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The "Elektromote" trolley bus, 1882

1881: The "Elektromote"

In 1882, Werner von Siemens presented the world's first bus that ran from a power line suspended overhead – an invention that he had been working on for decades.


The vehicle, dubbed the "Elektromote," was supplied with electricity from an overhead wire, or “catenary.” A small, eight-wheeled "contact car" traveled along this double-pole cable, and served as a current pickup. Two copper cables connected the contact car to the vehicle, powering the two three-horsepower motors.


These gave the Elektromote an average speed of 12 kilometers per hour, at an operating voltage of about 550 volts DC. Although the trolley bus was more economical than rail vehicles, test runs were soon discontinued – mainly because the streets were simply too bad for it to run without constant disruptions.


Around 1900, engineer Max Schiemann went back to the idea, in collaboration with Siemens & Halske. Since the 1920s, trolleys running from an overhead catenary have become an important electric mode of transportation.

Traffic light at Potsdamer Platz, Berlin, around 1936

1924: Traffic light at Potsdamer Platz, Berlin

The first traffic signal system, running with gas light, was set up in London back in 1868. But it exploded shortly afterwards, killing a policeman. Not until 1914 was a traffic light installed once again, this time in the USA and using electric light. Siemens finally inaugurated Germany's first automated traffic control, at Potsdamer Platz in Berlin, in 1924. The signal lamps, aligned beside each other on a tower, were red, yellow and green.


The introduction of the light-emitting diode (LED) in the 1990s launched a new era in traffic light technology. LED signals need significantly less energy than conventional incandescent bulbs. And because LEDs have significantly longer service lives, they reduce operating and maintenance costs by eliminating the need for regular lamp replacements. Another advantage: modern LED optics offer maximum visibility in any weather, at any time of day or night.

The diesel catalytic converter, 1996

1996: The diesel catalytic converter

Siemens joined together with car maker Uni Cardan in 1986 to found a joint venture named Emitec, intended to concentrate on building catalytic converters. The venture was a success. The Emitec heated metal catalytic converter, developed in 1992, reduced pollutant emissions effectively, even during the cold-start phase.


In 1996, Siemens introduced a special catalytic converter for diesel engines that reduced the polluting nitrogen oxide content of exhaust gases by as much as 95 percent. Siemens' SINOx exhaust-gas management system optimized exhaust gas treatment for diesel truck engines. Among its features, the catalyst module reduced nitrogen oxide emissions by about 70 percent and soot by up to 50 percent, so that diesel trucks could comply with even the most rigorous NOx emission requirements.


In 2001, Siemens researchers combined a plasma process with a catalytic converter to finally provide a solution for diesel passenger car engines, meeting even more stringent exhaust standards.

Piezoelectric diesel injector, 2000

2000: World record piezoelectric diesel injector

In 1989, in response to the fast-growing role of electronics in cars, Siemens established a separate business unit for automotive technology. Besides individual components like air bags, ABS systems and navigation systems, the unit also made complete engine management systems. In 1992 it also began developing high-pressure diesel injection systems.


A key component of this "common rail" technology was the piezohy