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What is it that gives moving trains their signature sounds?

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hexagon789

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So many things:

Engine types
Transmission
Brakes
Traction motors
Traction motor blowers
Bogies

I always find that a 158 has a strangely distinctive rolling noise, I can tell it's a 158 from how it sounds rolling along against other types of train. Possibly the make-up of the wheels?
 
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I'd say vented brake discs create a distinct rolling sound on units such as 158s/390s etc
 

KevinTurvey

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Just my observations but I remember WCML expresses passing at speed and the quite extreme difference in noise level each bogie type made when there were Mk 1 2 and 3 in the same train; B4 and Commonwealth at speed were significantly louder than the BT10.

I think today the sound of the Pendolino bogies remind me of the original BR1 bogie sound.

I think the rain also makes a difference, wet wheels make less noise.
 

Highlandspring

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I used to love the sound of the T68 trams flying along on the “roaring rails” between Bury and Radcliffe. Caused by corrigations on the extremely worn railheads I think?
 

snookertam

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What is it that causes the alarm type sound on the 380s (and I think other desiro units?). Have never heard another type of train make a sound remotely like it. Also noticeable is that the pitch seems the change at around 15mph.
 

hexagon789

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What is it that causes the alarm type sound on the 380s (and I think other desiro units?). Have never heard another type of train make a sound remotely like it. Also noticeable is that the pitch seems the change at around 15mph.

Combination of the traction motors and the Insulated Gate Bi-polar Transistor traction electronics I believe. All the Desiro EMUs have that distinct sound as far as I'm aware.
 

AM9

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Combination of the traction motors and the Insulated Gate Bi-polar Transistor traction electronics I believe. All the Desiro EMUs have that distinct sound as far as I'm aware.
As has been mentioned on more than one thread before, it the deliberate modulation of the switching frequency of the inverters. In order to reduce the impact of interference from switching transients, it is desirable to spread the energy of the transients over a wideer frequency band. To do this, the actual frequency is continually changed. On the latest Desiro EMUS (the class700/717s) the modulation is only applied when operating on DC lines. Under ac, the supply feeding the inverters already has a large 50/100Hz ripple which spreads the transients' energy enough anyway. Under ac, OLE, the Desiro Cities make a continuous higher frequency audible tone. This has a modulation on it (50Hz) which is sufficient to lower individualcomponents of EMI (Electro-Magnetic Interference) to levels that the signals & comms. infrastructure can operate in.
 

hexagon789

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As has been mentioned on more than one thread before, it the deliberate modulation of the switching frequency of the inverters. In order to reduce the impact of interference from switching transients, it is desirable to spread the energy of the transients over a wideer frequency band. To do this, the actual frequency is continually changed. On the latest Desiro EMUS (the class700/717s) the modulation is only applied when operating on DC lines. Under ac, the supply feeding the inverters already has a large 50/100Hz ripple which spreads the transients' energy enough anyway. Under ac, OLE, the Desiro Cities make a continuous higher frequency audible tone. This has a modulation on it (50Hz) which is sufficient to lower individualcomponents of EMI (Electro-Magnetic Interference) to levels that the signals & comms. infrastructure can operate in.

Thank you for the detailed description, my technical knowledge on the subject is rather limited but I can understand use if a wider range of frequencies to mitigate against interference. That much my brain can handle!
 

anamyd

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380s have an alarm sound on leaving .
385s have a distinctive sound upon departing .
158s whine .
156 thrash and groan.
350s, 360s, 444s and 450s also have the "alarm" sound, not just 380s. and other classes with the same engines as 156s (150s, 153s, and 155s) also "thrash and groan". Have you never left Scotland...? :lol:
 
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