How did Class 360s get their speed uprated from 100mph to 110mph maximum?

[railfan458sw]

class 90 has top speed of 110mph and the 360s have a tops speed of 110mph but they got a speed boost how does trains do this and another example why didn't they give a speed boost to the 700s like the 387s

 

[swt_passenger]

I can explain the 360s, they really just had hardware modifications to the original motors, as had already been done to the various 350s operated by LM. If you are aware of the parts of a 3 phase motor, their rotors had to be strengthened for increased forces at the higher speed. They’d have needed resulting changes to software, and possibly the pantographs but I’m not sure about that latter area.

 

[Ken H]

class 90 has top speed of 110mph and the 360s have a tops speed of 110mph but they got a speed boost how does trains do this and another example why didn't they give a speed boost to the 700s like the 387s

think they have the power for higher speeds. But some bits of the trains are not. Running electric motors at speeds higher than specification may damage them, so may need a modification. Similarly, pantographs. May need a fix to the retardation settings of the brakes.

 

[railfan458sw]

I can explain the 360s, they really just had hardware modifications to the original motors, as had already been done to the various 350s operated by LM. If you are aware of the parts of a 3 phase motor, their rotors had to be strengthened for increased forces at the higher speed. They’d have needed resulting changes to software, and possibly the pantographs but I’m not sure about that latter area.

so the 350 deserios can do 110mph and higher top speeds

 

[swt_passenger]

so the 350 deserios can do 110mph and higher top speeds

Yes, IIRC the first batch of Desiros to be done retrospectively were the 350/1s, for the Trent Valley services that ran on the fasts rather than via Northampton. 350/2 were done a bit later, and I think the last batches were done in manufacture. Speed limit is still 110 though. I believe the gangways and crash worthiness rule out higher speed running.

 

[railfan458sw]

another question i was on a 700 and it has a stop speed of 100mph in the cab it says 100mph max speed but it was doing and holding 104 and 107mph(on my phone between finsbury park and stevenage) ive seen this in yt vids and on my spedometer they can do over 100mph? seen this with the 444 700 and other trains that do 100mph

 

[physics34]

another question i was on a 700 and it has a stop speed of 100mph in the cab it says 100mph max speed but it was doing and holding 104 and 107mph(on my phone between finsbury park and stevenage) ive seen this in yt vids and on my spedometer they can do over 100mph? seen this with the 444 700 and other trains that do 100mph

The speed limit displayed is the design speed for that unit not necessary the max speed it can actual reach.

 

[JN114]

another question i was on a 700 and it has a stop speed of 100mph in the cab it says 100mph max speed but it was doing and holding 104 and 107mph(on my phone between finsbury park and stevenage) ive seen this in yt vids and on my spedometer they can do over 100mph? seen this with the 444 700 and other trains that do 100mph

There’s a wide margin of error in handheld GPS on phones and the like; I wouldn’t take for granted any speed readings they may be giving.

 

[railfan458sw]

There’s a wide margin of error in handheld GPS on phones and the like; I wouldn’t take for granted any speed readings they may be giving.

i also came across a very accurate one and it was doing higher than 100mph

 

[Ken H]

i also came across a very accurate one and it was doing higher than 100mph

GPS needs to 'see' satellites in a wide arc across the sky to be accurate. in a train it can only 'see' satellites in a narrow arc through windows, so struggle to be accurate. They cant 'see' through the metal of the roof.

 

[Hadders]

The only place where 700s could run above 100mph is for a few miles between Finsbury Park and Woolmer Green (where they switch to the slow lines). Someone else will know but 125mph doesn't start until north of Woolmer Green. The time saving would be a few seconds at most.

 

[Magdalia]

Your right to speed is your ability to stop.

Before any other considerations come into play, the train brakes must be able to stop the train within the standard signal spacings.

On OHL routes the interaction between the pantograph and the OHL is particularly important, especially on multiple unit trains with more than one pantograph. This has been an issue on the GN out of Kings Cross for many years. The class 387s had to have new pantographs when they came to Hornsey.

My understanding is also that there is no 125 mph track south of Woolmer Green, though I've not checked for a long time, and almost always travel on trains only permitted to do 100 mph. The constraints of operation through the 2 track section mean that 125 mph, or even 110 mph, has limited value south of Woolmer Green.

