Fastest Accelerating MUs in the UK

[Bletchleyite]

Maybe not so, the motors will only use sufficient energy to maintain the speed that the driver requires.
However if the gearing is unusually high then it may not be as efficient as a motor geared for the local line speeds.

With electrics it is I think more the case that you'll get poor acceleration if it's geared for a high speed and you don't use it as such, and less that energy usage would be an issue.

 

[Mikey C]

With electrics it is I think more the case that you'll get poor acceleration if it's geared for a high speed and you don't use it as such, and less that energy usage would be an issue.

Which is why it's really weird to gear the 460s for 125mph, instead of 100mph like the other stock operating on the Brighton Main Line

 

[AM9]

Maybe not so, the motors will only use sufficient energy to maintain the speed that the driver requires.
However if the gearing is unusually high then it may not be as efficient as a motor geared for the local line speeds.

You could same about a car, I own a VW Golf that is limited (by VW) to a maximum speed of 155 mph, but returns reasonable fuel consumption at UK legal speeds. If I wanted better economy then a similar car with a smaller / less powerful engine would be a sensible option. FWIW, 0-60 mph can be attained in 5 seconds, 0-100 takes 12 seconds. (Figures from an Autocar road test, not personal experience....)

I wasn't thinking of cruising, especially as the intended VIC-GTW route doesn't have much scope for that. Their acceleration should be matched to the maximum speed expected in service otherwise additional energy would be spent taking them up to linespeed because they would be accelerating for more of the time. That also has an impact on headways and journey times wherever they are used on the 3rd rail network with no linespeed greater than 100mph.
I assume that they didn't have regen but if they did, it would be far less efficient, with output dropping to unusable levels well before the train stopped.
Your car analagy is inappropriate because an overpowered car has better acceleration (with the use opf gears) up to the road equivalent of linespeed, thus it can then be shifted into top/overdrive to cruise. EMUs have fixed gear ratios (as in motor rotation speed vs linear speed on the track), so the power that the motors consume is wasted in terms of the higher speeds never being attained yet their torque for efficient starting is reduced bacause of the high gearing. I can't understand why BR introduced a class of trains that were so poorly matched to their intended service role. It's not as if EMU technology was novel in the late '90s.

 

[rebmcr]

I wasn't thinking of cruising, especially as the intended VIC-GTW route doesn't have much scope for that. Their acceleration should be matched to the maximum speed expected in service otherwise additional energy would be spent taking them up to linespeed because they would be accelerating for more of the time. That also has an impact on headways and journey times wherever they are used on the 3rd rail network with no linespeed greater than 100mph.
I assume that they didn't have regen but if they did, it would be far less efficient, with output dropping to unusable levels well before the train stopped.
Your car analagy is inappropriate because an overpowered car has better acceleration (with the use opf gears) up to the road equivalent of linespeed, thus it can then be shifted into top/overdrive to cruise. EMUs have fixed gear ratios (as in motor rotation speed vs linear speed on the track), so the power that the motors consume is wasted in terms of the higher speeds never being attained yet their torque for efficient starting is reduced bacause of the high gearing. I can't understand why BR introduced a class of trains that were so poorly matched to their intended service role. It's not as if EMU technology was novel in the late '90s.

That's not how thermodynamics works.

 

[delticdave]

With electrics it is I think more the case that you'll get poor acceleration if it's geared for a high speed and you don't use it as such, and less that energy usage would be an issue.

Agreed. So, is there a case for a constant speed electric motor driving the wheels through a CVT?

 

[Railperf]

I'm not thinking total change of a gearset that's in use- what I mean is, the Stadler trains have been developed for 100mph running here in the UK, and will have been developed from the ground up for those requirements, would it not make sense to fit the 'correct' ratios? Changing the size of the gears won't cost much when it's designed from the start. After all, there are a number of trains that have been re-geared partway through their lives.

In the same way, changing the gearbox on an already built bicycle costs money. Building a bicycle and deciding on a different set of gears doesn't cost- you were going to buy gears anyway, you've just made a different decision on which ones to chose.

