Friedrich von Hefner-Alteneck

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Friedrich von Hefner-Alteneck
Coat of arms of the von Hefner-Alteneck family
Grave in the old St.-Matthäus-Kirchhof in Berlin-Schöneberg

Friedrich von Hefner-Alteneck (born April 27, 1845 in Aschaffenburg , † January 7, 1904 in Biesdorf near Berlin ; full name Friedrich Franz Heinrich Philipp von Hefner-Alteneck ) was a German designer, electrical engineer and engineer and one of Werner's closest employees from Siemens .

Known to a wider public is Friedrich von Hefner-Alteneck by the eponymous lamp candlepower (NK), which in Germany, Austria and Scandinavia 1890-1942 luminous intensity unit Hefner lamp served (HK).

Beginnings

Friedrich Franz Heinrich Philipp was the youngest of the three sons of his father Jakob Heinrich . He was an art historian and later director of the Bavarian National Museum . However, this had no influence on the choice of profession, rather Friedrich began very early to tinker with all kinds of devices. So he went to school at the Technical University of Munich and the Polytechnic in Zurich, where he was mainly interested in lectures on the design of machines, less mathematical considerations. This was followed by a short internship in Munich.

Siemens & Halske

At the world exhibition in 1867, von Hefner-Alteneck was impressed by the "Telegraphenbauanstalt Siemens & Halske ", whereupon he applied to be a draftsman. However, no one saw any use for it, as engineers at that time had much more workshop experience. So on June 17th, 1867, he decided to start working in this company as a simple worker, quickly drawing attention to himself and being transferred to the new design office on September 30th. He quickly became head of the two-man office.

After Siemens had been entrusted with setting up the Indo-European telegraph line from London to Calcutta in 1868 , von Hefner-Alteneck made a significant contribution to its success. During this time he also significantly promoted the safety of railway operations by designing a bell signal mechanism and a speedometer and recorder. In 1872, at the age of 27, he became assistant to the chief engineer Carl Fischer (1830 to 1890), who headed the general technical management of the company. Von Hefner-Alteneck was responsible for the drafting and testing of the constructions and for the preparation of all working drawings.

From 1880 to the end of 1890 he was authorized signatory and manager of Siemens & Halske's Charlottenburg plant. After Werner von Siemens handed over the management of the company to his sons, von Hefner-Alteneck also withdrew from the company. He received numerous honors, including membership of the Prussian Academy of Sciences in 1901 and an honorary doctorate from the Technical University of Munich in 1897 . In the same year he took a seat on the supervisory board of AEG .

Box writer

Von Hefner-Alteneck achieved the breakthrough with his box writer, which brought great progress to the telegraph system. It was a type of typewriter that converted letters into Morse code so that the operator of a telegraph station did not have to be able to use Morse code . It consisted of a horizontally arranged box with pegs attached that could be moved using a keyboard. If you pressed a letter, the associated pens generated shorter or longer current pulses by scanning, according to the Morse code. This device received the greatest attention, Werner von Siemens wrote to his brother Wilhelm about it in April 1873: “... von Hefner has again beaten my chain writer by several lengths with his box writer. The thing works strangely precisely and beautifully ... Anyway, we have completely antiquated Wheatstone . "

The recorder was followed by other communications equipment, including tide curve printers, remote water level indicators and command devices for ships and mines.

Drum anchor

Siemens Hefner-Altenecksche dynamo machine with drum armature
Dynamo machine according to Siemens Hefner-Alteneck, in the Technical Museum Vienna

With the invention of electromagnetic self-excitation in 1866, Werner von Siemens laid the foundation stone for high- voltage technology : Motors and generators could now be built with acceptable levels of efficiency . However, the first machines were not yet perfect. One problem was their double-T armature , where numerous turns of the coils were unfavorably positioned. They hardly contributed to the energy conversion and produced unnecessary heat with their electrical resistance, which led to overheating. In 1872 von Hefner presented a much improved variant that for the first time allowed use over a longer period of time. With the drum anchor there was only one massive cylinder, which was wound in such a way that the windings on the cylinder jacket ran parallel to the axis. So there were practically only outer turns, the proportion of ineffective turns was significantly lower. This construction is still in use today.

Air coil machine

However, one problem remained with the drum armature: the strong heating of the armature iron caused by eddy currents . It meant a great loss of energy and caused such great problems that there was no avoiding water cooling. Von Hefner encountered him with the air coil machine, which received great attention at the World Exhibition in Vienna in 1873. With this construction, the armature stood still, the windings with the commutator ran around magnet coils and armature iron. To do this, a wire drum had to rotate quickly in a narrow gap, which required extremely precise production. In return, water cooling could now be dispensed with and the performance increased by more than five times. This design remained state of the art for a decade, then one had to revert to the old design for even larger engines. Now insulated iron windings were used, later the laminated dynamo sheets still known today , in order to reduce eddy current losses.

Differential arc lamp

In the early days of high- voltage technology, light always had to be generated with carbon arc lamps, and due to the complicated control mechanism required for operation, each lamp required its own generator. Von Hefner-Alteneck found a remedy here in 1878 with a self-regulating arc lamp, in which the distance between the carbon arc rods was readjusted to ensure a constant arc. It was shown at the Berlin trade exhibition in 1879 , then on the Berlin Kaiserpassage (intersection Unter den Linden / Friedrichstrasse ) and caused a sensation.

Although electric light only largely replaced gas light with the incandescent lamp developed ready for series production by Thomas Alva Edison , it already represented equal competition with the differential arc lamp .

Hefner candle

Hefner lamp (wood engraving 1897)

The competition between gas and electric light required a suitable unit for photometric investigations. In 1884 von Hefner-Alteneck suggested a glowing flame to the electrical engineering association as a comparison, which could be reproduced at any time. The physical-technical Reichsanstalt certified the new light unit, which was named after him Hefner candle .

Mignon

Von Hefner-Alteneck's last important invention was not of an electrical engineering nature: the Mignon pointer typewriter .

death

Friedrich von Hefner-Alteneck died unexpectedly of a stroke after a hunt in the villa of the industrialist Wilhelm von Siemens , in today 's Biesdorf Castle .

Honors

In Berlin-Siemensstadt , the street Hefnersteig honors Friedrich von Hefner-Alteneck. A street named after the engineer was also located in the industrial district of Berlin-Oberschöneweide . The Charlottenburger Hefner-Alteneck-Straße, named in 1924, fell victim to the S-Bahn construction in 1931 without replacement. His grave, an honorary grave of the State of Berlin , is located in the Old St Matthew Cemetery in Berlin-Schöneberg . In Munich there is the Hefner-Alteneck-Straße in the Isarvorstadt , which was named after him and his father. The Hefner-Alteneck-Straße in Aschaffenburg is only named after the father of the designer, Jakob Heinrich von Hefner-Alteneck.

literature

Web links

Commons : Friedrich von Hefner-Alteneck  - Collection of images, videos and audio files

Individual evidence

  1. ^ A gifted engineer - portrait of the inventor Friedrich von Hefner-Alteneck. Siemens Historical Institute, accessed June 14, 2019 .
personal data
SURNAME Hefner-Alteneck, Friedrich von
ALTERNATIVE NAMES Hefner-Alteneck, Friedrich Franz Heinrich Philipp von
BRIEF DESCRIPTION German designer and electrical engineer
DATE OF BIRTH April 27, 1845
PLACE OF BIRTH Aschaffenburg
DATE OF DEATH January 7, 1904
Place of death Biesdorf near Berlin