scotrail class 156

[doningtonphil]

Hello

I asked 2 questions in the timetables section about a Carlisle a Glasgow service I saw at Carlisle yesterday. The 2nd question is probably more relevant here.

The Scotrail class 156 made a noise every couple of minutes like several air valves firing, and then again a few seconds later.

What was making the noise?
Thanks

 

[scotraildriver]

a sticking compressor unloader valve

 

[doningtonphil]

It seemed to be coming from both vehicles, within a second or two of each other, as if it was supposed to be doing it, like on a timer

 

[455driver]

Was the train stationary in the station at the time?
If so then it is just the water trap (or whatever its called) releasing the moisture it has trapped from the compressed air systems.

 

[driver9000]

a sticking compressor unloader valve

Agreed. Common enough fault.

 

[doningtonphil]

Its defo not the compressor governor. Both vehicles, two distinct sounds pef vehicle at the same time

455driver. Yes it was stationary. Do 455s have a similar system? I know a lot of DMUs have norgren filter systems on their air system, but that doesn't drain every couple of minutes.

 

[455driver]

455driver. Yes it was stationary. Do 455s have a similar system? I know a lot of DMUs have norgren filter systems on their air system, but that doesn't drain every couple of minutes.

Not really sure, I would think so as the air supply is pretty much the same on 150s and 455s.

 

[Geeves]

I believe it was after the aftercooler mod that the 156s received they started making this sound but how it relates to that component I dont really know

I know the sound like 3 or 4 high pitched air releases within a few seconds of each other.

The Northern ones all make this sound too so I guess the same mod is being done on the Scotrail ones maybe at Heaton.

http://members.madasafish.com/~dysgraphyk/156/class156_underframe.htm

Second to last picture that part is now different, no more pipes, just a smallish box.

 

[driver9000]

I believe it was after the aftercooler mod that the 156s received they started making this sound but how it relates to that component I dont really know

I know the sound like 3 or 4 high pitched air releases within a few seconds of each other.

The Northern ones all make this sound too so I guess the same mod is being done on the Scotrail ones maybe at Heaton.

http://members.madasafish.com/~dysgraphyk/156/class156_underframe.htm

Second to last picture that part is now different, no more pipes, just a smallish box.

The small box in the photo is the heating/ventilation box. The Aftercooler pipes are to the left of the image and are still there on the 156s I've seen recently.

 

[doningtonphil]

Geeves

That sounds like it. So its a mod on the after cooler. You say the after cooler is the pipes, do you mean that 'helter skelter' of tubing in the bottom photos?

 

[driver9000]

Geeves

That sounds like it. So its a mod on the after cooler. You say the after cooler is the pipes, do you mean that 'helter skelter' of tubing in the bottom photos?

Yes that is the Aftercooler pipework.

 

[scotraildriver]

And now they overheat...... great mod that

 

[Peter Mugridge]

Not really sure, I would think so as the air supply is pretty much the same on 150s and 455s.

I think they do - I've often seen and heard 455s releasing puffs from the valves on the undersides of the carriages.

Also, many years ago I was going out with someone who worked as a tester at the Martonair plant near Farnham; she recognised their valves on the 455s. ( Martonair were later taken over by Norgren ).

 

[doningtonphil]

And now they overheat...... great mod that

what overheats? The air system or the engine? Like you say, great mod. Not sure how the engine overheating can be linked to the air system though?

 

[simon7929]

The Northern units have just started doing this! I noticed one doing it earlier this year and assumed it was some kind of fault! They're all doing it now so must be a new mod!