Train manufacturers tend to buy 'off the shelf' electric motors and adapt it to their product. Whereas gearboxes are most likely specific to the train / bogies / wheelset and therefore made to order. If you have a product range that encompasses maximum speeds between 75mph and 125mph, -it must be far cheaper to use a standard gearbox, and choose the right motors to suit the application.
Drivers have commented that both 755/4 and 755/4 acceleration is clearly artificially limited by the traction software and appear to be able to run at much higher speeds. Lowering the gear ratio's from say 125mph maximum service speed to 100mph service speed is not necessary. neither do i believe it would make a huge improvement to the acceleration to justify the huge cost to buy and install new gearboxes.

Lowering the gear ratios from a 125mph unit to 75mph is a different story and probably more worthwhile if the train is fitted with older style DC motors - where performance decreases the faster they spin!

 

[hexagon789]

Train manufacturers tend to buy 'off the shelf' electric motors and adapt it to their product. Whereas gearboxes are most likely specific to the train / bogies / wheelset and therefore made to order. If you have a product range that encompasses maximum speeds between 75mph and 125mph, -it must be far cheaper to use a standard gearbox, and choose the right motors to suit the application.
Drivers have commented that both 755/4 and 755/4 acceleration is clearly artificially limited by the traction software and appear to be able to run at much higher speeds. Lowering the gear ratio's from say 125mph maximum service speed to 100mph service speed is not necessary. neither do i believe it would make a huge improvement to the acceleration to justify the huge cost to buy and install new gearboxes.

Lowering the gear ratios from a 125mph unit to 75mph is a different story and probably more worthwhile if the train is fitted with older style DC motors - where performance decreases the faster they spin!

Given the 200km/h FLIRTS seem outwardly identical to the 160km/h ones, I think it's very probable it's simply an electronic limiter that creates the nominal maxima

 

[gingertom]

Given the 200km/h FLIRTS seem outwardly identical to the 160km/h ones, I think it's very probable it's simply an electronic limiter that creates the nominal maxima

that plus having more powered bogies. If in doubt, throw more horsepower at it.

 

[Railperf]

I'm in the fortunate position of driving and instructing on both forms of traction, over the same stretches of track, and if I was in a drag race between the two, i'd be choosing the 180.

First days of these in public service and they are not sparkling. 180111 is on 5 engines but struggling through the speed range. Assuming 180110 is on 1B31 then that is struggling too as it is losing time all the way back from Corby.
From Luton Airport Parkway 180111 slower than the Angel 2+6 HST set!!
Loughborough Northbound 0 to 60mph in 82s and 100mph in 222s. The 180s are a pile of junk!!

 

[hexagon789]

that plus having more powered bogies. If in doubt, throw more horsepower at it.

Right enough, I'd forgotten the 200km/h Norwegian ones have an extra motored bogie, though afaik the Leo Express ones don't and they have a 189km/h design speed but only run at 160 in service.

 

[Railperf]

Yes the NSB type 75 are a five car unit with three motor bogies. To be fair.. I don't recall it accelerating much faster than a Class 745. The additional power is used to attain and maintain the higher top speed. I get the feeling that acceleration is 'tuned' to meet NSB specifications. I recall a driver telling me it had been toned down because people were falling over when full power was applied.

 

[Kneedown]

First days of these in public service and they are not sparkling. 180111 is on 5 engines but struggling through the speed range. Assuming 180110 is on 1B31 then that is struggling too as it is losing time all the way back from Corby.
From Luton Airport Parkway 180111 slower than the Angel 2+6 HST set!!
Loughborough Northbound 0 to 60mph in 82s and 100mph in 222s. The 180s are a pile of junk!!

Give them time. They've been stood idle all Summer. Need to blow the cobwebs out and bed in for consistent performance. Drivers need to gain confidence too. Many haven't touched one since training.

 

[Railperf]

Give them time. They've been stood idle all Summer. Need to blow the cobwebs out and bed in for consistent performance. Drivers need to gain confidence too. Many haven't touched one since training.

You must be one of the few people so positive about these I have travelled extensively on them aboard GC FGW and HT services and find the overall reliability appalling compared to the 222's and as a result the acceleration and speeds attained are often way below standard. Let me know once you feel the 'cobwebs have been blown out' and I will come out and see how they are performing.

