Comparison of Class 68 noise levels with other locomotives

[samuelmorris]

By the same token, Voyagers, 185s etc. are an order of magnitude louder at idle than Sprinters despite the newer design due to the combination of larger engines and higher idle speed. The idle speed of old BR locomotives is quite comical really, so it's not surprising they're quieter until under power. Frankly I'm dubious the engine revs need to be as high as they are at idle on modern units and locos, I'm sure there must be a more efficient way of doing it. I assume it has something to do with rpm / AC output frequency ratios (in much the same way gensets operate at 1500rpm as it's half of 50Hz).

 

[sjpowermac]

I can only provide an educated guess as I'm not involved with these locos in any way. I have studied them in the past using info I've found online.

The driving controls signal to the VCU (vehicle control unit), the two traction converters have controllers which controls the alternator output, traction motors power and auxiliary power and also the engine via it's ECM (engine control module). Each of these communicate on a CAN-Bus so there will be automated logic in the way that these demands are handled. The engine will probably speed up initially for anti-stall purposes and when loaded (electrical load on the alternator) will dip in RPM, once all is settled the engine speed, alternator output and IGBT frequency will be at the mercy of the driver's request (with the VCU actually doing the calculations).

This is actually similar to a loco from the 60s, except they use old fashioned mechanical and electrical control gear rather than electronic signals!

Thank you very much for that, all makes sense. I’ve read about the power unit, alternator and traction motors, but hasn’t found anything about the control system. Thank you for the great summary.

 

[sjpowermac]

Spot on it's a manual operation, but look on the cab end of the DT and the sticker warns the loco must be disconnected before the shore supply is fitted. This would add a lot of time to the procedure.

Thank you for that. The turn around time at Liverpool Lime Street is 24 minutes. I suspect that by the time passengers have disembarked, plus allowing time for boarding, then we are likely down to 10 to 12 minutes max anyhow. I’m in complete agreement with you, shutting down is a total non-starter

 

[sjpowermac]

Thanks - how big is one of those? Unfeasible to fit anywhere on a TPE set without a new carriage?

I suspect that’s a complete non-starter in terms of space. As mentioned above, turn around time at Liverpool is 24 minutes (assuming an on time arrival). I think Marylebone is probably different in that the houses face directly on to the railway. Even there the 68s power up a fair while before departure, about 20 minutes I think.

 

[sjpowermac]

The initial rev up is the reverser being placed into forward.

Many thanks for that, greatly appreciated.

 

[37057]

By the same token, Voyagers, 185s etc. are an order of magnitude louder at idle than Sprinters despite the newer design due to the combination of larger engines and higher idle speed. The idle speed of old BR locomotives is quite comical really, so it's not surprising they're quieter until under power. Frankly I'm dubious the engine revs need to be as high as they are at idle on modern units and locos, I'm sure there must be a more efficient way of doing it. I assume it has something to do with rpm / AC output frequency ratios (in much the same way gensets operate at 1500rpm as it's half of 50Hz).

Choosing the right speed is quite important and besides, the minimal speed will be set by the OEM. Too slow and you have low frequency noise and rattles through the car body, increasing the speed will reduce this but can then introduce other problems such as turbocharger failure.

Thank you very much for that, all makes sense. I’ve read about the power unit, alternator and traction motors, but hasn’t found anything about the control system. Thank you for the great summary.

Some links to geek out on;

https://library.e.abb.com/public/a6..._High_Power_ABB_Traction_System_Eurolight.pdf
https://www.selectron.ch/en/news/ne...-3-2015/Diesel-electric-locomotives-in-UK.php
http://www04.abb.com/global/seitp/s...4e00501c63/$file/AC+800PEC+control+system.pdf
https://library.e.abb.com/public/052b9ad954dd455cb4ae3a5eef4c9a4c/BORDLINE CC1500 DE_M_1800 Eurolight RevC EN.pdf
https://library.e.abb.com/public/bb...4ebc72/Railvolution03-10-Traction-package.pdf

 

[Grannyjoans]

Class 37's aren't loud when idling, it's only when they start moving when they are loud!!

92's could easily be the loudest locomotive at a standstill. Especially when they first come to a stand just after they've been working hard, with the fans on full blast. Nothing else makes that much noise when at a standstill.

66's are surprisingly loud at tickover. The constant yinging can be heard above almost anything else. However, when powering up, they don't really come close to the 68's and the BR Diesels.

 

[Grannyjoans]

I can see that ‘Noisegate’ is gathering some momentum so here are a few stats, all in dBA min/max

Class 91
64.4/97.5
(Stood in station/powered up)

Class 68
(engine idling/engine powered up)
82.4/93.8

Class 37
(engine idling/engine powered up)
72.9/100.4

All recordings made from the yellow line on the platform.

