Tower clock
on the clock tower of the Palace of Westminster in London (incorrectly called " Big Ben " )
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A clock tower is a large, highly visible, usually in a church tower or clock tower built in clock . As a rule, dials are attached to all four sides. The dial does not necessarily have to be placed on a tower. The entire clock mechanism, i.e. the clockwork with the additional components, a large clock on a public building such as a town hall, a school or a castle is also referred to as a tower clock.
history
Striking clocks
Tower clocks were the very first mechanical clocks and were widely used towards the end of the Middle Ages . Clocks were very expensive at that time, so a tower clock was useful for all residents of a place. As central and authoritative time indicators, these clockworks were installed on the high towers of churches, town halls and castles. The first weight-driven wheel clocks (from around 1300) initially announced the full hour with automatic bells. Alternatively, tower guards would strike the church bell at the beginning of each hour .
With the invention of the strike clock, it was possible for the first time to always display equinox hours of the same length with the help of a mechanism without having to perform astronomical calculations. A mechanical clock with a display of the previously common temporal hours , which varied in length from year to year, would have been very complex, although its construction was tried in isolated cases. Beat clocks in connection with equinox hours are first documented in Padua in 1344 . Genoa followed in 1353, Bologna in 1356. As a result, strike clocks were used throughout Europe .
Clocks with hands
Later clocks with hands were also used. They brought an "official" time that was binding for the respective region. With the first dials, they were content with just one hand that counted the hours. The tower clocks were still traditionally handcrafted from iron by blacksmiths.
When using Roman numerals on the dial of clocks, the 4 is often shown as 'IIII' and not as 'IV', as was often used since the late Middle Ages according to the rule of subtraction . The 9, however, mostly as 'IX'. There are different explanations for this. One is based on symmetry reasons. The 'IIII' creates a visually equivalent counterweight to the 'VIII' on the opposite side. In addition, all types of numbers appear equally often in this way (four dash, V and X numbers each). Both spellings are common.
Tower clocks were used to divide the time for liturgical purposes (the times of prayer ) and to divide the working day. A very early German-language instruction manual for regulating a tower clock with a so-called "balance beam escapement" is known from the year 1385. For a long time, these clocks were reset every day according to a sundial or a noon , not necessarily because they were imprecise, but because the true local time , which was newly determined daily according to the position of the sun, was used until the 19th century .
Age of electrification
The mechanics of the central large clockwork, which have been tried and tested for centuries, remained largely unchanged , depending on the manufacture and regional influences. With the introduction of electricity and the desire to automate visible and audible processes of telling the time, there were a number of modifications to existing clockworks. Various patent specifications and new designs were presented at the world exhibitions.
Electromechanical drive (elevator)
Up to now, the weights for driving the movement, pointer and chime have been laboriously wound up separately or combined using a hand crank with rollers, pulleys and differential gears. From now on, this was done by an electric motor with a reduction. As before, the required motor control was carried out via the clockwork with an additional built-in disc. A release pin, which took into account the free fall of the weight and activated and switched off the winding motor via a mercury liquid switch, determined the individual winding of the watch. (See video Wikipedia clockwork electromechanical clockworks, mechanical clockworks with electric winding, tower clock Villa Haas electromechanical winding (Perrot company))
Electromagnetic control (impact)
In order to convey the right sense of time even at night, most tower clocks had striking mechanisms . Many designers used a second electric motor in order to avoid a potentially annoying overlap between impact and drive. Another technical challenge was the striking mechanism control of two different bells for quarter and hour strikes. (See striking mechanism (clock) Wiener Schlag) The second electric motor drives a hammer lifting shaft via a V-belt as before. A magnetic coil controls the deflection of the bell hammer that is required and is connected to a rope. From rack strike movement are electromechanical contactors the number of strokes imparted to time.
present
Today mechanical tower clocks are rarely in use. The modern technology with radio-controlled movements and also the complex, difficult maintenance of the watches have made their contribution. As a result, many historic tower clock movements are worn out due to neglect or, because they are no longer needed, have been sold to private hands. On the other hand, historical tower clocks are increasingly being viewed and restored as technical monuments. By retrofitting with electrical elevator devices, the effort for their operation can be significantly reduced without having to change the historical clockwork. The accuracy is also acceptable after a thorough restoration.