In ye olden dayes, before "black box" recorders on trains, the 1 in 200 falling gradients on the GN were conducive to very fast running if the conditions were right. But timing of trains at speeds of around 100 mph is a challenge because of the tiny margins for error, whatever the timing equipment. GPS is particularly unreliable on the south end of the GN because of the large number of tunnels. The best guide for the passenger of fast running on the south end of the GN is the pass to pass time between Potters Bar and Hatfield, which is almost exactly 5 miles, so needs to be covered in significantly less than 3 minutes.

Timing of trains at 100 mph has been controversial since City of Truro in 1904!

 

[aleggatta]

On OHL routes the interaction between the pantograph and the OHL is particularly important, especially on multiple unit trains with more than one pantograph. This has been an issue on the GN out of Kings Cross for many years. The class 387s had to have new pantographs when they came to Hornsey..

Just a correction here. Whilst it was initially suggested the pantographs would be changed for the same type that was already operating on the GN, this did not happen, instead the existing pantographs were validated with the ECML wiring. The only 387’s that had their pantographs ‘downgraded’ were the ones supplied to c2c, and as far as I am aware had to have their top speed reduced to reflect this. Happy to be corrected if the c2c units can run at 110, but all the /1s and /2s have the same pantograph type as new.

 

[Magdalia]

The picture evidence suggests that the pantographs were changed. 387104 was the first unit on the GN to be used for driver training and here has a new pantograph:

387104 LET 3C91 CBG-KGX crew-training 29-8-16

On 29 August 2016, 387104 passes Letchworth on 3C91 Cambridge - Kings Cross crew-training.

www.flickr.com

Further, it is different from the pantograph that it had when working on the MML:

https://www.flickr.com/photos/johnfrombedford/21795660354/

There are "bobbly bits" on the ends of the contact arm in the GN picture that are not present in the MML picture.

 

[Ken H]

Just been discussing this with family. There was a new verb. to red star. and talk of 'red staring' stuff!

 

[D365]

The speed limit displayed is the design speed for that unit not necessary the max speed it can actual reach.

Correct. And in some cases they are faster than the design speed of the train. Just like on a car.

 

[aleggatta]

The picture evidence suggests that the pantographs were changed. 387104 was the first unit on the GN to be used for driver training and here has a new pantograph:

387104 LET 3C91 CBG-KGX crew-training 29-8-16

On 29 August 2016, 387104 passes Letchworth on 3C91 Cambridge - Kings Cross crew-training.

www.flickr.com

Further, it is different from the pantograph that it had when working on the MML:

https://www.flickr.com/photos/johnfrombedford/21795660354/

There are "bobbly bits" on the ends of the contact arm in the GN picture that are not present in the MML picture.

The two photos show the same pantograph. I appreciate that with the photo from the MML, the pantograph is hard to see, but if you look closely you can see the arc horns on both images. the pantograph on the units has always been a Brecknell Willis MkII High Speed Pantograph. Please see image below taken from the 2014 line of route for the class. I worked on these units whilst they operated on TL.

 

[fgwrich]

Just a correction here. Whilst it was initially suggested the pantographs would be changed for the same type that was already operating on the GN, this did not happen, instead the existing pantographs were validated with the ECML wiring. The only 387’s that had their pantographs ‘downgraded’ were the ones supplied to c2c, and as far as I am aware had to have their top speed reduced to reflect this. Happy to be corrected if the c2c units can run at 110, but all the /1s and /2s have the same pantograph type as new.

There is a small difference in Pantograph designs, I can't link to the post directly but, as explained by @FGW_DID in post 201 in this thread regarding the hire in of the C2C units to GWR (since transferred). GWR's units can run at 110.

The C2C 387s have HSP MK1 heads fitted, GWR have HSP MK2 heads fitted so the MK2 are being fitted. (Don’t know the technicalities behind it)
Also the Pantograph over height settings will need adjusting to accommodate the higher OLE over the level crossing at Newbury.

Speculation on alternative traction covering the grounding of Class 80x fleet

Reported elsewhere that the c2c sets need a software update (at least the PIS would need altering) and pantograph heads changing. Why would the pantograph heads need changing?

www.railforums.co.uk

 

[Magdalia]

The two photos show the same pantograph. I appreciate that with the photo from the MML, the pantograph is hard to see, but if you look closely you can see the arc horns on both images. the pantograph on the units has always been a Brecknell Willis MkII High Speed Pantograph. Please see image below taken from the 2014 line of route for the class. I worked on these units whilst they operated on TL.
View attachment 111120

Thanks, in this case a diagram is better than a picture. I tried to find a better picture of 387104 on the MML but nearly all the pictures were south of the river with the pantograph lowered!

