What's the sound that makes HST's sound like EMUs?

[RichW1]

Hi all, just wondering what the whirring sound is on mark 3's (that never used to be there years ago) that makes the HST's sound like EMU's?

The engine's themselves are so quiet now compared to before and they sound like a little bit like they're almost AC electric cooling equipment when they pull out or in a station now - no fun compared to the old. I know we have to get rid of them in the end but I'd prefer they sounded and stayed as they were until scrap time!!! Anyway I digress...any ideas would be welcome!

 

[northwichcat]

The EMT HSTs make a similar ticking sound to the Merseyrails 507/8s when they're 'cooling down.'

 

[devon_metro]

Probably the electric Traction Motors

 

[RichW1]

electric traction motors? Why have they got them of carriages now when they didn't used to? As the HST moves off and the mark 3's pass they sound just like 313's years ago pulling off when I was a kid...same sound just slightly less noisy!

 

[LexyBoy]

Could it be air being released from the brakes? Though that's more of a whining sound than a whirring...

Other auxiliary motors? fans?

 

[RichW1]

I know the sound you mean about the air from the brakes. This sound's like some sort of mini motorised sound just like you get in some suburban emu stock. It's about twice along the train. Someone must know. I'm sure I never used to hear it but maybe that's because the HST's were louder drowning out the carriage sound?! I don't know what it is but I also sat over wherever it was on the coach a few weeks ago and if I didn't know my trains I would've thought I was in an electric train with the dulled quite high pitch sound like a motor as described above.

Really want to know what this is!

 

[moonrakerz]

AirCon packs ?

 

[Hydro]

Possibly transformers for electrical equipment?

 

[route:oxford]

Hi all, just wondering what the whirring sound is on mark 3's (that never used to be there years ago) that makes the HST's sound like EMU's?

Think I know the sound you mean...

It tends to be after a brake application. You get the kind of whoop noise and it feels like there is a motor running under the Mark3. I've always guessed that it was a compressor for the brakes or aircon.

 

[silentone]

I'm sure what your talking about is a result of the acceleration of the train and the increased supply of power to each carriage as the train accelerates so things like the air con (as it's most noticeable) sound as if it's working harder.

If you've ever been in the kitchen this would also be the point that the equipment starts heating up. i.e the element in the toaster will suddenly glows

 

[John Webb]

When re-engined in recent years was the control system for the traction motors altered? Just that some control systems can make noises as they adjust the electrical power going to the motors.

 

[Kingfisher200262]

The only rotating machine on a Mk III HST trailer is the ventilation fan in the air con unit. These have changed in recent years on some (but not all) TOCs' HSTs from dc to ac motors, which may have modified the sound.

If we're talking loco hauled Mk IIIs (Norwich - London, sleeper services or Pretendolino) then it's probably the motor alternator (MA) set, which develops 415 V three phase from the 1000 V ETH supply.

 

[317666]

Judging from the NXEA loco-hauled Mk3s, it's just the sound that the wheels make on the rail, because the DVTs have a different type of bogey and make a different noise on the track.

 

[323235]

Could it be Roaring Rail?

If it is then here's an explanation someone wrote on another forum a few years ago to explain how it occurs:-

Train axles do not have differentials i.e gearing to allow an outer wheel on a curve to move the greater distance than the inner one. As the train rocks from side to side the bogies yaws (moves left and right) down the track. The outer wheel during the very short yaw movement cannot keep up with the inner wheel and skids slightly. After a period of time a chequer board effect can be seen on the rails. It causes very slight ridges due to the uneven wear and as a train rubbles over it it causes the roaring rail (sometimes called howling wheel in other countries).

Multiple units seem to be the main cause of the effect but all trains make the sound once the rail has been rippled. It is also more common on curves but it can be found on straights too.

You also get two different types of sound depending whether the rail is jointed (fishplates) or continous weld.

 

[TomJ93]

roaring rail?