Class 91 is very nearly as loud as a 37 when powering up!
Only difference is it's just a vacuum cleaner type sound instead of the growling clagtastic thrash.
Still far more character than the EMU's that are replacing them.

I would like to see the figures from other locomotives.

I would almost certainly bet that the Class 68 is the loudest diesel that's been built since the Class 56.

 

[Grannyjoans]

That was the thing that surprised me most, the rail/wheel interface can produce far higher noise levels than a diesel locomotive.

That screech made by a 142 round that curve between Salford Central and Man Vic is deafening!
Those noise levels certainly exceed anything made by a locomotive and not in a good way!!

 

[gimmea50anyday]

Noise wise the sounds of a 68 compares to a 70 and a Deltic from what I have heard, and listening to one under the roof of York this morning sounded very throaty and powerful. Volume wise however many heritage classes such as the aforementioned deltic, class 37, valenta HST, have sounded far louder and yet were tolerated on a day to day basis. Even a 185 in full cry sounds louder than a 68. As a part time DJ (hence my well known nickname amongst TPE staff) I pick up on subtle differences in sound and to me it's the fans and auxiliaries that make the sound of a 68 loud over the throbbing growl of the engine itself

 

[gimmea50anyday]

Still far more character than the EMU's that are replacing them.

On a jolly to North Berwick the other day and the noise from the traction motors on the 385 I was on was actually quite varied and interesting to listen to, especially after Drem loops and the curve on to the branch

 

[Grannyjoans]

Chopper's (Class 20's) were always one of the loudest engines!
When leaning out of the front window, they were always a favourite on heritage lines! They seemed to make a lot more noise than the larger engines when powering up the branch.

 

[sjpowermac]

Choosing the right speed is quite important and besides, the minimal speed will be set by the OEM. Too slow and you have low frequency noise and rattles through the car body, increasing the speed will reduce this but can then introduce other problems such as turbocharger failure.



Some links to geek out on;

https://library.e.abb.com/public/a6..._High_Power_ABB_Traction_System_Eurolight.pdf
https://www.selectron.ch/en/news/ne...-3-2015/Diesel-electric-locomotives-in-UK.php
http://www04.abb.com/global/seitp/s...4e00501c63/$file/AC+800PEC+control+system.pdf
https://library.e.abb.com/public/052b9ad954dd455cb4ae3a5eef4c9a4c/BORDLINE CC1500 DE_M_1800 Eurolight RevC EN.pdf
https://library.e.abb.com/public/bb...4ebc72/Railvolution03-10-Traction-package.pdf

Thank you so much that. Finishing the reading list, that’s going to keep me busy!

I’ve just read the one about the AC 800PEC control system, that’s exactly what I was interested to find out about.

Thank you so much for taking the time to share those.

 

[sjpowermac]

Noise wise the sounds of a 68 compares to a 70 and a Deltic from what I have heard, and listening to one under the roof of York this morning sounded very throaty and powerful. Volume wise however many heritage classes such as the aforementioned deltic, class 37, valenta HST, have sounded far louder and yet were tolerated on a day to day basis. Even a 185 in full cry sounds louder than a 68. As a part time DJ (hence my well known nickname amongst TPE staff) I pick up on subtle differences in sound and to me it's the fans and auxiliaries that make the sound of a 68 loud over the throbbing growl of the engine itself

Completely agree with all you’ve put there. The 68s sound fantastic under that station roof at York.

 

[sjpowermac]

Regarding Deltics, the main 'humming/droning' sound when idling is the air reverberating in the engine air intakes on the side above the nameplates, that's why you can feel the air in your lungs vibrating when stood there. It's also why they sound different under an overall roof as the two intakes either side harmonise together. The other principle sound at idle is the phasing gears. Only when really opened up can you hear the exhaust note.

Thank you for that. I often wondered why you could actually ‘feel’ the sound of a Deltic.

Pic attached of one of my early encounters with a Class 55. As a kid I loved standing next to the air intakes. Please forgive the flares

 

[ac6000cw]

the "baby" deltics were turbocharged but weren't too successful I've often wondered what we'd have had if EMD's pressure charging arrangement of a supercharger and turbocharger had been available back then. That's the arrangement where the turbo takes over from and declutches the supercharger at higher revs and engine loads, allowing more power to be available at the output shaft. At least 2000bhp per engine? And quieter exhaust too.

In the 'The Deltics - A Symposium' book, there is information on a proposed Super Deltic with two 18 cylinder turbocharged engines rated at 2200hp each - and later marine engine versions got up to 2500hp.