But the class 387s used on the GN driver training trips 387104/114/120 definitely all had new pantographs, even if they were the same design.

I take it that "arc horns" is the professional's name for what I called the "bobbly bits"? Are they always the same, or can they be changed? Would different size/weight affect the amount of pressure that the pantograph applies to the contact wire?

 

[brad465]

Something that doesn't seem to have been mentioned (apologies if I've missed it if it has), did gearing need to be considered in upgrading the 360s? The 458s were re-geared when their top speed was lowered from 100 to 75mph, and I presume this will have to be reversed for their next refurbishment.

 

[507020]

Something that doesn't seem to have been mentioned (apologies if I've missed it if it has), did gearing need to be considered in upgrading the 360s? The 458s were re-geared when their top speed was lowered from 100 to 75mph, and I presume this will have to be reversed for their next refurbishment.

Despite what the TOPS numbering may suggest, 450s, 350s and 360s are all identical trains, with the last few completed 450s designated 350s and given pantographs and the some completed 350s losing their gangways and being designated 360s, with 444s and 380s not much different. Whatever was done with the 360s was something already proven with the 350s. What was done with the 458/5s was something else entirely and I don’t understand why it should be reversed.

 

[edwin_m]

Something that doesn't seem to have been mentioned (apologies if I've missed it if it has), did gearing need to be considered in upgrading the 360s? The 458s were re-geared when their top speed was lowered from 100 to 75mph, and I presume this will have to be reversed for their next refurbishment.

Don't know the answer to that, but previous comments indicate that the 360 motors were re-designed to turn faster, which suggests the extra speed was achieved that way rather than by re-gearing. I read that the 458 re-gearing was related to cooling - something to do with the fans being directly driven off the motors and not turning fast enough at 75mph with the original gearing to keep the motors cool. That suggests they may have a problem if the units are made capable of 100mph again, but are normally run at lower speeds.

Despite what the TOPS numbering may suggest, 450s, 350s and 360s are all identical trains, with the last few completed 450s designated 350s and given pantographs and the some completed 350s losing their gangways and being designated 360s, with 444s and 380s not much different. Whatever was done with the 360s was something already proven with the 350s. What was done with the 458/5s was something else entirely and I don’t understand why it should be reversed.

Indeed, I was involved in producing the safety case for these units and they were all identical in almost all respects, bar the inclusion or not of various "optional" components like gangways and shoegear. The 458 issue is because they are currently used on duties where 75mph is sufficient, but SWR wants to re-deploy them where they need to run at 100mph.

 

[507020]

The 458 issue is because they are currently used on duties where 75mph is sufficient, but SWR wants to re-deploy them where they need to run at 100mph.

I thought it was the other way round, that when new they were designed for 75mph and regeared to 100mph when lengthened to 5 cars, but that SWR now wants to revert this.

 

[aleggatta]

Thanks, in this case a diagram is better than a picture. I tried to find a better picture of 387104 on the MML but nearly all the pictures were south of the river with the pantograph lowered!

But the class 387s used on the GN driver training trips 387104/114/120 definitely all had new pantographs, even if they were the same design.

I take it that "arc horns" is the professional's name for what I called the "bobbly bits"? Are they always the same, or can they be changed? Would different size/weight affect the amount of pressure that the pantograph applies to the contact wire?

I wouldn't like to say for sure if they had new pantographs fitted, knowing how well they clean up with the right products (and how anal we were about them because we weren't an AC depot, and didn't want the blame for any issues!), but it wouldn't surprise me if they had transferred after having routine maintenance. It might be that they had new carbons fitted just to see how they wore on the new route. The 387's were on their way over when I was still working with them, so a standard part of mileage based exams for these units were to have the pantographs cleaned, and more intense mileage based exams had full inspection also. Part of the winterisation programme was to also clean everything down on the pantograph and apply a de-icing product, basically turning every pan exam in winter into a full pan clean and inspect (which would normally only be done on major M exams (M4-6)) depending on how you interpreted the winterisation brief for that year.

The arc horns are the bobbly bits you refer to! They are designed to be a point that an arc can be generated from if something gets too close to the pan, giving some protection to the carbons themselves to prevent a unit being stranded. They cannot be changed out, and (AFAIK) if there is an issue with them, the whole pantograph has to be changed (from the insulators up). The arc horns are a fixed weight and size, all linked to the aerodynamics of the pan, and the upwards pressure of the pantograph is controlled by a pressure regulator that controls how much air is in the raising cylinder.

