BTB E2E
The BTB E2E, also known as F 2/2 and De 2/2, were a pair of Swiss electric locomotives operated by Burgdorf Thun Bahn in the early twentieth century. They are the oldest three phase locomotives designed for full service operation that have been preserved. The locomotives were built by Brown, Boveri & Cie and Schweizerische Lokomotiv- und Maschinenfabrik and entered service in 1899. They were powered by two 750V AC electric motors which drove two axles. A two speed gearbox enabled the locomotives to travel at and, the latter for passenger transport. The gearbox was later upgraded, raising the speed to. Relegated to secondary duties when more powerful designs were introduced, the locomotives provided valuable service until 1930.
Description
Constructed in Switzerland by a collaboration between Brown, Boveri & Cie, who provided the mechanics, and Schweizerische Lokomotiv- und Maschinenfabrik, who contributed the electrics, the two E2E locomotives were introduced to pull goods on the BTB. They were equipped with two 19-pole electric motors with a one hour rating of which powered a common shaft mounted on an auxiliary frame. Power was transmitted via a countershaft and coupling rods to two axles to power four driving wheels. The railway operated at 750V three phase AC, which was transmitted to the locomotive via a roof-mounted pantograph and overhead wires. The locomotives were equipped with a 100 V circuit for lighting, heating and other auxiliaries.The E2E had a wheelbase of and a total length of. Weight in service was. A driving cab with simple controls, including air brakes, was fitted to one end of the superstructure. A two speed gearbox, switchable when the locomotive was stationary, was fitted. The lower gear allowed a maximum speed of on a slope of 25 ‰ drawing a load of. The higher gear was designed for the locomotive to travel at up to.
The gearbox proved to be problematic and was revised by SLM in 1900. Later, the gearing was changed to allow for a higher speed of.