sexta-feira, 5 de novembro de 2021

Relógio astronómico do Museu Alemão de Relojoaria de Glashütte em manutenção, após 17anos a trabalhar ininterruptamente

Uma das principais atracções do Museu Alemão de Relojoaria, em Glashütte, Alemanha, o chamado “relógio astronómico e artístico”, foi para manutenção, um trabalho efectuadio a cada 15 ou 20 anos. A última intervenção foi em 2004.

O relógio foi criado entre 1892 e 1925 pelo mestre relojoeiro Hermann Goertz, que trabalhou em Glashütte a partir de 1918. O Estado livre da Saxónia adquiriu-o em 1929, por 15,000  Reichsmark, doando-o  à escola de relojoaria local, que desde 2008 alberga o museu.


Explica-nos o museu:

What happens during the revision?

Supported by the findings of the previous revisions, a plan of the work to be carried out  was drawn up before the start. This time it was again determined to document all work steps in detail so that they can be made available for future revisions. At the beginning of the current revision, the movement and the dial were removed from the mount in the wooden clock case. For the first time in 17 years, the movement was visible again. After the movement had been taken to the watchmaker's workshop and after an intensive study of the overall construction and the functional processes, dismantling began. The removed parts are now examined and checked for signs of wear or damage. If defects are found (e.g. broken jewels, damaged teeth on pinions or wheels), the necessary measures are taken. It is always crucial to proceed as carefully and as true to the original as possible. All parts of the movement are cleaned. If oxidation is found, appropriate preservation measures are taken. In further steps, functional surfaces, such as the running surfaces of the shafts, are elaborately polished. The parts are precisely measured for documentation.

The results obtained from this also allow conclusions to be drawn about the functional relationships in the movement. During the subsequent reassembly of the movement, it is now important to perfectly coordinate the interplay of the parts. This ensures the functional processes until the next revision.



Previous revisions

The current revision is the fifth since the clock was completed in 1925. The previous overhauls took place in 1938, 1956, 1984 and 2004. In 1956 it was carried out by the Glashütte master watchmaker Alfred Helwig, who also redesigned the display of the moon phase. Instead of the original lunar disc, he used a rotating sphere that now presents the phases of the moon even more clearly. This representation was already favored by Goertz after the clock was completed, but could no longer be realized by himself. In order to design the watch for a very long service life with the greatest possible revision intervals,

Hermann Goertz had taken appropriate precautions when designing the movement. The bearings and pivots of the watch were designed in such a way that they ensured that the oil would hold for a long time. The running surfaces are extremely hard and have an excellent polish, which minimizes signs of wear and tear. In addition, the majority of the wheels and levers were designed so that they could be dismantled to allow cleaning and re-gilding of the wheels. 



Technical data of the art clock

The watch is a superlative in all respects. The monumental case made of mahogany wood  measures 250 x 150 x 50 cm in height, width and depth. The drive mechanism weights for the movement and striking mechanism weigh 12.5 kg and 20 kg, the second pendulum weighs a total of 12 kg. The striking mechanism strikes the number of hours with a double stroke every quarter of an hour and every full hour with a single stroke. The movement and the dial together have 1,756 individual parts; including 122 wheels and pinions, 54 levers and springs, 13 jewels (bearing stones) and two jewel pallets of the lever, 424 screws and nuts, 17 hands, two display discs, three number rings and one display sphere. At that time, around 700 parts were required for the manufacture of the dial alone. A total of 20 pieces of information can be read on the dial, which has eight individual dials for the time, calendar and astronomical displays. This includes hours, minutes, seconds, a perpetual calendar with details of the day, day of the week, month, year, leap year, the equation (equation of time) and the power reserve displays for the movement and striking mechanism. The astronomical displays show the age of the moon, the course of the moon, the moon phase, the times of sunrise and sunset with the mean Glashütte local time. Also the starry sky, which shows the currently visible part of the starry sky over Glashütte and the real position of the sun in relation to the constellations and in the zodiac maps.






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