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 design..

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 95.

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 further.

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 ft).

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.

Mechanical Systems

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.

Electrical Systems

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 engine’s roof.

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 period.

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 repaired)

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 1980.

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 machine.

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.

Sources

"World Electric Locomotives," by Ken Harris, Jane’s, New York, NY, 1981, 160 pages. ISBN 0 531 03728 2.
"The Great Book of Trains"; Brian Hollingsworth and Arthur Cook, Portland House, New York, NY, ISBN 0-517-645515-7, 1987.
"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 ]