Bell (railway)
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The chime is since the invention of the railroad an essential instrument for signaling certain information, especially for warning of dangers but also the announcement of the arrival of trains .
Basics
Like other components in the first railways, the chime as a manually operated mechanical bell was probably adopted by the stagecoaches and horse-drawn carts . With the development of the railway system , different areas of application emerged.
The bells used on the railroad usually emit a constant bell tone, which, depending on the construction, can have a range of up to three kilometers. But there were also chimes with two bell-shaped or differently designed resonance bodies , which then gave off different bell tones if necessary.
The bells at the railroad always had the task of attracting attention through an acoustic signal that was clearly distinguishable from other tones. Both for the information of the railway staff, in the predominant case, but for the travelers and other road users , the chime was a requirement for special attention and warning of the railway -related risk associated.
In contrast to the whistles , which are also used to signal trains , which led to considerable uncertainty and panic-like changes in movement, in particular due to very high-pitched, high-frequency sounds in animals ( work animals , draft animals in action near the railway line ) , the bell (from church towers ) known bell tone used. However, due to shorter intervals, the sound of railway bells differs significantly for humans from other bells (e.g. churches , fire brigade ).
Historical view
Development of the railway signaling system in Germany
Since December 7, 1835, the opening of the " Ludwigs-Eisenbahn " between Nuremberg and Fürth as the first German railroad, railways for the public transport of people and goods have been running in Germany . The first route was soon followed by many more, which were initially created separately from one another and only merged into a network over the decades. The early German signaling system had a peculiarity compared to the English one: while in England rail and road usually crossed at no level, the railway was always viewed in a condition that it was always passable and signals usually indicated free travel, in Germany it was level because of the many levels Level crossings necessary to secure these danger spots with a guard . In addition, in the early days, all German railway companies demanded that the guards revise the route between train journeys in order to be convinced of the safe condition of the route. This made the railway attendants the most important guarantors of a safe journey.
As long as the trains were moving relatively slowly and only on sight, later at a certain time interval, the guards kept receiving commands about their driving behavior and information about the condition of the train. The guards posted at a visual distance signaled the condition of the railway and the upcoming train journey to each other with flags, colored lanterns or horns like a relay. The term “continuous line signals” was created for these signals running ahead of the train. Every signal passed on was a confirmation that the train was "drivable". Balloon signals (1840) and wing telegraphs (1842) soon came up for this signaling . As “optical telegraphs” they transmitted the information about the condition of the railway , the running of the trains or operational issues such as requests for help or the like from one station to the next station via all guards.
The time for the railway attendant to be ready to transmit the signal was derived from the timetable . Unscheduled trains did not fit into this system because they were not expected. Therefore, they had to be announced by the scheduled train ahead (flag, lantern, signal disc on the locomotive and / or on the last car ).
Introduction of acoustic signals
With the increasing train density and the introduction of temporary driving, the risk that the railway attendants would miss a train journey increased. In fog or storm , the purely optical signal transmission no longer succeeded without interference. If the guards revised their section of the route during the train breaks and repaired minor damage themselves immediately, they would be canceled in the relay-like signal transmission from one post to the next. A signal to warn the railway and barrier guards was urgently needed.
In his lectures on railway construction, Eduard Schmitt comprehensively presented signaling around 1875 and explained why the bell signals in the group of acoustic signals were so important at the time under the aforementioned conditions.
Here are a few relevant passages:
“With the acoustic signals, the difference between daytime and nighttime signals disappears; they are always used in the same way. The means which are available for producing tones of some strength everywhere and easily without excessive costs are rather limited. Only the production of detonations is a simple means of signaling that can be used in most cases; however, it is expensive and allows only a very small number of signals. As a result, only the bells, whistles and horn (trumpet) tones remain. (...) The tones of the bells are also not audible over longer distances than the whistle and horn tones (in contrast to locomotive whistles / WL), unless the bells have an extremely large diameter. Audibility varies greatly depending on the circumstances. In a quiet night, under favorable conditions, with no wind, clear air, etc., the sound of a well-constructed horn can be heard for half a mile (1 mile on average 7.5 km / WL); Whistling will not be heard that far. The sound of large bells is heard two miles below the above-mentioned conditions.
However, the first requirement for signals intended for the railway company is that they are perceptible under all conditions; as a result of this condition, however, the use of acoustic signals is extremely limited. There is no acoustic signal given by the human respiratory organs which would remain reliably audible over 400 meters against storm winds, in rain and snow, etc. Bells of moderate dimensions reach at most twice this distance. (...)
The optical signals have the following advantages over the acoustic signals:
- The optical signal can be heard in large circles.
- The optical signals, if you let them stand, keep you informed of all happenings.
- The optical signal system allows a large number of characters to be formed with relatively simple means.
- The perceptibility of the optical signals is not impaired by unfavorable air currents, by loud noise, by howling of the storm, by thunderstorms, by the roar of the train, etc.; Acoustic signals are often inaudible under such conditions.
