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Since 2014, Siemens has been building test routes for trucks that draw their power from overhead contact wires. The eHighway concept represents a first step toward the electric freight transport of the future and toward a completely new area of applications for overhead wires. All this got off to a rather inconspicuous start more than 130 years ago – with a retrofitted horse-drawn carriage. This debut marked the birth of the trolleybus and laid the foundation for a new type of motorized transportation.
On April 29, 1882, an open hunting carriage in Halensee near Berlin caused great astonishment. The vehicle moved forward without being drawn by horses or running on rails – as was customary at the time. Instead, observant bystanders noticed the cables leading to an electric overhead line that caused the vehicle to move. It has been more than 130 years since the first electric bus in the world successfully complete its inaugural run. On the roughly 540-meter test route in Halensee – on what is now the Kurfürstendamm, one of the city’s main boulevards – Werner von Siemens presented an invention he had been working on for decades. The company’s founder had described his idea to his brother Wilhelm as early as 1847: “When I have time and money, I want to build an electro-magnetic hackney that will never leave me in the lurch.” This plan became reality in the early 1880s.
To achieve this goal, Werner von Siemens rebuilt an open hunting carriage so that it could move without horses or rails. This vehicle, which made history under the name of “Elektromote,” was supplied with electric power via an overhead line. A small eight-wheel contact vehicle moving along this bipolar cable served as a current collector. The device had to be separately weighted to keep it from toppling off the overhead line. Two flexible copper cables connected the contact vehicle to the carriage. These cables conveyed power down a wooden mast mounted on the carriage to the two electric motors beneath the driver’s seat, which drove the rear wheels via steel chains; a functioning differential had not yet been developed.
The two three-horsepower motors with an operating voltage of 550 V direct current enabled the vehicle to reach an average speed of 12 km/h. Drivers determined the direction of travel by means of a steering mechanism on the front axle, but they had little maneuverability because they had to keep alongside the 50 steel masts which carried the overhead line. To generate the electricity, the head engineer at Siemens & Halske, Carl Ludwig Frischen, had built a small power plant in a nearby shed. It
consisted of a steam engine connected to a dynamo.
Despite this progress, the Elektromote never advanced beyond the initial stages, although Werner von Siemens obtained permission from the city of Berlin in October 1881 to build a test route for the vehicle – albeit with the injunction that he “must kindly ensure the necessary precautions are taken to prevent any accidents as a result of the operation of the steam engine (for generating electricity) and the road vehicle.” Even though “trackless trolleys” were less expensive than rail vehicles, Werner von Siemens stopped the test runs in Halensee in the middle of June 1882. The reason was the poor roads, which presented numerous hindrances to the progress of the carriage. There were also no rubber tires for vehicles at that time. In addition, the mid-1880s saw increasing electrification of horse-drawn streetcars, and the design of the electric streetcar was being technically refined during the same period. Trackless trolley technology was then forgotten for a while.
Today, technology that uses overhead wires to power busses electrically is still being used widely. Nevertheless, just as was the case with Werner von Siemens more than 130 years ago, the people at today’s Siemens are again a step ahead in their thinking. In 2014, the company installed the world’s first eHighway: in between the two largest ports in the U.S. – in Los Angeles and Long Beach, California – eHighway trucks equipped with hybrid drives and smart pantographs (current collectors) are traveling along a one-mile test route without producing any local emissions. The vehicles draw their power from a catenary system (overhead wires). Similar test routes have been installed in Europa for the first time, with Sweden taking the lead in 2015, and Germany following in 2017. The ten-kilometer eHighway test route on Germany’s A5 Autobahn between Frankfurt Airport and Darmstadt will go into operation at the end of 2018 – as yet another milestone on the road to the electric freight transport of the future.
Ulrich Kreutzer | Ewald Blocher
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