 

[sjpowermac]

Interesting thread. My 385 came into platform 12 of Waverley last week, and I could tell that there as a Fife Circle 68 over the other side of Waverley even before I stepped off the train. It isn't loud perhaps, but the sound is somewhat unique and seems to cut through other noise. Presumably it is rich in the sort of frequencies and harmonic content that are absent in the 'note' of other trains? I like the sound but it is hard to miss; somewhat like having a chinook flying around.

Completely agree, the 68 makes a great sound. Interesting that you mention Edinburgh Waverley, I had my first haulage off one from there. I was with my wife, and didn’t want to push the train thing too far, so we were in the main waiting room when the ecs for Glenrothes arrived. There was no problem hearing the 68 even from there!

 

[Alanko]

Completely agree, the 68 makes a great sound. Interesting that you mention Edinburgh Waverley, I had my first haulage off one from there. I was with my wife, and didn’t want to push the train thing too far, so we were in the main waiting room when the ecs for Glenrothes arrived. There was no problem hearing the 68 even from there!

I need to find an excuse to jump on a 68-hauled Fife service while I still live in Edinburgh. They appear to be either slightly too early in the morning for regular comfort or quite inconveniently around dinner time. I would probably take myself off to Dalmeny and then kick my heels for a bit.

 

[Cowley]

@sjpowermac I’ve got a few observations to make from quite a few years living less than a couple of hundred metres away from Cowley Bridge Junction.
These are purely anecdotal of course but it may be of interest.
We have quite a decent variety of passing trains and they’re generally accelerating away from Exeter, or slowing down for the station stop (unless they’re running on or off the Barnstaple line).
I can almost always tell what’s passing from the noise because it bounces across the valley, and I’ll run through some of them here:

class 143 - noisy engines, and a good amount of flange squeal as they turn on or off the Barnstaple line, very distinctive.

class 150 - very noisy engines, the sound seems to carry very clearly for quite a while, but no squealing wheels.

class 158 - much quieter than the above!

HST short sets and XC sets - a nice quiet low resonant rumble from the MTUs as they accelerate past, very smooth, and the mk3s are definitely quiet when going over the points compared to other stuff.

IETs - Pretty quiet actually. Slightly louder than the HSTs over the points, but the engines (although at a higher pitch) are quieter (possibly because they’re spread out throughout the sets).

220/221s - The noise of the engines carries quite well, but the noise of the wheels hitting the points of the junction is for some reason far louder than any of the other wheelsets that pass here. They make a real clattering sound.

class 57s on the sleepers - being so late at night the sound carries quite well. They’ve got a nice meaty sound compared to the units.

classes 59 and 66 - That yinging tickover cuts through everything. I can hear them ticking over even indoors, and when they open up with a heavy freight they’re actually quite loud. But not as loud as a:

class 37 - on an NR test train. They are still astonishingly loud, and if the wind is in the right direction you can still hear them growling away for a good few minutes after they’ve gone past.

There’s other stuff too including railtours etc, but these are the most frequent things that I notice day to day.

 

[Grannyjoans]

Class 150's are the loudest trains on the network to travel on in terms of engine noise. Incredibly loud!
Yes a locomotive engine is louder overall but you can't hear it much as you will be in a separate hauled coach!

Loudest overall has got to be the 142 screech on certain curves. Absolutely deafening.

 

[Grannyjoans]

Places like Liverpool Lime St mentioned above or Man Vic, and many others are now home to more electric trains than ever before, or somewhat quieter DMUs and haven't seen diesel loco hauled trains in some time. People will have got used to a lot less noise.

Class 150s/156s and 185's are loud out of Lime St and Man Vic and have been around for some time. They're probably amongst the loudest DMU's I can think of.
The 68 sound is much nicer and has much more bass. It's a sound worth listening to which makes a change around here.

It is great that Clagtastic thrashing traction is making a small comeback to places which haven't seen it in many years, in the form of 68's on TPE services. Few years ago I would never have thought this could happen!

The yinging of a 66 doesn't do much for me.

 

[sjpowermac]

@sjpowermac I’ve got a few observations to make from quite a few years living less than a couple of hundred metres away from Cowley Bridge Junction.
These are purely anecdotal of course but it may be of interest.
We have quite a decent variety of passing trains and they’re generally accelerating away from Exeter, or slowing down for the station stop (unless they’re running on or off the Barnstaple line).
I can almost always tell what’s passing from the noise because it bounces across the valley, and I’ll run through some of them here:

class 143 - noisy engines, and a good amount of flange squeal as they turn on or off the Barnstaple line, very distinctive.

class 150 - very noisy engines, the sound seems to carry very clearly for quite a while, but no squealing wheels.

class 158 - much quieter than the above!