 

[Kneedown]

You must be one of the few people so positive about these I have travelled extensively on them aboard GC FGW and HT services and find the overall reliability appalling compared to the 222's and as a result the acceleration and speeds attained are often way below standard. Let me know once you feel the 'cobwebs have been blown out' and I will come out and see how they are performing.

I remember when the HST's were first introduced to the MML. They used to go "Pop" left, right and centre for a good few years. I didn't complain though, kept my beloved 45's going for a bit longer.
A lot of people forget that HT are a small outfit relying solely on revenue. With the small fleet they had, downtime for maintenence and tlc was limited. EMR have had to do a lot of work just to bring them up to an acceptable standard after years of neglect. Hopefully we'll spend a bit more, but that remains to be seen.

 

[Railperf]

I remember when the HST's were first introduced to the MML. They used to go "Pop" left, right and centre for a good few years. I didn't complain though, kept my beloved 45's going for a bit longer.
A lot of people forget that HT are a small outfit relying solely on revenue. With the small fleet they had, downtime for maintenence and tlc was limited. EMR have had to do a lot of work just to bring them up to an acceptable standard after years of neglect. Hopefully we'll spend a bit more, but that remains to be seen.

Let's hope so. Would like to see what these can do when they are in a healthy mechanical state!!

EMR have had to do a lot of work just to bring them up to an acceptable standard after years of neglect. Hopefully we'll spend a bit more, but that remains to be seen.

EMR will need to in order to achieve right time running. Both units today were losing time. 180111 lost traction power from Wellingborough southbound..though the engine remained idling. Breasted Sharnbrook summit at a paltry 70mph. For the time being I am yet to be convinced they are superior to a 222.

 

[AM9]

Train manufacturers tend to buy 'off the shelf' electric motors and adapt it to their product. Whereas gearboxes are most likely specific to the train / bogies / wheelset and therefore made to order. If you have a product range that encompasses maximum speeds between 75mph and 125mph, -it must be far cheaper to use a standard gearbox, and choose the right motors to suit the application.
Drivers have commented that both 755/4 and 755/4 acceleration is clearly artificially limited by the traction software and appear to be able to run at much higher speeds. Lowering the gear ratio's from say 125mph maximum service speed to 100mph service speed is not necessary. neither do i believe it would make a huge improvement to the acceleration to justify the huge cost to buy and install new gearboxes.

Lowering the gear ratios from a 125mph unit to 75mph is a different story and probably more worthwhile if the train is fitted with older style DC motors - where performance decreases the faster they spin!

The 3-car class 755 has a power to weight ratio on electric mode of 22.7kW/tonne (30.5bhp/tonne). That is way above any other UK EMU* and therefore it's no surprise that their acceleration is currently the highest. With such power on board, there is no problem in limiting the power of the motors to match the performance to the route. The situation is completely different on normal EMUs where transformers and traction equipment must be distributed underfloor to avoid sacrificing capacity. Thus there is a trade-off between acceleration and maximum speed. Axle mounted traction motors are pretty 'off-the-shelf' as you say, the Southern and BR(SR) EMUs used the same 1935 designed EE507 250HP motors into the 80s until series wound motors were superceded by ac induction types. There were also GEC equivalents (some with power outputs over 300HP) that were used in many BR EMU design/manufacture of course) to give a different linear travel per motor revolution.

* A4-car 4-REP without any 4TC units only has a power to weight ratio of 13.7 and doesn't run alone in service anyway. Even some light Locos don't have a power to weight ratio as high as the class 755/3 units, - e.g. a class 73/1 has only about 15.3kW/tonne.

 

[hexagon789]

Yes the NSB type 75 are a five car unit with three motor bogies. To be fair.. I don't recall it accelerating much faster than a Class 745. The additional power is used to attain and maintain the higher top speed. I get the feeling that acceleration is 'tuned' to meet NSB specifications. I recall a driver telling me it had been toned down because people were falling over when full power was applied.