- The optical signals are easy to handle and easy to control.
In contrast, acoustic signals have the following advantages over optical ones:
- The acoustic signals are equally audible by day and night, in clear weather and in fog, snow flurries etc .; they always have the same shape. The optical signals often give rise to deceptions, especially in the dark.
- If the acoustic signals are formed according to correct principles, then they are either immediately understandable for everyone, even for the uninitiated, or they only require a small explanation.
- The acoustic signals attract attention by themselves.
- The acoustic signals allow an increase to a certain extent.
From what has been said, it can be seen that the field in which optical signals can be used is larger than that of acoustic signals. On the other hand, the acoustic signals are recommended to call up and arouse attention and, because they are easy to understand, to notify the audience. "
As early as 1841, the Taunus Railway from Frankfurt am Main to Wiesbaden was experimenting with mechanical bell pulls. A "loud sounding bell" was attached to a cast iron column. The guards operated a foot lever, and this transferred the movement to a brass wire cable located in protective tubes on the inside of the rail. There was only one signal “Attention!”. Since the timetable available to all items was still the only operational organizational means by which the operational sequence had to be based, this tone was sufficient. The fact that the tests were discontinued around 1843 was due to the fact that the kilometer-long lines were overloaded in bursts and could not withstand the loads. Dust, warmth, frost and moisture played their part. Nevertheless, the Taunusbahn deserves the credit of having invented the forerunners of the bell signals.
The disadvantages of optical signaling were:
- very susceptible to mix-ups due to handling and perception errors on the part of the many railway attendants
- very unreliable due to the highly weather-dependent transmission quality: snowfall, rain and fog reduced the visibility
- high personnel costs due to posting at visual distance
- Highest concentration requirement with the multitude of signal aspects and route revision and repair possible only during schedule breaks
- Due to the completely silent transmission of the optical line signals, there is an increased risk of overlooking unscheduled signals.
The alert tone was missing before the intended signal transmission began.
After the invention of the electromagnet, the first experiments with electrical current for the transmission of messages began around 1840. In the period that followed, electrical telegraph sets from various companies and systems were able to establish themselves on the railways. The best known and most common was the Morse apparatus, which had been in use for over a hundred years. With this new system of message transmission, a general three-way division of the signaling means emerged:
- From then on, the electric telegraph was used to transmit messages between the dispatchers at the stations (information about the train route, requesting help, announcing special trains)
- The form signals that emerged in their external form from the "optical telegraph" prevailed as the transmitter of orders from the route to the train crew (free travel, slow travel, stop)
- The information to the railroad and gatekeepers (announcement of train journeys, signaling of danger) could be transmitted to the electromechanical bell signaling systems, because they promised to best meet the requirements of the railroad practice:
- Safe effectiveness of the signal system at any time of the day or night, in all weather conditions and regardless of the season
- Connection of all railway and gatekeepers between two stations for simultaneous information about the departure and the direction of travel of a train
- Possibility of submitting reports from the train (ie via the posts) to the stations
This catalog of requirements, drawn up in 1846 by the Thuringian Railway Company, was the trend-setting for all developments in this field of electrical telecontrol technology. In June 1846, the Thuringian Railway Company was the first German railway company to put an electromechanical bell signaling system with 39 chimes into operation on the Halle - Merseburg - Weißenfels route and at the same time dispensed with the optical telegraph. On the other railways, too, the optical telegraphs for the railroad guards and gatekeepers gradually disappeared. The last of them are likely to have been dismantled at the end of the 1870s. The electromechanical bells had already proven to be a solid, uncomplicated and practical instrument that, contrary to all fears, worked flawlessly for a total of almost twelve decades - even in parallel with the later-emerging line telephones.
The sound of the railway bells differs from that of the other common bells in its group character: A "group" consists of five or six bells that are emitted on one bell, two or three bells. Railway bell signals consist of a certain number of groups: one group is called “Train journey from A to B”; two groups (approx. 3 seconds break between the two groups) means “train journey from B to A” (ie opposite direction); three groups mean “error, the signal just sent does not apply” (ie withdrawal of an incorrectly sent signal) and six groups mean “alarm! Something extraordinary has happened! ”(Ie close the barriers immediately and stop all trains still en route). If several stretches passed the guard post, the chimes differed in their sound pattern (number of bells, size of bells - i.e. pitch, type of strike - i.e. evenly or limping, etc.).
System of bells on railways
Bells are (or were) used on the railway for the following purposes:
- as a bell on rail vehicles
- as a manual bell (hand bell) for railway employees
- as stationary bells at train stations , stops and other operating points outside and inside buildings
Bells on rail vehicles
Bells on rail vehicles basically have the task of warning other road users (at level crossings, in town passages) and passengers on the platform of the approaching train or announcing the arrival of the train. Especially on branch lines and railways of minor importance, the use of a bell was preferable to the steam whistle because of the reactions of the farm animals mentioned.
