In the first mainline electrics of Europe, one giant electric engine drove a so-called "blind axle", which in turn drove the locomotive wheels with coupling rods, just like on a steam locomotive. But soon designers realised that it is much easier to build multiple drive units (i.e. wheels driven by the same engine, or at least wheels in the same frame) into an electric locomotive than a steamer.

This came handy in the design of heavy mountain locomotives. The latter faced two opposing requirements: they had to take curves easily, and had to have as many driven wheels as possible.

One solution is: take a locomotive with two drive units, add more wheels to those, and put extra machinery boxes atop the protruding ends in front of the drivers' cabins, and these protrusions can be articulated. And thus the crocodile was born.

The pioneers from Switzerland

The drive units of the first crocodiles still had blind axles. I'll show two.

The first, made for the state railway SBB to run trains across the Gotthard pass (electrified in response to the coal shortages during WWI), actually had two variants (class Ce 6/8 II¹: 1655 kW/2120 HP², 1919–1922, from 1941 rebuilt into 2688 kW/3605 HP class Be 6/8 II; class Ce 6/8 III: stronger at 1809 kW/2426 HP, also fitted with different coupling rods, 1925–1926, later re-classified Be 6/8 III).

Preserved unit SBB Ce 6/8 II [no.] 14253 (in original livery) with special train at the lower part of the Wassen double loop. From RailFanEurope

Between 1923–1927, SBB crocodiles of both variants were also delivered to Austria as class 1100.0 and 1100.1 (later ÖBB class 1089/1189), but with a different (lower) nose design.

Preserved unit ÖBB 1189.02, here with old numberplate as 1100.102 (an example of the second version of the SBB crocodile) at Semmering station. Photo by Christian Beckers from RailFanEurope

Rhätische Bahn (RhB), which runs a large narrow-gauge (1 m) network and is kind of the state railway of Graubünden canton, built its Ge 6/6 I crocodiles 1921–1929 already without the non-driving front/end wheels (which steam locos need for stable running at higher speeds, i.e. staying in the tracks). Their one-hour power rating of 940 kW/1261 HP was significant for a small narrow-gauge loco.

Preserved unit RhB Ge 6/6 I [no.] 414 with nostalgic train near Bonaduz. From Markus' Steam Pages

Made In Germany

On steep mountain mainlines, the normal locomotive of longer trains wasn't enough – so-called pusher locomotives were called for help, locomotives that pulled up from behind in the valley station, and without being coupled to the train, helped pushing up the slope. The first German crocodile was made exclusively for this purpose: the eighteen members of class E93 (later West German 193), built 1933–1939. They already had one motor per axle, and had a one-hour power rating of 2501 kW/3303 HP.

DB 193 [no.] 007 in unusual line service with freight train in Heidelberg, 1977. Photo by Roland Linke from IG Deutsches Krokodil

The most famous crocodile was a stronger (3240 kW/4345 HP), longer, faster version developed from the E93: the heavy freight locomotive E94. A solid construction: first built in 1940, last (200th) in 1954 in West Germany (where it was later class 194). The updated design of the last batch (later subclass 194.5) already foreshadowed post-war locomotive designs, and was even stronger (4680 kW/6276 HP).

The locos that ended up in East Germany (later East German class 254) were subject to an odyssey: they were carted off by the Soviet Union as reparation for WWII, only they weren't really fit for the Russian broad-gauge network – so they stood around for a few years before being returned.

A third break-up product of the Nazi Reich, Austria, also kept a number of the machines – they became class 1020 there, and survived into the late nineties in regular service.

Two ÖBB 1020 crocodiles (and a 1044.1) disappear into a tunnel in the big horseshoe curve at Matrei on the Brenner line. Photo by Manfred Weinhandl from Bahnbilder.de

The crocodile nose was dropped in later designs as unnecessary and uneconomic – by then mainlines had enough clearance for longer single-box locomotive bodies in curves. But I note there was one big advantage of the crocodiles over modern units: their 'snout' could act as a 'crash zone' during collisions, protecting the locomotive driver.

1. The old Swiss numbering system: 6/8 stands for 6 driven axles out of 8; the lower-case e stands for electric, the upper-case letters correspond to power classes (for locomotives in increasing order: G-E-D-C-B-A-R); the Latin number is to differentiate different types that fall into the same categories in the previous four, and is assigned chronologically.↑
2. HP is the English horsepower (c. 0.7457 kW) for our American readers; not to be confused with German Pferdestärke (c 0.7355 kW). All power ratings in the diary are one-hour ratings (maximum sustained power is usually about 10% lower).↑

Previous Monday Train Bloggings:

1. (Premiere/ modern Austrian trains & locos)
2. Adventure
3. Fast Steam
4. Heavy Haul
5. Forgotten Colorado
6. The Hardest Job
7. Blowback
8. Highest Speed
9. New England Autumn
10. Trainwreck
11. Bigger Than Big Boy
12. Tunnels
13. Failed Designs
14. Demarcations
15. Crazed Designs
16. Trains In The Arts
17. Railway Cathedrals
18. Design Dictators
19. Slippery Slope
20. Alta Velocità
21. Winter In Bulgaria
22. Nice Station
23. Field Railways