Germany’s Heavy Duty E93 Freight Locomotive
Author: Kurt H. Miska, ETE 801
Sometimes called the German Alligator, the E 93
(and E 94/BR 194) electric, heavy freight locomotive represented a
significant technical achievement when it joined the Deutsche
Reichsbahn (DR) in 1933, but before delving into this machine, I have
to set the stage that led to this successful and groundbreaking
Setting the stage
In the early 1930s, the DR had operated two
electric engines for heavy freight operations, the E 91 (specifically
the E 91.9) and the E 95 but both of these machines were designed and
built in the mid-1920s and some thought had to be given to a
replacement. The DR owned 46 of the E 91.9 and only six of the giant E
The E 91.9 was a freight locomotive intended for
steep grades and mountainous regions and was not a particularly fast
machine. The E 95 was designed primarily for more level regions. Klaus
Bochmann (see Sources) writes, "By default, one can say that the
E 95 was the only true predecessor to the E 93. The reason for
development of the E 95 was the planned electrified route Breslau -
Liegnitz - Arnsdorf, part of the long, level Oppeln - Kohlfurt - Görlitz
line. But, the former line was not built and, as a result, the DR had
to find other uses for the E 95. These locomotives wound up on the
Dittersbach - Lauban - Görlitz line where they served well, perhaps
even exceeded expectations." Though developed and built for
non-mountainous service, the E 95 acquitted itself favorably on some
rather severe grades. It had excellent acceleration for passenger
service but despite its modest top speed of 70 km/h (44 mph), it
covered an impressive 7,000 km (4,340 miles) per month.
The worldwide economic crisis of 1929 had severe
consequences on the DR , slowing if not altogether stopping
electrification of many rail lines. Still, by 1930 the DR initiated
the electrification of the important Stuttgart - Ulm line for two
reasons - one being the sheer necessity of this step and two as a
means of combating some of the massive unemployment that prevailed.
Service on the newly completed electrified line began on July 1, 1933.
This line features what is probably the most famous steep grade in
Germany, the Geislinger Steige. This stretch is so steep that to this
day, helper service (pusher Lok) is necessary to move a heavy freight
train up that grade. Once electrification was completed, the need for
a pusher engine quickly became apparent and existing E 91s were called
in from Munich. While a newer engine would have been desirable,
economic reality dictated otherwise. Still some thought had to be
given to a replacement because the side rod drive system was outmoded
since nose-and-axle suspended motor drive was already well proven.
Also, the DR had done some calculations figuring and learned that
maintaining a rod-driven engine of C’C’ axle arrangement was more
costly than maintaining a Co’Co’ engine. The die was cast. Plans
for a replacement moved forward. But, the stage needs to be set
The three prototypes of the E 44 electric
locomotive had also arrived for evaluation by the DR. This engine
broke ground in that it featured two four-wheel bogies with
nose-and-axle suspended motor drives. Tests quickly proved the
soundness of the design. In fact, the test were so successful that the
E 44 was ordered in quantity for medium-duty service. Further
endorsement of the design concept was that the new heavy freight
locomotive, the future E 93, would also use this technology.
Finally, the E 95 definitely did not serve as the
basis for the E 93 because the former was a very expensive and complex
double or two-unit-locomotive. It could be uncoupled into two halves
for regular service and maintenance. All of the electrical and much of
the mechanical equipment was duplicated. All in all, an unsatisfactory
approach for the future E 93.
Design of the E 93
Construction of the new heavy freight locomotive
was undertaken by AEG (Allgemeine Elektrizitäts Gesellschaft). The
German economy, like the rest of the world, continued to reel from the
disaster of 1929 and thus the DR did not feel the need for more than
two of the new locomotive. In fact, the engines were not even
considered to be prototypes but rather production machines. Numbered E
93 01 and E 93 02, they were, in reality, lengthened E 44s featuring
two three-axle bogies connected with what might best be called a
bridge structure. The result was a locomotive that was a variation on
the Swiss/Austrian Crocodile theme. The middle structure, bridging the
two three-axle bogies of the locomotive, contained the necessary high
voltage transformer and related electrical and mechanical equipment.
One disadvantage of this construction was the relatively high weight
of the bridging structure and one partial solution to the problem was
to have the center section house only that equipment absolutely vital
to the engine’s operation. Other equipment, such as the batteries
and air compressors were installed in the housings over the bogies.
