MK3 Coach Whine Noise

NoOnesFool · 11 Jul 2019

One thing that I've noticed recently, with all the talk of HST PRM mods is that the noise as they arrive at a station is somehwat missing a whining sound that they used to make back in the 90s, see 1:05 at this video here. I've noticed that they still hiss but the distinctive whine has gone. Does anyone know the technical reason for this?

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hexagon789 · 11 Jul 2019

NoOnesFool said:
One thing that I've noticed recently, with all the talk of HST PRM mods is that the noise as they arrive at a station is somehwat missing a whining sound that they used to make back in the 90s, see 1:05 at this video here. I've noticed that they still hiss but the distinctive whine has gone. Does anyone know the technical reason for this?

It's the air-suspension if I recall correctly - the self-levelling valves I think. Don't know about the whine, your video doesn't seem to be linked I'm afraid.

TheEdge · 12 Jul 2019

That's most definitely the self levelling valves. If they've vanished from PRM modified Mk3s then it may be specific to the PRM work as the Anglia Mk3s, very much un-PRM, still make that noise.

aleggatta · 12 Jul 2019

I know the case with 377s is that the leveling valve filters are not accessible, and so they go between overhaul's without the filters being changed and so can whine a little more towards the end of the time period, so it might just be that during PRM work they have serviced the levelling valves

hexagon789 · 12 Jul 2019

TheEdge said:
That's most definitely the self levelling valves. If they've vanished from PRM modified Mk3s then it may be specific to the PRM work as the Anglia Mk3s, very much un-PRM, still make that noise.

I don't think they can have vanished, firstly because they are part of the suspension maintaining vehicle ride-height and secondly as they are part of the load-compensation for the brakes.

TheEdge · 12 Jul 2019

hexagon789 said:
I don't think they can have vanished, firstly because they are part of the suspension maintaining vehicle ride-height and secondly as they are part of the load-compensation for the brakes.

Possibly a new system for doing that is going in with the PRM mods? Or just a new valve that doesn't make the noise?

hexagon789 · 12 Jul 2019

TheEdge said:
Possibly a new system for doing that is going in with the PRM mods? Or just a new valve that doesn't make the noise?

I'd be more inclined towards the latter, considering there are a number of parts of Mk3s that are no longer manufacturered, it's seems likely enough this is another one which has had to be replaced by a new version.

samuelmorris · 12 Jul 2019

It's the most pronounced on Mk3s, but self-levelling noises are common on all sorts of other stock. 321s seem fairly prone to it, and when an electrostar experiences a significant loading change at a terminus (e.g. a 378 at Stratford or 357 at Fenchurch Street) it's also very pronounced there.

DarloRich · 12 Jul 2019

On the sleeper mkiii I was on last night there was a terrible noise on braking. It was like someone playing a violin. Awful!

( it could have been suspension related but only occured when the brakes were applied)

chubs · 12 Jul 2019

The GA Mk3's definitely whined when they stopped. Not paid enough enough attention to say if it's stopped since the latest mods.

47271 · 12 Jul 2019

The suspension wheezing I'm very familiar with and understand.

But there's another noise specific to mk3s or mk3 derived stock like 319s, and I've never been able to work it out - does anyone know?

It generally happens either at a stand or at very low speed, and of course this may be because I can only hear it when all other noise levels are low.

It's best described as a sort of restful mid pitched metallic twanging, up and down, not particularly loud. It used to be particularly noticeable on Thameslink 319s as they crawled through south London for example. I've also heard it on sleepers when they've been stopped for a period at say Crewe or Preston. As I say, it might be happening all the time but I can't hear it at speed.

It can't be aircon because 319s don't have it. It isn't traction because sleepers don't have it. Brakes?

Does anyone have any idea of what I'm on about?!

Bletchleyite · 12 Jul 2019

DarloRich said:
On the sleeper mkiii I was on last night there was a terrible noise on braking. It was like someone playing a violin. Awful!

( it could have been suspension related but only occured when the brakes were applied)

The whine is more like someone playing pan-pipes than that.

cjmillsnun · 12 Jul 2019

47271 said:
The suspension wheezing I'm very familiar with and understand.

But there's another noise specific to mk3s or mk3 derived stock like 319s, and I've never been able to work it out - does anyone know?

It generally happens either at a stand or at very low speed, and of course this may be because I can only hear it when all other noise levels are low.

It's best described as a sort of restful mid pitched metallic twanging, up and down, not particularly loud. It used to be particularly noticeable on Thameslink 319s as they crawled through south London for example. I've also heard it on sleepers when they've been stopped for a period at say Crewe or Preston. As I say, it might be happening all the time but I can't hear it at speed.

It can't be aircon because 319s don't have it. It isn't traction because sleepers don't have it. Brakes?

Does anyone have any idea of what I'm on about?!

It’s the Spirax valve. Used to drain moisture from the main res tank.

TRAX · 12 Jul 2019

Does anyone have a video where this is audible ?

samuelmorris · 12 Jul 2019

cjmillsnun said:
It’s the Spirax valve. Used to drain moisture from the main res tank.

This.

And a 321 example:

TRAX · 12 Jul 2019

TRAX said:
Does anyone have a video where this is audible ?