HST short sets and XC sets - a nice quiet low resonant rumble from the MTUs as they accelerate past, very smooth, and the mk3s are definitely quiet when going over the points compared to other stuff.

IETs - Pretty quiet actually. Slightly louder than the HSTs over the points, but the engines (although at a higher pitch) are quieter (possibly because they’re spread out throughout the sets).

220/221s - The noise of the engines carries quite well, but the noise of the wheels hitting the points of the junction is for some reason far louder than any of the other wheelsets that pass here. They make a real clattering sound.

class 57s on the sleepers - being so late at night the sound carries quite well. They’ve got a nice meaty sound compared to the units.

classes 59 and 66 - That yinging tickover cuts through everything. I can hear them ticking over even indoors, and when they open up with a heavy freight they’re actually quite loud. But not as loud as a:

class 37 - on an NR test train. They are still astonishingly loud, and if the wind is in the right direction you can still hear them growling away for a good few minutes after they’ve gone past.

There’s other stuff too including railtours etc, but these are the most frequent things that I notice day to day.

Thank you so much for that. Interesting what you say about how the sound of a 37 carries, I live about 200m from York station and would completely agree with you on that!

What a beautiful place Cowley Bridge Junction is. In 1985 I had a couple of weeks staying at the University of Exeter (Duryard Halls I think) and the Class 50s past there were amazing, particularly at night! I spent most of the evenings at Cowley Bridge.

Thank you again for sharing your thoughts and information, greatly appreciated.

 

[sjpowermac]

Class 150s/156s and 185's are loud out of Lime St and Man Vic and have been around for some time. They're probably amongst the loudest DMU's I can think of.
The 68 sound is much nicer and has much more bass. It's a sound worth listening to which makes a change around here.

It is great that Clagtastic thrashing traction is making a small comeback to places which haven't seen it in many years, in the form of 68's on TPE services. Few years ago I would never have thought this could happen!

The yinging of a 66 doesn't do much for me.

I completely agree with all you’ve put there. It’s absolutely fascinating seeing the introduction of brand new loco hauled services and great we have such charismatic locos too!

 

[londonmidland]

Dependant on location but at Birmingham New Street, the Voyagers are by far the loudest train you’ll hear there. Exaggerated by it being an underground station.

Even with its very low speed through the station, it still gains enough speed for the engines to vibrate anything close by to it. You can ‘feel’ it in the air.

Idling is considerably loud too, before it revs down after a while.

 

[Cowley]

Thank you so much for that. Interesting what you say about how the sound of a 37 carries, I live about 200m from York station and would completely agree with you on that!

What a beautiful place Cowley Bridge Junction is. In 1985 I had a couple of weeks staying at the University of Exeter (Duryard Halls I think) and the Class 50s past there were amazing, particularly at night! I spent most of the evenings at Cowley Bridge.

Thank you again for sharing your thoughts and information, greatly appreciated.

No problem, actually it was fun thinking about it.
Around 1985 we used to camp in my friends garden near Clyst st George, and you could hear the class 50s on the Waterloo route heading out through Broadclyst, but you could also hear them running up the river from Starcross towards Exeter. The deep thudding noise they made when being worked hard carried for miles and miles on a still night.

 

[Meerkat]

As a kid I could clearly hear the 50’s on their way to/from Exeter from my bedroom over a mile away the other side of town

The good old ‘Network Express’ that stopped over 15 times!

 

[Alanko]

92's could easily be the loudest locomotive at a standstill. Especially when they first come to a stand just after they've been working hard, with the fans on full blast. Nothing else makes that much noise when at a standstill.

I heard this for the first time a few months ago during the hot weather. The Caledonian Sleeper service was coming into Waverley at around 7:20 am. Suddenly there is a sound like a giant Flymo powering up. Surprising, head-turning levels of noise.

 

[Sapphire Blue]

Living within earshot (but sadly not sight) of the Milnsbridge viaduct, some personal observations.
I could always hear the locos heading up the valley towards Standege.
The 158s were almost inaudible either way.
The 185s I can hear heading down to Huddersfield - very distinctive whine.
The 68s I can hear in both directions - beautiful.

 

[xotGD]

there is a sound like a giant Flymo

Surely a sound like a giant Dyson?

 

[samuelmorris]

Surely a sound like a giant Dyson?

To be fair it does actually sound a lot like a hover mower now I think about it, far moreso than a vacuum.
Best illustration of that sound appearing I can find is 2m16 in this video