No disrespect to Norwegian railways, but do they have much opportunity to run at 200km/h? I believe the airport line is 210, but is any of the general Norwegian regional/InterCity network?

 

[Kneedown]

Let's hope so. Would like to see what these can do when they are in a healthy mechanical state!!


EMR will need to in order to achieve right time running. Both units today were losing time. 180111 lost traction power from Wellingborough southbound..though the engine remained idling. Breasted Sharnbrook summit at a paltry 70mph. For the time being I am yet to be convinced they are superior to a 222.

They'll not be out today. 110's battery charge fault has manifested itself again. Failed on Etches.
My last trip over Sharnbrook with 111 and 109 had me easing off the power well before I've ever had to with a 222.

 

[Railperf]

They'll not be out today. 110's battery charge fault has manifested itself again. Failed on Etches.
My last trip over Sharnbrook with 111 and 109 had me easing off the power well before I've ever had to with a 222.

Actually the speed over Sharnbrook from Wellingboro was worse than i thought - just 58mph according to the datalogger. Weren't your favourite Class 45's faster?

Be interesting to note what the driver reported. From a passenger perspective, traction power clearly in use until Wellingborough. From Wellingborough southbound the train started with engine in coach B idling only. Then i would say it seemed that the acceleration paused, and then it sounded like engines in coach B revved up to full power, but crucially quieter than usual and no gearchanges at the 68mph and 98mph mark as usual. So if the driver had noted the sluggish acceleration and tried to re-engage the traction power, it hadn't worked. From Bedford the power seemed to be restored - but I had left the train at that point.

 

[Kneedown]

Actually the speed over Sharnbrook from Wellingboro was worse than i thought - just 58mph according to the datalogger. Weren't your favourite Class 45's faster?

Be interesting to note what the driver reported. From a passenger perspective, traction power clearly in use until Wellingborough. From Wellingborough southbound the train started with engine in coach B idling only. Then i would say it seemed that the acceleration paused, and then it sounded like engines in coach B revved up to full power, but crucially quieter than usual and no gearchanges at the 68mph and 98mph mark as usual. So if the driver had noted the sluggish acceleration and tried to re-engage the traction power, it hadn't worked. From Bedford the power seemed to be restored - but I had left the train at that point.

Had a chat with the Driver earlier. Two transmissions out on 50911 and 54911. Transmissions still out this morning so it'll be a slow run again. Can hardly compare that to a 222 on 5, or even 4 engines. It'll be reet when it's fixed. 110 is playing nicely today.

 

[hexagon789]

110 is playing nicely today.

Shhh, don't jinx it!

In all seriousness I'm sure we all want for the 180 fleet to get to a reasonable level of reliability soon, but how readily that will come...

They are supposed to be fairly decent at shifting though when all's well and good

 

[Railperf]

Had a chat with the Driver earlier. Two transmissions out on 50911 and 54911. Transmissions still out this morning so it'll be a slow run again. Can hardly compare that to a 222 on 5, or even 4 engines. It'll be reet when it's fixed. 110 is playing nicely today.

I can only record the performance available. Lol. If the 180's are going to be frequently running on engines out and transmissions not engaging..then that will reflect their overall performance. In contrast, the 222's - not immune to losing an engine / GU - usually seem to be doing what we expect of them.
The 222's are detuned and we know their performance is not what was available from new - but they seem to be reasonably reliable.

I'm sure the 180's with a further 250bhp available per set could be quicker. I just haven't seen that yet on seemingly 'healthy' units. But 50% of the time or more there always seems to have been an issue that has caused a reduction of performance.

Great to have a set working 100% at the start of the day - but how useful is that if after a few hours it all starts going wrong?
Out of interest, what is the issue with the transmissions and how do you as drivers assess what's going on and remedy that on the move or at station stops?

UPDATE 11:11am Looking at both diagrams this morning post St Pancras split. The 0735 St Pancras to Nottingham service losing time there and back - so assuming that's 111. And the 0745 St Pancras to Corby unit had a good run out, but has lost time on the return - so struggling to pick up the lost time. Not sure if that indicates an issue?

