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Is that an easter egg? (SG2, MG2 groaning sound)

Posted: 15 Jun 2015, 20:24
by brozma
Hello everyone, one day I was having fun with SG2 on simvliet haven bridge loop track. I let it run in circles, then when I stopped the SG2 and wanted to leave it there staying I heard very loud groaning. It played for some seconds and then it cutted off and I could heard normal muted humming (when the train is powered from overhead wire or third rail and it's staying, you can hear a muted humming) I was wondering, "Why SG2 made that loud groaning? Wasn't that a system important for SG2? Why this groaning only sounds when the train is powered from overhead wire or third rail? Why only SG2 and MG2 (I discovered that MG2 does it too) make this sound?

For Michiel: I think, I dicovered an easter egg! 8-)

Re: Is that an easter egg? (SG2, MG2 groaning sound)

Posted: 15 Jun 2015, 20:34
by senjer
Thats the compressor of the train. They make this sound in real life. Because of that they had install couplers on the buffers at De Akkers.

Re: Is that an easter egg? (SG2, MG2 groaning sound)

Posted: 16 Jun 2015, 15:30
by metroverslaafde
Yes, it is a compressor. The doors on real the real MG2/SG2 close bij air pressure produced bij the compressor. To keep the doors closed the compressor needs to build up enough pressure to do so, that declares the sssssssssh noise when you close the doors, that is the airflow.

A video where you can hear the sound quite clearly:

https://www.youtube.com/watch?v=kviUHG_BXDk

Re: Is that an easter egg? (SG2, MG2 groaning sound)

Posted: 16 Jun 2015, 20:50
by atimur
metroverslaafde wrote:Yes, it is a compressor. The doors on real the real MG2/SG2 close bij air pressure produced bij the compressor. To keep the doors closed the compressor needs to build up enough pressure to do so, that declares the sssssssssh noise when you close the doors, that is the airflow.

A video where you can hear the sound quite clearly:

https://www.youtube.com/watch?v=kviUHG_BXDk
Also pressured air is used for brakes, that's the source of hissing sound when releasing them.

Re: Is that an easter egg? (SG2, MG2 groaning sound)

Posted: 17 Jun 2015, 05:05
by metroverslaafde
True, I forgot about that :)

Re: Is that an easter egg? (SG2, MG2 groaning sound)

Posted: 17 Jun 2015, 08:26
by atimur
metroverslaafde wrote:True, I forgot about that :)
Actually, it's the main use of compressed air, doors is only a side job. :)

Re: Is that an easter egg? (SG2, MG2 groaning sound)

Posted: 17 Jun 2015, 15:00
by Michiel
Actually these trains use electrodynamic braking by default, air brakes are only used at low speeds when the ED-brake is not efficient any more. And also the pantograph and third rail shoes are controlled by compressed air. This is the biggest loophole for these trains, if the air pressure is to low you have no power, and without power you cannot start the compressor to increase the air pressure. When this happens the trains requires 'CPR' to either manually supply it with power (the pole of the red flag below the third rail shoe does the trick, although I doubt it's very safe) or manually supply it with compressed air (basically using a big foot pomp) in order to get it up and running again.

Re: Is that an easter egg? (SG2, MG2 groaning sound)

Posted: 17 Jun 2015, 17:05
by MG2
Michiel wrote:When this happens the trains requires 'CPR' to either manually supply it with power (the pole of the red flag below the third rail shoe does the trick, although I doubt it's very safe) or manually supply it with compressed air (basically using a big foot pomp) in order to get it up and running again.
I had to do that a number of times. But it's a failure and shouldn't happen too often :mrgreen:

Re: Is that an easter egg? (SG2, MG2 groaning sound)

Posted: 17 Jun 2015, 19:28
by Maronit
atimur wrote: doors is only a side job. :)
Pun Intended?

Re: Is that an easter egg? (SG2, MG2 groaning sound)

Posted: 18 Jun 2015, 14:10
by brozma
Michiel wrote: When this happens the trains requires 'CPR' to either manually supply it with power
What is CPR? It's something like APU (auxiliary power unit) in aircrafts? Don't be surprised, I'm asking like that. I never have been in Netherlands and I'm not an engineer.

And Michiel: That's not an easter egg! I thought it is, but people here corrected me !