I was using my new phone when I delivered this new thread. It is touch screen and I am still not used to it so prefer to write in as few words as possible. I realise it isn't very clear though...
I refer to Southern 313s. This 'drill' seems to recur at regular intervals. I realise the 313s are old and have different electrical motors? However the noise is the loudest I have experienced on any mainline train and quite obtrusive.
Regarding 158s I refer to Arriva Trains Wales (ATW) units. I did not mean to join threads on this matter but I had trouble finding the old thread and I'm eager to see the first pics! Will have to continue to wait then :P
--- old post above --- --- new post below ---
I should think the drill sound is the compressor running, they are quiet noisy on 313's.
Sorry what is a compressor?
Also I have DMU and EMU handbooks so will not be asking how many 444s there are though I admit to being obsessed with the workings of these trains