Bells were only required by the operating regulations on branch lines . Locomotives intended for main lines only had to have a bell if the route of the train services regularly touched branch lines. If a branch line was only used in exceptional cases , bell devices operated manually by the engine driver or stoker / assistant could be used.
Simple, manually operated bells in the form of a bell, which were operated by an operator using a clapper, were already on the first locomotives in service. In the course of technical development, mechanical bells with different drive mechanisms (linkage, cable pull, belt drive) were initially used. However, all technical solutions as well as the hand bell proved to be impractical with the constantly increasing scope of operations.
In the mid-1880s, a fully usable solution was introduced with the patented Latowskische Dampfläutewerk .
The steam bell was based on the functional principle that controlled the extraction of steam from the steam boiler to the bell by means of a shut-off valve, and in this a spring-mounted clapper was lifted when the steam pressure was applied and after the steam pressure had escaped, the clapper would spring back to the bell. By means of the existing attachment points of the clapper hammer and the adjustability of the steam valve, it was ensured that different bell chime intervals were possible. The functional principle was implemented in different designs.
The availability of compressed air on the locomotives made it possible to use compressed air-controlled bells (e.g. Knorr type). The ringing is generated by a steel ball shot from the inside of the bell. The spring-loaded air chamber is closed again after the air in the chamber has escaped, the ball rolls again in front of the outlet opening and the air chamber is filled again via the air inlet opening. As soon as the air pressure in the air chamber overcomes the spring force again, the ball is thrown against the bell again.
With the availability of sufficient electrical power on the traction vehicles (diesel drive, electric drive), electric bells were used. The functional principle of electrical bells on the railroad corresponds to that of the bell . They differ from conventional bells only in the size of the necessary noise development.
Manual bells
Manual bells (hand-operated bells works or hand bells ) were used by railway employees, where special attention was required by the traveler. Especially before the departure signal, it was very common for the station master to use the hand bell to announce the imminent departure of the train.
The use of handbells is now limited to museum railways .
Stationary bells at operating points
In order to provide information about operational processes, stationary bells were activated between neighboring operational points via induction crank mechanisms. The stationary chimes were developed by the Berlin watchmaker Leonhardt. The Thuringian Railway was the first in Germany to equip its line with it. Bells were also used on the Gotthard Railway in Switzerland . Bells announced the departure of a train from one operating point to the next. There were stationary bells as
- Chimes
- Platform bell (platform bell)
- Chimes
- Bells at special operating points (tunnels, larger bridges with pedestrian areas, level crossings)
With the introduction of the line telephony, the stationary bell systems lost their importance, whereby the railway line telephone with different call signs for the respective stations of a route made it necessary to continue using these bell systems.
While the line telephones with connected bell systems have largely given way to standard telephones with built-in noise generators today, stationary bell rings are now almost exclusively found in level crossing safety systems.
literature
- Rudolf Heym: How does it actually work, the steam locomotive? Bruckmann, 2004, ISBN 3-7654-7255-7 .
- Author collective: Report on the German General Exhibition for Accident Prevention - Berlin 1889 . Volume 2, Carl Heymanns Verlag, Berlin 1891, p. 469 ff.
- Signal book. DR / DB
- Christian Ammann, Wolfgang List: Bell sounds along the rail. In: Railway amateur. 9/1992.
- Alfred Blum, Carl Georg Barkhausen, August Friedrich Wilhelm von Borries: The railway technology of the present. Volume 2: The Railway Construction of the Present. Section 4: Signaling and Security Systems. Wiesbaden 1904.
- Handbook of Engineering. Part V, Volume 6: Factory Equipment. 2. Dept .: Means to secure operations. edit v. S. Scheibner, F. Loewe, H. Zimmermann, Leipzig 1910/1913.
- L. Kohlfürst, KE Zetzsche: Handbook of electrical telegraphy. Volume 4: The Special Purpose Electric Telegraph. Berlin 1881.
- Wolfgang List: The chimes of the German railways. In: Railway Journal. 7/1993.
- Wolfgang List: KPEV chimes In: Railway Journal “Preußen-Report”. Volume 1.2, 1992.
- Wolfgang List: Chimes on the rail line. In: Rail transport currently. Vienna, No. 1/1996.
- Wolfgang List, Hans-Wolfgang Harden: Electromechanical bells of the railways. Verlag Bernd Neddermeyer, Berlin 2010, ISBN 978-3-933254-99-3 .
- Eduard Schmitt: Lectures on railway construction . 11th booklet: The signal system. Prague 1878.
- Eduard Scholkmann: The electric bells. In: The railway construction of the present. Section 4: Signaling and Security Systems. Part 2, Wiesbaden 1904.
- E. Schubert: The security works in the railway company. 4th edition. Wiesbaden 1903.
- Max Maria von Weber: The telegraph and signal system of the railways . Weimar 1867.
Web links
Individual evidence
- ^ Bernhard Püschel: Historical railway catastrophes. A chronicle of accidents from 1840 to 1926 . Freiburg 1977, ISBN 3-88255-838-5 , p. 8.