Staying within what certainly must have been very
specified, yet not mentioned by Klaus Bochmann, weight limits greatly
concerned the design staff at AEG. There were some reservation as to
whether or not the new engine could be built to a Co’Co axle
arrangement while staying within the 20 ton axle loading. The entire
center section was a welded structure with the sheet metal being
attached with rivets. The bogies were a traditional riveted structure,
rather than being welded since some concern had been expressed about
the latter. This is especially curious since the E 44 engine’s
welded bogies had proven entirely reliable. The overall length (LüP)
of the E 93 was 17,700 mm (58 ft) and the wheelbase was 12,800 mm (42
The electrical system was also new and had been
simultaneously installed in the E 04 and E 44 electric locomotives.
One of the features of the newly developed system enabled much finer
speed control of the engine, much like a vernier dial.
Over a period of six years, 18 of the E 93 were
delivered by AEG to the Reichsbahn. All in all, the new engine
performed extremely well. Wheel wear was not nearly as severe as
initially predicted. The first four of the series (E 93 01 to 04) was
limited to 65 km/h and rest, starting with E 93 05, were permitted to
run at up to 70 km/h (44 mph). The reason for the 65 km/h (40 mph)
limit of the first four engines was that they were specifically
assigned as helpers on the Geislinger Steige.
Test and Evaluation
While designing the E 93, the following
requirements had to be considered.
- 600 ton trains on a 10% grade at 50 km/h (31 mph).
- 720 ton trains on a 22.5% grade at 40 km/h (25 mph).
Calculations showed that with the above loads a
tractive effort of 36,000 kg (79,200 lb) would be required to set the
train into motion. To that end, six motors (type EKB 620) delivering
385 kW (516 hp) for a total of 2,310 kW (3,100 hp) at 70% of top
speed, or 45.5 km/h (28 mph) for the first four E 93s and with the
transformer supplying 1,680 kVA. These requirements were specifically
for the Stuttgart - Ulm line. During initial service of the E 93 that
meant trains of 1,600 tons to Göppingen and then 1,200 tons to
Altenstadt near Geislingen.
Modelers of German model railroads often wonder why
a symmetrical locomotive, such as E 93, are marked with the numbers 1
and 2 or the letters V and H at the driver’s position. Well, there
is indeed a front (V or 1 means vorne) and rear (H or 2 means hinten)
and this is dictated by the suspension (springing) of the engine.
Further, there is a left and right side. Left and right are determined
by the direction of travel. In right hand traffic, such as in Germany,
the passage way in the center section is on then on the left side.
The front and rear sections are coupled to the
center section so that push and pull forces are distributed uniformly.
The hinging or coupling to the front and rear sections is by means of
large pivot pins or trunnions. The entire structure makes for a simple
yet rugged and reliable framework.
The two three-axle power bogies of the locomotive
are very similar in their construction. The frames of these units
consist of 28 mm (1.10 in.) steel plate that is riveted together.
There are four crossmembers to further strengthen this large,
rectangular box structure. The first of these crossmembers also
secures the buffers, couplers other parts. Starting at the front, the
axles are numbered 1, 2 and 3 and the second set follows with 4, 5 and
6 with number 6 being the outermost.
The second crossmember is located just before the
second axle. This crossmember is used to anchor the quill of the
nose-and-axle-suspended motor of the first axle. Along the top flange
of the second crossmember the pivot pin is also located.
To avoid excessive stresses on the center section
of the engine, it was coupled to both bogies using ouplings similar to
those used in coupling a steam locomotive to its tender.
The coupling absorbs pulling stresses and a pair of
sprung buffers does the same when the engine is used in pusher
service. The buffers also act to straighten the engine after
negotiating a turn and thus also reduce wear on the wheel flanges.
From the outset, the six axles were installed with,
for all practical purposes, zero sideplay; however, this led to some
wheel flange wear on the center axles of each bogie. The middle axles
of each bogie used wheels with 10 mm (0.40 in.) thinner flanges and to
further alleviate this problem, the DB installed flange lubrication
systems in the 1950s. Conventional leaf spring suspension was used.
The locomotive’s center section, housing the main
transformer and the two engineer’s stations, rests on the bogies on
three-point mounts. The main load was transferred to the four large
dashpots on each corner of the center section. Each bogie features two
of the dashpots, one on the left and one on the right.
