use in different countries as well as different time periods.


I do try to look forward. By, like – learning XC and FPGA. And working with students, after I retired from the electronics industry. But I also love to look back. In my life it feels like there is more of it in that direction. Maybe I still have a Model to fulfil.


[JC] is Jin Chei of SBB Historic, in several emails. See My Krokis notes.


Numbered refs

  1. Circuit Diagrams by Tim Slavin, in beanz. The Magazine for Kids, Code and Computer Science (March 2014), see
  2. LOKI-Spezial Nr. 23. Faszination Ae 3/6 II“, magazin by Franz Eberhard and Hansueli Gonzenbach (around 2013). More at note 046:[18]. This magazine contains some excellent hand drawn vereinfachtes Schema, simplified diagrams:
    Hochspannungs- und Triebmotorstromkreis, high voltage and engine/motor circuit (p.29. Eberhard 1963)
    Steuerstromkreise für Hauptschalter, control circuits for main switches (p.30, Eberhard 1963)
    Stufenschalter Ae 3/6 II, speed step tap changer for Ae 3/6 II (p.33, Eberhard 1964)
    Hilfbetriebsstromkreis, auxiliary circuit (p.36, SBB 1963)
    Luftleitungsschema, pneumatics diagram (p.39, SBB 1925)
    Abtrennen des Fahrmotors, connection of drive motors (p.43, Eberhard)
  3. SBB Stangenlokomotiven Be 4/6 + Ae 3/6 II by Heinz Sigrist. (2016). More at note 046:[22]
  4. Induction traction motors and their control, chapter 6 in Electric Traction – Motive Power and Energy Supply: Basics and Practical Experience by Prof. Dr.-Ing. Andreas Steimel. (2008)
  5. Elektricitet og magnetisme (Electricity and magnetism, in Norwegian) by Peder Lobben, Kristiania (Oslo), 1908, H. Aschehough & Co. (W. Nygaard). 150 figures, 556 pages
  6. Elektriske vexelstrømme (Electrical alternating currents, in Norwegian) by Peder Lobben, Kristiania (Oslo), 1915, H. Aschehough & Co. (W. Nygaard). 168 figures, 450 pages
  7. Gotthardbahn/Ferrovia del Gottardo: SBB Historic Krokodil Ce 6/8 II 14253 in Trouble! by TrainspotterTV, as Bahnland Schweiz. Gotthardbahn Mai 2014: Krokodil 14253 in Troubles, see This is exciting tranquility! Allow yourself to enjoy the whole 12:42 long movie! The icon here shows the first ⚡ spark at 7:08. The second ⚡ spark is at 7:35. Watch when they are crossing the bridge back to Erstfeld station.. I won’t say when
  8. – Herzlich Willkommen bei Bruno Lämmli, see and (terminology) (Thanks [JC] for this link)
  9. Elektrolok i Norge (Electrical locos in Norway) by Nils Carl Aspenberg, on Baneforlaget, 2001. In Norwegian. This book also has a rather extensive review of the technicalities of electrical locos, plus how these have developed over the years. See 229:[14]
  10. Locomotive Ce 6/8 II “Crocodile” by Hans E. Wettstein (SBB Historic publication 2022) also has some nice circuit diagrams. See 201:[36]
  11. Versuchsfahrten einer Wechselstromlokomotive mit elektrischer Nutzbremsung by Hans Behn-Eschenburg (1919). Read at the ETHZ (Eidgenössische Technische Hochschule Zürich) library at PDF is here. This is ref 3. in the above mentioned 201:[36]

To the top


Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.