Class E 04

Updated: August 2026 – A boxy locomotive body, a visible chassis frame, carrying axles front and rear: the Class E 04 dates from a time when electric locomotives still looked like steam engines without a boiler. This page explains what’s behind the designation, how you recognise the class, and why the same vehicle turns up under three different numbers in different sources.

What is Class E 04?

The E 04 is an electric locomotive from the 1930s, built by AEG in 23 examples for the 15 kV AC network. Its wheel arrangement is 1’Co1’: three driving axles coupled together, with one carrying axle each in front and behind. It belongs to the group of so-called standard electrics, with which an attempt was made for the first time to build German electric locomotives to shared design principles rather than developing them afresh for every route.

Later, the class received new numbers: at the Deutsche Bundesbahn it became Class 104, at the Deutsche Reichsbahn Class 204. This double numbering is typical of German vehicles of this era and one of the most common stumbling blocks in research.

How to recognise a classic electric

Electrics from the 1930s differ fundamentally in several respects from modern vehicles such as the Class 101. The features are clear enough that you can spot them even without prior knowledge.

The general sequence for identifying classes – first the body shape, then the wheel arrangement, then the number – is described in the guide to identifying classes.

Placing it: small series, clear tasks

If you’re used to today’s production numbers, 23 machines seems remarkable. Back then it was normal: the electrified network was small, and locomotives were procured for individual groups of routes. The following table shows how electric locomotive design changed over the decades.

Feature	Classic electric like the E 04	Post-war electric	Modern three-phase locomotive
Carrying axles	present	mostly absent	not present
Running gear	frame construction with coupled axles	bogies	bogies with individual-axle drive
Typical quantity	double figures	triple figures	triple figures, distributed across Europe
Drive	individual-axle and rod drives	Tatzlager and spring drives	three-phase drive with converter
Current status	museum	partly museum, partly special services	regular service

How strongly the designs differ is shown by a direct comparison with the Class 110 (E10) from the post-war era – there, carrying axles and visible drive components have already vanished.

Photographing in a museum setting

You’ll photograph an E 04 standing still almost every time – in a hall, on an exhibition track, or at a museum event. In collections such as the DB Museum Koblenz, classic electrics are on permanent display. That places different demands on you than trackside photography.

The guide to a photo archive for spotters describes how to keep such shots usable in the long term. A structured sighting log is worthwhile for recording alongside it.

What the designation E 04 tells you

Old electric-locomotive designations look arbitrary, but they follow an order. The leading E simply means electric locomotive and separated these vehicles from steam and internal-combustion traction. The number after it wasn’t a running count but was roughly grouped by purpose and design: low numbers marked express and passenger locomotives, high numbers freight locomotives. The two-digit serial number after that counted the individual machines of a class.

This system held until the switch to pure digit designations. At the Deutsche Bundesbahn, the E became a leading one: E 04 became 104, E 16 became 116, E 17 became 117, E 18 became 118. At the Deutsche Reichsbahn of the GDR it worked differently – electric locomotives there got a leading two: E 04 became 204, E 18 became 218. Both railways counted independently of each other, and that’s exactly where today’s misunderstandings in sources and databases come from.

In practice, that means two things. First: a three-digit number alone doesn’t reliably tell you which vehicle is meant – you need to know which system it comes from. Second: one and the same vehicle can appear under three designations in different sources without anything having technically changed.

Things only become reliable with today’s twelve-digit vehicle number to the European standard. It contains a country code, vehicle type, running number and a check digit, and is recorded in the register even for museum vehicles. Anyone documenting historic sightings should therefore always photograph the full markings and not just note the short running number – it saves a lot of guesswork later.

Common mix-ups

The four-axle relatives are found under Class E 17 and Class E 18.

Conclusion

The E 04 isn’t a vehicle for everyday platform spotting, but a piece of engineering history. Its value for spotters lies in the fact that it shows the difference between old and new electric-locomotive design in a single image: carrying axles, a visible frame, coupled driving axles. Anyone who has seen that once will place other classic electrics faster too.