Inverted hands
The church tower clock of the parish church Maria Himmelfahrt in the South Tyrolean community Terlan shows, unlike today, the minutes with the short clock hand and the hour with the long hand. Before the introduction of the more accurate pendulum clock at the end of the 17th century, there were only hour hands due to the inaccuracy of the clockwork . The old large hour hand was left with the parish church in Terlan when a small minute hand was added later - to differentiate it. The same procedure was followed for the Graz clock tower on the Schlossberg in Graz and the old large hour hand was left in place. On some tower clocks, an additional dial was attached for the minute or quarter hour display that was added later.
record
For Mecca , Saudi Arabia , Johannes Perrot's family business in Calw produced a tower clock with four faces with a diameter of 43 m, which it claims to be the largest clock in the world. The tower is 601 m high, the Makkah clock was installed by a Turkish company, as only Muslims are allowed into the holy city.
See also
- History of timing devices
- Astronomical clock
- Precision tower clock of the Grand Temple in La Chaux-de-Fonds by Collin, Paris (1860)
literature
- GW Rösling, B. Stoss: The Thurm clock building on its current… . 1843; Reprint, Verlag Historische watch books , Berlin 2006, ISBN 3-9810461-1-0
- Curt Dietzschold : The tower clocks including the so-called art clocks . Weimar: Bernhard Friedrich Voigt, 1894.
- Knut Deutschle: The old tower clocks . Rockenhausen 1989, ISBN 3-87022-129-1
- Bernhard Schmidt: Tower clockworks . Edited by DGC Tower Clocks, Günter Verlag, Georgsmarienhütte 2001, ISBN 3-9807704-0-0
- Jürgen W. Schmidt: The municipal clocks of Perleberg and their supervisor 1806-1817 , in: Communications of the Association for the History of Prignitz Vol. 6, Perleberg 2006, pp. 145-150
- Friedrich-Karl Ginzel: Handbook of mathematical and technical chronology II - The time calculation system of the peoples: time calculation of the Jews, the indigenous peoples, the Romans and Greeks as well as supplements to the 1st volume , German book export and import, Leipzig 1958 (reprint first edition Leipzig 1911), pp. 93-94.
Web links
- Publications on the subject term tower clock in the catalog of the German National Library
- Search for tower clocks in the German Digital Library
- Search for tower clocks in the SPK digital portal of the Prussian Cultural Heritage Foundation
- Expert group tower clocks in the DGC
- Tower clocks in the Deutsches Museum
- Tower clocks in the Hessenpark open-air museum
- Tower clocks in the Bockenenem Tower Clock Museum
- To the development of the clock tower watch hanger
- Museum for Time in Rockenhausen
Individual evidence
- ↑ a b Gerhard Dohrn-van Rossum : The story of the hour , Hanser 1992, ISBN 3-446-16046-9
- ↑ Pierer's Universal Lexikon, Volume 17. Altenburg 1863, p. 572. Thurmuhr at Zeno.org
- ↑ Fritz von Osterhausen: Callweys lexicon . Munich 1999, ISBN 3-7667-1353-1 , p. 337
- ↑ Instructions for use for regulating a tower clock ( Memento from December 3, 2013 in the Internet Archive ), Memento, Staatsarchiv Luzern
- ↑ The clock tower of the parish church
- ↑ Graz old town clock tower
- ↑ Barbara Auer: The largest tower clock in the world comes from Germany aktiv-online.de, April 4, 2013, accessed on August 19, 2018.