Sorry about the lack of precision, I was talking about the whine that started the thread.

samuelmorris · 12 Jul 2019

You mean this?

(42 seconds in onwards)

47271 · 12 Jul 2019

No not the spirax, I'm familiar with that on units and on locos, and that's more a clicking than a twanging, if you see what I mean! You wouldn't get that on a mk3 sleeper either I don't think.

My sound is a bit like pan pipes I suppose, but metallic rather than reedy, and it's continuous when it's happening. The pitch varies slowly, maybe rising and falling every three or four seconds. It isn't related to heavy braking like the din you get on mk2s but could be connected with application of the brakes in that I've only heard it either when at a complete stand or moving at speeds of 10mph or below.

I'll try and get a recording the next time I hear it.

DarloRich said:
On the sleeper mkiii I was on last night there was a terrible noise on braking. It was like someone playing a violin. Awful!

( it could have been suspension related but only occured when the brakes were applied)

As many times as I've been on a mk3 sleeper I've never got noise from the brakes other than when a mk2 has been next to my coach and I've been able to hear the racket from that distance. You can get a ghostly rising and falling tone which I've put down to the 67 as it takes power, you don't hear it with an electric loco up front. But that's more like a heavenly choir than an old violin! It sounds like there was something wrong with your coach!

TRAX · 12 Jul 2019

samuelmorris said:
You mean this?

(42 seconds in onwards)

Aren’t these just the brakes ?

Bletchleyite · 12 Jul 2019

47271 said:
My sound is a bit like pan pipes I suppose, but metallic rather than reedy, and it's continuous when it's happening. The pitch varies slowly, maybe rising and falling every three or four seconds. It isn't related to heavy braking like the din you get on mk2s but could be connected with application of the brakes in that I've only heard it either when at a complete stand or moving at speeds of 10mph or below.

Oh...that's probably the motor-alternator sets that convert the ETH input to the required voltage for the coaches, it does vary slightly in pitch with loading. You don't get it on HSTs as these are fed directly with the correct voltage.

The one I was thinking of (which I think is the same as in the video above) is the valves on the suspension, you hear it during braking as the vehicle moves forwards (down at the front, up at the back) as it brakes like a car does.

Actually, I just listened to the original video again and the sound at 1:05 is (a) an HST, and (b) is definitely the suspension levelling valves. The motor alternator sets are more of a hum of the electric motor.

samuelmorris · 12 Jul 2019

TRAX said:
Aren’t these just the brakes ?

No, if you carry on watching it's still going on when the train departs, that's air suspension levelling.

edwin_m · 12 Jul 2019

"it hissed when it moved and whined when it stopped and twanged when it stood still
I never knew just what it was and I guess I never will"...

Yes I know, getting coat.

47271 · 12 Jul 2019

Bletchleyite said:
Oh...that's probably the motor-alternator sets that convert the ETH input to the required voltage for the coaches, it does vary slightly in pitch with loading. You don't get it on HSTs as these are fed directly with the correct voltage.

The one I was thinking of (which I think is the same as in the video above) is the valves on the suspension, you hear it during braking as the vehicle moves forwards (down at the front, up at the back) as it brakes like a car does.

Actually, I just listened to the original video again and the sound at 1:05 is (a) an HST, and (b) is definitely the suspension levelling valves. The motor alternator sets are more of a hum of the electric motor.

It could be motor alternators I suppose, but would you get that on a 319? It's also got a sort of creaking quality to it. It isn't a fault because I used to hear it day in day out on slow moving Thameslink trains. I'm sure you get it when the train's off the juice. You don't hear it on more modern stock. It must be something to do with the brakes.

Anyway, I've taken us off topic because I'm describing a sound that isn't the one that this thread is aimed at, I think that one's been solved now...

Bletchleyite · 12 Jul 2019

47271 said:
It could be motor alternators I suppose, but would you get that on a 319? It's also got a sort of creaking quality to it. It isn't a fault because I used to hear it day in day out on slow moving Thameslink trains. I'm sure you get it when the train's off the juice. You don't hear it on more modern stock. It must be something to do with the brakes.

Anyway, I've taken us off topic because I'm describing a sound that isn't the one that this thread is aimed at, I think that one's been solved now...

Some 1970s-1980s EMUs did have motor-alternator sets, Merseyrail 50x certainly do though I forget if 319s do or not specifically. I think 319s and 321s may well not have, because they're almost totally silent when stationary, whereas on a 50x you've always got the background hum of the MA set.

samuelmorris · 12 Jul 2019

Bletchleyite said:
Some 1970s-1980s EMUs did have motor-alternator sets, Merseyrail 50x certainly do though I forget if 319s do or not specifically. I think 319s and 321s may well not have, because they're almost totally silent when stationary, whereas on a 50x you've always got the background hum of the MA set.

319s definitely do, I believe because of the DC components. 321s do not as they use the feed from the transformer. Whether the 319s use the MA when they're on AC power I don't recall, but I imagine it'd be simpler if they did.

See this video at 1m18 after the compressor cuts off, motor alternator still clearly audible after the train departs on AC, so I assume they were used all the time based on that.

MK3 Coach Whine Noise

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