It's worth noting, that now the 387 fleets are effectively operated on single voltage lines only, the pan exam for DC units has become a time based exam item, with the shoegear on AC units being a time based exam item.

I hope you can appreciate, with my experience of the units the only reason a pan would be changed is from it being destroyed from hitting something/bringing the knitting down. I've made them look like new in the past so wouldn't blame you for believing they were replaced! They certainly are built well!

 

[43096]

I thought it was the other way round, that when new they were designed for 75mph and regeared to 100mph when lengthened to 5 cars, but that SWR now wants to revert this.

That's incorrect. They were built as 100mph units (basically VEP replacements) and the 458/5 conversion for more "metro" duties only needs 75mph max. They were re-geared to reflect the duty and the over-heating issue as above which was picked up in the modelling before they were converted. In short, the stop-start duty cycle means the motors are worked harder so if they were 100mph geared the motors would be spinning more slowly at any given train speed, which would draw less air in. By re-gearing to 75mph the motor spins faster so draws more air in and keeps the motor cool. (As an aside the Class 460 conversions would have needed re-gearing anyway as they had 125mph gearing which was optimal for the Gatwick Express duty, even though they were 100mph units). There was a lengthy feature on the 458/5 project in Modern Railways by Ian Walmsley - and he should know as it was his project when he was at Porterbrook.

The requirement for the 458s for their new duties is longer distance 90/100mph services predominantly on the Portsmouth Direct, so they will need re-gearing back to 100mph and have their yaw dampers re-fitted.

 

[cjmillsnun]

I thought it was the other way round, that when new they were designed for 75mph and regeared to 100mph when lengthened to 5 cars, but that SWR now wants to revert this.

SWR would definitely want 100MPH gearing on express services. Much of it is 80+ MPH line speed.

 

[507020]

That's incorrect. They were built as 100mph units (basically VEP replacements) and the 458/5 conversion for more "metro" duties only needs 75mph max. They were re-geared to reflect the duty and the over-heating issue as above which was picked up in the modelling before they were converted. In short, the stop-start duty cycle means the motors are worked harder so if they were 100mph geared the motors would be spinning more slowly at any given train speed, which would draw less air in. By re-gearing to 75mph the motor spins faster so draws more air in and keeps the motor cool. (As an aside the Class 460 conversions would have needed re-gearing anyway as they had 125mph gearing which was optimal for the Gatwick Express duty, even though they were 100mph units). There was a lengthy feature on the 458/5 project in Modern Railways by Ian Walmsley - and he should know as it was his project when he was at Porterbrook.

The requirement for the 458s for their new duties is longer distance 90/100mph services predominantly on the Portsmouth Direct, so they will need re-gearing back to 100mph and have their yaw dampers re-fitted.

Thank you for the detailed explanation. I was aware the post-Covid intention was to run them on the Portsmouth Direct instead of the planned 442s, but didn’t realise about the 460s or yaw dampers. Did the 460s have the same motors as 458s but with different gearing and was 125mph gearing more appropriate for sustained 100mph running on Gatwick Express? What was the need for the yaw dampers to be removed? I have been told that they are required above 75mph but why not retain them?

 

[Starmill]

The only place where 700s could run above 100mph is for a few miles between Finsbury Park and Woolmer Green (where they switch to the slow lines). Someone else will know but 125mph doesn't start until north of Woolmer Green. The time saving would be a few seconds at most.

There would have been a handful of places on the fast lines on the MML too, but mainly only affecting the roughly 6 trains per day using them between Bedford and Luton, and still saving mere seconds, just as you say.

 

[43096]

Did the 460s have the same motors as 458s but with different gearing and was 125mph gearing more appropriate for sustained 100mph running on Gatwick Express?

Same type of motors, I believe.

What was the need for the yaw dampers to be removed? I have been told that they are required above 75mph but why not retain them?

The yaw dampers aren’t needed for 75mph maximum, so were taken off. It’s a maintenance saving as they won’t need maintenance or overhaul. At the time the 458s were expected to remain as 75mph units for the rest of their lives.

 

[swt_passenger]

Something that doesn't seem to have been mentioned (apologies if I've missed it if it has), did gearing need to be considered in upgrading the 360s?

No, it was definitely done on 350s just by strengthening of the rotors. The explanation of exactly what was needed is in the track access application for the LM Trent Valley services.