ELECTRIC LOCOMOTIVES OF THE EU06 AND EU07 SERIES IDENTICAL OR DIFFERENT?

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ELECTRIC LOCOMOTIVES OF THE EU06 AND EU07 SERIES
IDENTICAL OR DIFFERENT?

https://www.robo.eu.com/blog-2/stare-tory/lokomotywy-elektryczne-serii-eu06-i-eu07

ELECTRIC LOCOMOTIVES OF THE EU06 AND EU07 SERIES

             In December 1961, PKP carried out technical acceptance of the first Bo'Bo' locomotive (axle system) of the EU06 series at the English Vulcan Foundry factory in Newton le Willows. The newest electric locomotive for PKP at that time was built in the oldest locomotive factory in the world. The Vulcan Foundry was founded in 1825 by Robert Stephenson, son of George Stephenson, the famous inventor of the steam locomotive.

             In 1961-62, English Electric built 20 four-axle, universal electric locomotives of the EU06 series (pop. "Englishman") for PKP. The rated continuous power of this locomotive was 2000 kW, and the hourly power was 2080 kW. The electric locomotive could drive passenger trains with a gross weight of up to 650 tons and a speed of up to 125 km/h, or freight trains with a gross weight of up to 2,000 tons and a speed of up to 70 km/h in a single traction system. The locomotives of this series could also work in pairs in multiple timing and then the weight of the trains could be increased accordingly, even up to 3600 tons.

             Electric traction motors type EE-541A with a rated voltage of 1500 V had insulation made in class H (on a silicone substrate) with an acceptable operating temperature of 180 degrees Celsius. Each motor had 4 main poles and 4 commutation poles and a compensating winding in the main pole pole pieces. Such a winding is necessary when using a large weakening of the magnetic field excitation, which in these vehicles reached as much as 25%.

             The traction motors were also completely spring-loaded in the locomotive bogies, using Alsthoma type gears, and constitute an individual drive for the wheelsets by means of a toothed gear with a gear ratio of 79:18 in the Bo'Bo' axle system. The engines belonged to modern traction engines, which, among others, can be proved by the relatively low unit weight of the engine - 8.4 kg/kW.

             Together with the modern EU06 locomotives, a license for their production in the domestic industry was also purchased. This task was undertaken by the State Wagon Factory PAFAWAG in Wrocław, building almost identical visually and technically machines in 1963-74 under the designation of the EU07 series (factory designation 4E). Then, for almost a decade, the production of this series was discontinued in favor of the new series of ET22 electric locomotives. The project was resumed in 1983, when the Cegielski plant in Poznań (HCP) stopped the construction of the 2-section ET41 (203E) electric locomotives, which were derived from the EU07 series. And it was on the basis of the ET41 that the EU07 (303E) series machines were created in a completely new version. These vehicles have undergone many modifications and come in several versions (303E, 303Eb, 303Ec). Serial production continued until 1992. In the new construction, the previous self-supporting boxes were replaced with boxes with a sole bar and corrugated side walls, and larger scrapers were installed under the headstock. The new "sevens" were also adapted to the installation of an automatic coupler. In addition, the EU07 electric locomotives of all versions have multiple control sockets on both fronts of the box, thanks to which it is possible to drive two coupled locomotives of the same type by controlling both locomotives from the first cabin. However, due to some technical changes, the locomotives of the 303E series can only be combined with other 303E vehicles, while the electric locomotives of the earlier 4E series can only be combined with other 4Es, with a few exceptions.

             By changing the gear ratio from 79:18 to 75:22, EU07 machines could be adapted to a maximum speed of 160 km/h. It is currently 76:21.

             To sum up the differences in technique and appearance in EU07 version 303E and EU07 version 4E (thus EU06) the following changes were made:

Changing the timing (resulting in the possibility of multiple driving only within one type: 303E or 4E.
Type 303E has corrugated sheathing sheets (self-supporting body - structural element).
Service weight increased from 80 t (4E and EU06) to 83.4 t (303E).
The 303E locomotives, receiving a self-supporting body with a sole plate, prepared for the installation of an automatic coupler, are also longer - 16,235 mm in relation to the predecessor 4E (also EU06) - 15,915 mm.

                                                                                                           Norbert Tkaczyk

Pictures:
         Norbert Tkaczyk

Sources:

MSc. st. Kuczborski "25 years of PKP electrification" - WkiŁ, Warsaw 1963.
MSc. E. Mierzejewski "Electric locomotive series EU07" ("Rolling stock in the 40th anniversary of the People's Republic of Poland") - SIGNALS Weekly Railwayman No. 5/1985.
MSc. E. Mierzejewski "Electric locomotive series EU06" ("Rolling stock in the 40th anniversary of the People's Republic of Poland") - SIGNALS Weekly Railwayman No. 15/1985.
author's own materials.