The center section is also a welded frame covered
with riveted in place sheet metal. Large sections of the sheet metal
can be removed quickly to ease servicing and maintenance. Once inside,
the visitor will find a passage way on the right. The main transformer
is in the center. Cooling air enters through four large louvers on
each side and is directed to the transformer. The engine driver’s
positions are much the same as those found on the concurrent E 44.
Compressed air needed for braking is furnished by an
electrically-driven Knorr pump that furnishes air to two master brake
cylinders. Two brake shoes per wheel are used. For additional
traction, more specifically, when dealing with the Geislinger Steige,
sandboxes are installed that supply sand to every wheel. However,
starting in 1957, as the Indusi system was being implemented, some of
the sandboxes had to be removed to make room for this now widely used
safety system. With reference to the Geislinger Steige, it should be
noted that E 93s assigned to pusher service featured special couplers
that could be released without having to stop.
Starting on the top of the E93, there are two type
SBS10 pneumatically-operated pantographs which are connected by large
bus bars to the main circuit breaker, an oil-filled unit which can
handle up to 100 MVA. In addition, each pantograph has a separate
switch so that they can be individually disconnected in case of a
problem. Power (15,000 volts at 16 2/3 Hz) is fed to the oil-cooled
main transformer delivering 1,680 kVA continuously. The secondary has
18 taps corresponding to 15 taps for the 15 speed ranges of the
locomotive and three for auxiliary functions, such as train heating,
an indication that freight was not the E 93’s only calling in life.
The pneumatically-operated tap changer provides operating voltage
ranging from 58 to 551 volts. In addition, there is a cam-operated tap
changer for fine adjustment of the engine’s speed. The E 93 is
powered by six Type EKB 620 electric motors of 650kW (870 hp) each.
These are 10-pole series-wound nose-and-axle-suspended motors
connected in parallel. Forced air cooling is used. Their power is
transmitted via a reduction gearbox. With minor changes, the motors
are the same as those found in the E 95 locomotive and having shown
excellent reliability and ease of maintainability. The louvers on the
side of the engine serve to conduct cooling air to the electrical
components. A bank of 12 braking resistors is mounted on top of the
Service Before and After the War
Built primarily for heavy freight service on the
Kornwestheim (Stuttgart) - Geislingen - Ulm, the first E 93,
specifically E 93 01, was put into service in the summer of 1933 at
the Kornwestheim service facility with E 93 02 following that
November. Two more engines followed in 1935 and nine more in 1937.
When E 93 07 and E 93 08 were completed, they were assigned to Bw Ulm,
where the latter remained until 1951. One of the E 93’s major duties
was pusher service up the Geislinger Steige.
In 1938, the E 93 also saw service hauling heavy
ore cars on the Rosenheim - Salzburg - Linz line to a large iron ore
processing plant in Linz. By 1939, when the successor E 94 was taking
shape, AEG delivered the last of the E 93s, E 93 14 to E 93 18, and
after initial service in the Halle region of middle-Germany, they were
turned over to southern service facilities during the 1940 to 1942
The E 93s under the direction of BRD Stuttgart were
dispersed as follows:
Bw Kornwestheim - E 93 11, 16, 17, and 18
Bw Geislingen - E 93 01 - 04
Bw Ulm - E 93 05 - 15
Despite all the chaos of the last days of the war,
electric service between Stuttgart and Ulm was maintained, even if it
was with interruptions. There were stretches were the catenary was
completely missing and the enterprising engineers went through those
section using sheer momentum.
Came the end of World War 2, only seven of the E
93s survived, these being E 93 03, 13, 14, 15 and 16. Two engine, E 93
01 and 18, needed major maintenance and were therefore not immediately
serviceable. E 93 06 and 12 were damaged so severely that they were
deleted from the inventory and parted out at Betriebswerk (Bw) Ulm. By
the end of 1951, thirteen of these locomotives were back in
Kornwestheim and E 93 01 to 93 05 were stationed in Geislingen. .
The other eight war damaged E 93s as well as the
two due for periodic maintenance were rebuilt at Ausbessrungswerk (AW)
Esslingen. The less damaged Loks E 93 07, 08, 09 and 11, as well as E
93 01, were repaired quickly and returned to service in late 1945.
