An Interesting Heavy Electric Freight Locomotive - The KPEV EG 5 and DRG E 91³  

by Jim Fischer

This Elok is not going to win any beauty contests but it is representative of what Eloks looked like in the early 20th century. Photo courtesy Jim Fischer.

If you can imagine two huge, mobile transformers racing toward each other on the same track and stopping just short of demolishing a wooden box car, you have, at least, a partial picture of the appearance of the German Type E 91³ electric locomotive from the 1910s.

    This then is a story about an old, less than elegant, electric freight locomotive built for the Royal Prussian State Railways (Königliche Preußische Eisenbahn Verwaltung - KPEV) in 1915 and later by the German State Railways (Deutsche Reichsbahn Gesellschaft - DRG). This locomotive was designed primarily to haul heavy freight at tolerable timetable speeds.

   The E 91³ is not to be confused with the well-known multi-bodied, twin drive E 91 and E 91⁹ “crocodile style” locomotives that saw many decades’ service both with the KPEV and K. Bay. St.B (Königliche Bayerische Staats Bahn), later with the DRG and eventually with the DB and the East German DR. The latter locomotives saw extensive service and were highly successful, and some locomotives from the E91⁹ series were even split apart and built into successful yard switchers (BR E 61, BR 161).

   The E 91³ was a shaft coupled, outside-framed locomotive sharing three separate bodies and trucks, each drive frame supporting a superstructure. The permanently coupled units resulted in a B+B+B configuration. This locomotive, looking like the product of a runaway boxcar that crashed into an electrical supply house was clearly designed to haul freight. It may never have hauled a passenger train except in mixed service; if it did, the waiting passengers must have looked the other way as the locomotive approached the station. That being said, some viewers may choose to view it as a rather rugged example of practicality and function. Inasmuch as its appearance neither draws up images of beauty nor blinding speed, what it lacks in these areas it gains in a simple display of utility and purpose.

    In 1912 the KPEV began a program to build approximately 20 locomotives for goods traffic in the mountains of Silesia (Schlesien). MSW (Maffei-Schwartzkopff Werke, Wildau) and SSW (Siemens-Schuckert Werke, Berlin-Erlangen). The order from MSW was withdrawn, leaving only twelve locomotives from SSW. Linke-Hoffmann built the running gear and other mechanical systems. The locomotives were initially assigned to handle 1,200 ton trains operating on a grade of nearly 0.6% (6⁰/₀₀) and 500 tons at a grade of 2% (20⁰/₀₀) at a speed of 12.4 – 25 mph (20 - 40 km/h). At these recommended axle loads, these locomotives proved to be powerful. Though provided data gave no ratings, comparisons to contemporary locomotives in literature on the subject would suggest this locomotive developed from 1,200 to 1,600 hp, a good figure for the time. (One source gives 2,040 hp)

    The first locomotive of the KPEV class EG 5 series was numbered EG 538 and was placed in service in 1915 on the local electrified lines from Nieder-Salzbrunn to Halberstadt, and later in 1916 on its intended primary service line from Königszelt through Dittersbach to Felhammer. This line was electrified at about this time, so the EG 538 must have been expressly built for this area. Due to the effects of World War 1, the last locomotive of the series was not placed in service until 1922, number EG 549. These machines were renumbered by the DRG in 1927 to E 91 38 through E91 49.

    The E 91³ belonged to a group the German experts like to call the “Gepäckwagen Lokomotiven” or “baggage car locomotives.” The wooden middle cabin looks as if it is more like the typical “Zugbegleiterwagen” or guard van (caboose) assigned to freights. Designed for the grades of the Silesian mountains, this three section locomotive was designed with the cab in the center section with a baggage compartment. Two identical, interchangeable sections housed the transformer and related gear. The end frames gave the impression of huge transformer boxes one would find in a stationary power substation. Of interest is that these transformer boxes were galvanized and the center section built of wood. (Galvanizing is the process where sheet steel is coated with zinc to retard corrosion.)

    Each frameset was driven by a single motor connected to a blind axle counterweighted shaft drive, a typical design before the first World War. This locomotive used what is best described at “outside frame construction.” What this means is that the wheels are located inside the box of the frame which extends beyond the gauge. The wheel bearings were mounted on the outside of the wheels on an axle extension. The drive rods connecting the axles were on the outboard side of the frame, typical of narrow gauge steam locomotives and small switchers of the era. An eccentric rod drove a mechanical air pump on the left side of the two end units. The twin control center cab, with its characteristic freight compartment with sliding side doors, was built to overhang the ends of the middle frame. By its design the three truck B+B+B suffered from poor running characteristics, since each of the close-coupled framesets was independent. The effect of the running gear counterweight action exacerbated the problem at high speed. Later the drivers were re-set with better spring suspension allowing an improved top speed from 28 – 31 mph (45 - 50 km/h).

    The three propulsion motors were permanently connected in series and connected to the secondary winding of the oil-cooled transformer. Power to the motors was fed through one magnetic contactor and the output was then split into three parts for use by the motors. The locomotive driver used a 15-step manual controller to operate the engine.

    Service of the E 91³ was, although demonstrative of the high tractive effort of electric traction, not particularly marked with success, due mainly to the rough running characteristic. Nonetheless, they were in service from between 12 to 20 years. In November 1934, E 91 46 and 47 were taken out of service. Eventually in September 1936, E 91 39, 42 - 44, as well as 49 also saw their end in assignments. In the 1930s, two locomotives, E 91 38 and 45, were rebuilt by the DRG as stationary transformer heater units to heat standing passenger trains in winter. They were stationed at Hirschberg and Halle/Saale, respectively. In November 1942, the remaining locomotives E 91 41 and 48 were scrapped, probably for the war effort. In September 1943, E 91 40 was the last of the E 91³’s to be retired.

Characteristics of the E 91³ Electric Freight Locomotive

Sources

Joachim, Ernst, Elektrische Locomotiven, DRG/DB/DR, 1973, Alba Verlag, Düsseldorf, Germany, ISBN 3-8794-015-8.

Weisbrod, Bäzold, Obermeyer, Das grosse Typenbuch deutscher Lokomotiven,1995, Transpress, Berlin, ISBN 3-334-70751-5.

Editor’s note – this translation appeared in Der Eilzug, newsletter of the ETE Sacramento Chapter, Vol. 2, Issue 8, September 2001. Editing and additional material provided by Kurt H. Miska.

Note: This article appeared originally in the ETE EXPRESS, No. 97, page 12.