Exhaust whistle
The exhaust pipe is a technical device for generating acoustic signals in railroad locomotives.
The railway building and operating regulations and the corresponding regulations for connecting railways require a device for giving acoustic signals for traction vehicles and auxiliary vehicles with power drive. These are designed as steam whistles for steam locomotives and generally as compressed air whistles for diesel and electric locomotives (also in the form of typhons / macrophons ), because these vehicles have a compressed air supply anyway due to the continuous compressed air brake.
Small locomotives with internal combustion engines (especially performance group I ) and light rail locomotives that have neither steam nor a compressed air system often have an exhaust pipe instead.
A valve can be operated from the driver's cab via a mechanical linkage that directs part of the exhaust gases to the whistle. The exhaust gases flow through narrow gaps against one or more pipe bodies (pipes or bells). The impacting gas flow generates - similar to an organ pipe - vibrations that are perceived as sound.