Engines E 93 05, 10, 17 and 18 followed in April 1946 but E 93 02 took
longer and wasn’t ready until March 1947. In the 1949/50 period, the
E 93s were allocated as follows:
Bw Kornwestheim - E 93 18
Bw Geislingen - E 93 01 to 04
Bw Ulm - E 93 05, 06z, 07 - 11, 12z, 13 - 17.
(Note: the letter z denoted "von der
Ausbesserung Zurückgestellt" or temporarly not to be
In March 1951 all the Loks stationed in Ulm were
reallocated to Kornwestheim because the former received E 94s. The E
93s were needed for the newly electrified line Ludwigsburg -
Bietigheim - Mühlacker. Further, by 1955 electrification had reached
Heidelberg. The E 93s were constantly on the move and had to continue
to do so at least until 1957 when the Deutsche Bundesbahn started to
take delivery of the new E 50.
By 1958 the Geislingen E 93s were transferred to Bw
Kornwestheim but E 93s 01 - 04 remained in pusher service up the
famous, or is it infamous, Steige. However, change was on the way.
During the second half of the ‘50s some E 94s entered Steige pusher
service at Geislingen. With increasing electrification into the Baden-Württemberg,
the E 93 (and some E 94) were badly needed while the DB waited for
delivery of more E 50s.
About 1968, the 18 E 93s were redesignated as BR
193. These hard-working, reliable Loks were spread quite thin and it
was a increasingly rare sight to see one on the original Kornwestheim
- Ulm line.
The last BR 193 to pass through the AW München was
BR 193 006 on September 16, 1976. It was a sign that the end neared.
Exactly one week later, on September 23, 1976 saw the retirement of BR
193 010. BRs 193 001, 005, 007, 009, 015 and 017 were next. In
November 1980, BR 193 011 followed. With exception of BR 193 007,
which survived as a museum engine, the rest were dismantled at AW München.
Interestingly, BR 193 007 was the only one of its type to ever venture
outside of Germany’s borders. This Lok took part in the two-year
Crocodile Exhibit in the Lucerne Transportation Museum from 1978 to
The decline of the BR 193 continued rapidly in 1980
and speeded up even more. Even in Geislingen service the BR 193 was
used less and less frequently. Daily use had been about 250 km (155
miles) during 1970s but this declined to about 177 km (110 miles)
daily in 1979. After 1980, ten BR 193s remained but BR 193 002, 003
and 018 were retired by 1983. The last locomotive to be retired was BR
193 004 on September 17, 1984.
Some impressive distances were covered by some BR
193s. For example E 93 001 covered about 2.5 million km (1.55 million
miles) but this was mainly in pusher service. E 93 11 made it to 4
million km (2.5 million miles). The average for the type was from 3.5
to 4.0 million km (2.2 to 2.5 million miles). Yes, the E 93/BR193 was
one impressive, useful and reliable machine. In German we might say
that the E 93 was "ein wuchtiger Brocken" or one impressive
Author’s note - This article is largely based
largely on information contained in "Die Baureihen E93 und
E94" by Klaus Bochmann, Eisenbahn Journal, I/90. Translation is
not verbatim but the author accepts responsibility for its accuracy.
"World Electric Locomotives," by Ken
Harris, Jane’s, New York, NY, 1981, 160 pages. ISBN 0 531 03728
"The Great Book of Trains"; Brian
Hollingsworth and Arthur Cook, Portland House, New York, NY, ISBN
"Die Baureihen E93 und E94" by Klaus
Bochmann, Eisenbahn Journal, I/90, ISSN 0720-051 X..
"Das Grosse Typenbuch Deutscher
Lokomotiven," Weisbrod, Bäzold, Obermeyer, Trans Press1995,
336 pages, ISBN 3 344 70751 5.
"Die E94 - Biographie einer
Erfolgskonstruktion", Märklin Magazin, 6/88, p. 36.
Editor’s note - Appart from the sources
mentioned by Kurt H. Miska, there are at least two other books, that
cover the E93 in detail
"E93, Portrait einer deutschen Güterzuglok"
by Andreas Braun and Florian Hofmeister, Verlag Florian Hofmeister,
Bayrisches Eisenbahnmuseum e.V., Munich, 1986, ISBN 3-88563017-6.
"Baureihe E93" by Thomas Estler,
Trans Press2000, 127 pages, ISBN 3 613 71122 2.
[ last updated 31st Dec 2003 ]