 

[kestrel]

If the railgrinder has recently done the track then you'll get an unusual sound as the train moves off

 

[devon_metro]

electric traction motors? Why have they got them of carriages now when they didn't used to? As the HST moves off and the mark 3's pass they sound just like 313's years ago pulling off when I was a kid...same sound just slightly less noisy!

Ah sorry, thought you were referring to the whine from the powercars.

The sound you speak of sounds like the AC air con fans as people have already mentioned. They 'rev' with the engine.

 

[HST-DAVE]

.. agree, sounds like compressor motors/pumps on air con and/or brakes.. The loco hauled Norwich - London trains also have the additional noise of 'flat spots' on wheels, last couple of journeys it were like they had square wheels on the carriage I was in.
clunk, clunk, clunk, clunk, tap, tap, tap, ting, ting, noise and vibration varies with speed

 

[RichW1]

Thanks for the info guys...by the way, seems odd as intercity's never used to sound like this! I'm sure they had aircon in the 80's and early 90's even if they didn't have sockets and lately tv's!

Oh yeh, and as for the 90's, yeh I noticed this too....why the hell has the sound on all these trains got worse?! I was on the Bristol Parkway to Paddington the other day...track quality is appalling compared to the 90's and the 'billiard table' before that! Why can't we just get level track anymore?! Anyway I digress once again!

 

[Kingfisher200262]

Thanks for the info guys...by the way, seems odd as intercity's never used to sound like this!

This seems to confirm that the sound you've noticed is the change to ac fan motors on the air con units, which happened from the early part of the 2000s.

 

[No Fault Found]

The only rotating machine on a Mk III HST trailer is the ventilation fan in the air con unit. These have changed in recent years on some (but not all) TOCs' HSTs from dc to ac motors, which may have modified the sound.

If we're talking loco hauled Mk IIIs (Norwich - London, sleeper services or Pretendolino) then it's probably the motor alternator (MA) set, which develops 415 V three phase from the 1000 V ETH supply.

And the toilet extractor fans

 

[Kingfisher200262]

And the toilet extractor fans

Good point. Don't think that the toilet fan makes it sound like an EMU however.

Actually, thinking about it, I'm not sure that an HST toilet has an extractor fan!

 

[Class41]

I was similarly puzzled years ago while on an HST Mk3. An electrical sounding whine from below, not related to road speed, nor engine speed.
It transpired the rail grinder had been working that line. As the grinder proceeds, its grinders rotate at a given speed creating grinding marks on the rail head, the mark spacing increases with the linespeed of the grinding train. As you travel over the newly ground rail, a whine is generated, whose pitch varies according to the pitch (spacing) of the grinding marks.
I did hear a tale of a depot's whole fleet being out of service while driver's reports of "Electrical noises underneath" were being investigated, then someone twigged the grinding train had been visiting!

 

[Wyvern]

Could it be Roaring Rail?

If it is then here's an explanation someone wrote on another forum a few years ago to explain how it occurs:-

If you get roaring rail of that kind in this day and age there is something seriously wrong.

British Rail cured it in the sixties as part of the development of high speed goods and passenger trains.

 

[No Fault Found]

Good point. Don't think that the toilet fan makes it sound like an EMU however.

Actually, thinking about it, I'm not sure that an HST toilet has an extractor fan!

It certainly does have a toilet extractor fan.

But no, probably doesn't make it sound like an EMU

 

[TGV]

I was similarly puzzled years ago while on an HST Mk3. An electrical sounding whine from below, not related to road speed, nor engine speed.
It transpired the rail grinder had been working that line. As the grinder proceeds, its grinders rotate at a given speed creating grinding marks on the rail head, the mark spacing increases with the linespeed of the grinding train. As you travel over the newly ground rail, a whine is generated, whose pitch varies according to the pitch (spacing) of the grinding marks.
I did hear a tale of a depot's whole fleet being out of service while driver's reports of "Electrical noises underneath" were being investigated, then someone twigged the grinding train had been visiting!

The pitch varies as the wheel negotiates a curve in the track also - you'll notice that the pitch increases as the effective conicity is increased during curve transition and decreases as it blends back into straight again. It can sound very similar to a smooth electric motor whine.