I'm in agreement with @hexagon789 above. I really want to see these units do well and experience the promise that's so far not been realised through the 180's life except in patches. Some of the fastest GWR point to point times have been achieved with 180's prior to Class 800 on electric arriving.

Would like to see the 180's turn out the sort of performances that are going to give the Hitachi bi-modes something to aim for.

So far - neither a 222 or a 180 hold's a candle to the 755/4 BMU in diesel mode, though i do believe the 222's -pre detune- were capable of a faster 0-100mph time!

 

[hexagon789]

I'm in agreement with @hexagon789 above. I really want to see these units do well and experience the promise that's so far not been realised through the 180's life except in patches. Some of the fastest GWR point to point times have been achieved with 180's prior to Class 800 on electric arriving.

Would like to see the 180's turn out the sort of performances that are going to give the Hitachi bi-modes something to aim for.

So far - neither a 222 or a 180 hold's a candle to the 755/4 BMU in diesel mode, though i do believe the 222's -pre detune- were capable of a faster 0-100mph time!

Only a vague recollection but I asked someone familiar with them from FGW times and he reckoned that a healthy 180 could manage 125mph in about 5 mins if the driver doesn't hang about.

A rough recollection but perhaps that can be compared to the 222 figure?

 

[Kneedown]

I've just spent four night shifts at Etches, overseeing the units allocated to the two diagrams, trying to make sure all was well and that the units were ok to enter service. I'm still new to the traction, as are Etches Park fitters and Maintenance Controllers. We're all still learning about them. We do have one former HT who has joined us, and is an oracle of knowledge about them, but he can't be around 24/7 for advice. We do the best we can, but we still have much to learn. I had a possible answer to the transmission problem today though, and we need to get that briefed out to Staff.
HT ran the units intensively with a bare minimum maintenance. I hope that, with a larger fleet, we will be able to look after them a bit more intensively. I would personally like to see the introduction to service delayed to enable all snags and recurring faults to be addressed fully, or at least cut it to one diagram daily which would leave one stand by by unit, and one in the shed for remedial work, at least until 109 returns from Crofton. As it currently stands there are two diagrams, with one stand by unit, which leaves little room for manoeuvre.

 

[hexagon789]

I've just spent four night shifts at Etches, overseeing the units allocated to the two diagrams, trying to make sure all was well and that the units were ok to enter service. I'm still new to the traction, as are Etches Park fitters and Maintenance Controllers. We're all still learning about them. We do have one former HT who has joined us, and is an oracle of knowledge about them, but he can't be around 24/7 for advice. We do the best we can, but we still have much to learn. I had a possible answer to the transmission problem today though, and we need to get that briefed out to Staff.
HT ran the units intensively with a bare minimum maintenance. I hope that, with a larger fleet, we will be able to look after them a bit more intensively. I would personally like to see the introduction to service delayed to enable all snags and recurring faults to be addressed fully, or at least cut it to one diagram daily which would leave one stand by by unit, and one in the shed for remedial work, at least until 109 returns from Crofton. As it currently stands there are two diagrams, with one stand by unit, which leaves little room for manoeuvre.

An unfortunate situation, any word on how long before '109 might return to ease it?

 

[Kneedown]

An unfortunate situation, any word on how long before '109 might return to ease it?

Not heard when it'll be back i'm afraid. I'm not even sure what it's up there for. I do know an engine on one set was isolated as it was on max hours before exam. Might be that one.

 

[Railperf]

So which other unit is the 'spare' if 110 and 111 are the two in service?

 

[hexagon789]

Not heard when it'll be back i'm afraid. I'm not even sure what it's up there for. I do know an engine on one set was isolated as it was on max hours before exam. Might be that one.

Thanks anyway, in an ideal world it'll be back before long!

So which other unit is the 'spare' if 110 and 111 are the two in service?

113?

 

[Railperf]

Thanks anyway, in an ideal world it'll be back before long!


113?

If 113 is serviceable, why did it not replace 111 with two dodgy transmissions?

 

[hexagon789]

If 113 is serviceable, why did it not replace 111 with two dodgy transmissions?

No idea, but 113 is the only other unit EMR has so what else could it be?