Steam whistle
The steam whistle is a technical device in which an acoustic signal is generated by means of highly compressed water vapor ( steam pressure ) (in the case of the railroad, a railway signal , in the case of steam navigation ; see below, e.g. fog signal, course signal, emergency signal , etc.).
Steam whistles are used in both stationary and mobile steam generation systems and, due to the use of the steam generated and stored for work purposes, they can be used as long as there is sufficient steam pressure.
In the case of railways , the steam whistle (if steam is available) or a comparable device (compressed air whistle , exhaust whistle ) for generating acoustic signals is prescribed by the Railway Building and Operating Regulations (EBO).
The functional principle of the steam pipe is based on the fact that water vapor escapes through a narrow gap against the edge of a pipe bell. The impacting steam stimulates vibrations in the air column in the bell (see organ pipe ), which are perceived as a whistling sound.
The steam whistle is operated in railway vehicles via a mechanical linkage from the driver's cab of the locomotive or railcar to the control valve between the steam supply line and the whistle. By means of the main valve and the additional valve, a different tone or different volume of the whistle signal can be generated by varying the dosage of the steam flowing through.
The arrangement of the steam whistle on locomotives of the railway differs greatly between the series . Arrangements on the driver's cab roof, in front of the driver's cab on the long boiler or directly above the smoke chamber are known.
Steam whistles and steam sirens were also used in steam shipping.
A steam pressure whistle that used to be very widespread is the whistle on the kettle . It gives a whistle as soon as the water in the kettle boils on the stove .
For the principle of the acoustic pipe, see organ pipe .