Northern rolling stock changes post electrification

[notadriver]

Maybe they could raise the 323s top speed to 100 mph as part of their retractioning. They are much quicker than 319s off the mark.

 

[Nym]

Since when are 323s being re-tractioned?

 

[furnessvale]

Maybe they could raise the 323s top speed to 100 mph as part of their retractioning. They are much quicker than 319s off the mark.

Would they still be quicker off the mark if geared up for 100mph?

 

[notadriver]

Since when are 323s being re-tractioned?

I read somewhere they are swapping out the GTO equipment for modern IGBTs.
--- old post above --- --- new post below ---

Would they still be quicker off the mark if geared up for 100mph?

I believe they would be. The 317s were originally 90 mph units. This was increased to 100 with no changes in actual gear ratio afaik.

 

[Nym]

I read somewhere they are swapping out the GTO equipment for modern IGBTs.

When I was speaking to a rather senior guy at Porterbrook, he was saying about how they're the first set they won't be retractioning, unless the TOCs desperately want regenerative braking. As the GTOs are pretty reliable and they already use AC traction motors.

 

[childwallblues]

The Warrington Bank Quay services will still be DMU's until December.

And there will be one or two working that a DMU vice Electric (balancing moves) 1739 Lime St-Man Vic off the top of my head will be one and 1903 Wigan-Lime St because there's no 319 into Wigan, it comes off the 1814 Man Vic-Wigan

The 1903 is booked for 2 x 142 and departs from Platform 2 at WGN.

 

[northwichcat]

Since when are 323s being re-tractioned?

It's been reported that one of the Northern ones is out-of-service for retractioning. I'm not aware of any proposed changes to top speed though.

 

[158722]

It's been reported that one of the Northern ones is out-of-service for retractioning. I'm not aware of any proposed changes to top speed though.

Is this the reason behind reports that the Airport shuttle will go over to a 319 vice 323? Apologies if I've missed this at some point!

Northern still awaiting 4 319s from Wolverton (366/377-379) - are these not going to be missed when the Liverpool-Prestons (nee Blackpools) go electric?

 

[northwichcat]

Is this the reason behind reports that the Airport shuttle will go over to a 319 vice 323? Apologies if I've missed this at some point!

I asked about that when it was first posted and no-one seems able to answer that query.

There is still a 4 car DMU working between Macclesfield and Manchester in the morning switch which could easily switch to a 323. As long as alternative units are found for the FO Stockport-Stalybridge, which I can't see being an issue.

Alternatively the Crewe-Bolton service could be split to allow a 323 to be used with the 06:58 Chester-Piccadilly extended to Bolton in lieu - as long as one of the released DMUs is used to strengthen the 06:58 Chester-Piccadilly.

Although there's nothing AFAIK which can easily switch in the evening peak. The 16:58 Piccadilly-Hazel Grove is part of the same diagram as the 17:58 Stockport-Chester so switching that service may just result in a DMU sat at Newton Heath for longer. While the 17:23 Piccadilly-Hazel Grove currently continues to Chinley.

 

[childwallblues]

319377 was due at Allerton MPD from Wolverton Works tonight.

 

[Bevan Price]

Would they still be quicker off the mark if geared up for 100mph?

323s are already capable of reaching (at least) the mid to high 90s - but presumably to minimise maintenance costs, management has set a 90 mph limit. Before radar traps & data recorders became widespread, I have been on 323s that reached 94 - 95 mph.

 

[samj]

So do the 319s begin their Preston-Liverpool work tomorrow as scheduled?

 

[61653 HTAFC]

323s are already capable of reaching (at least) the mid to high 90s - but presumably to minimise maintenance costs, management has set a 90 mph limit. Before radar traps & data recorders became widespread, I have been on 323s that reached 94 - 95 mph.

As units certified for 90mph running they'll have reached at least 99mph on test (maximum permitted +10%).

 

[Loop & Link]

So do the 319s begin their Preston-Liverpool work tomorrow as scheduled?

Yep, there was a 5T99 balancing move this morning to get a 319 in the right place at Preston.

 

[AM9]

323s are already capable of reaching (at least) the mid to high 90s - but presumably to minimise maintenance costs, management has set a 90 mph limit. Before radar traps & data recorders became widespread, I have been on 323s that reached 94 - 95 mph.

That doesn't answer the question. If their gearing is modified to reach a maximum of 100mph in service, (and the motors themselves are unmodified) then the power available will reduce the available acceleration perfromance to a degree. They will also (theoretically) be able to reach 110mph under test as an absolute maximum speed, (max. service speed plus 10%).

 

[notadriver]

I think the affect on acceleration will between a 90 mph and 100 mph geared unit is negligible. 75 mph gearing however is a different matter. 376s and 458/5s were given this gearing to improve acceleration where their sisters (375 and 458/0) were still rated at 100 mph.

According to a railway magazine a 357 holds the 0-60 record.

 

[furnessvale]

I think the affect on acceleration will between a 90 mph and 100 mph geared unit is negligible. 75 mph gearing however is a different matter. 376s and 458/5s were given this gearing to improve acceleration where their sisters (375 and 458/0) were still rated at 100 mph.

Negligible it may be, but it must still be there or all units would be geared for 100 rather than 90 to increase flexibility.

It will take a specialist engineer to quantify the difference and calculate the effect on a late running multi stop 100mph unit struggling to make up time, or, to be fair, the effect of attempting to run a faster service with a 90mph unit.

 

[notadriver]

There are a lot more factors than just that. For example my toc used 75 mph networkers which surprisingly can keep time on a route which has 90 mph line speeds and stock capable of 100 mph.

On Southern they have the 377/6 units did/doing predominantly suburban work but geared for 100 mph and not 75 mph as one might expect.

 

[furnessvale]

There are a lot more factors than just that. For example my toc used 75 mph networkers which surprisingly can keep time on a route which has 90 mph line speeds and stock capable of 100 mph.

On Southern they have the 377/6 units did/doing predominantly suburban work but geared for 100 mph and not 75 mph as one might expect.

Exactly why I said it takes a specialist engineer.

On a perfectly balanced system, what a 75mph unit makes up in better acceleration, a 100mph unit makes up in higher top speed to arrive at the destination at exactly the same time.

 

[notadriver]

If you're saying that then there is no advantage in having a unit geared for the higher speed.

With respect I know what you are saying about specialist engineers but surely real world experience of what actually happens is more applicable ?

 

[furnessvale]

If you're saying that then there is no advantage in having a unit geared for the higher speed.

With respect I know what you are saying about specialist engineers but surely real world experience of what actually happens is more applicable ?

No, I said a perfectly balanced system.

To mention just one factor. Closer spaced stations than perfection would give the 75mph unit the edge. Wider spacing would favour the 100mph unit.

Any engineer worth his salt would incorporate real world experience into his calculations, but the idea that Alsthom, for example, would build a new unit and then hand it over to drivers to "see what she will do" as a basis for design is a non starter.

 

[notadriver]

No- one is suggesting that engineers would do that. I'm simply telling you what happens in the real world as the perfectly balanced system doesn't exist except on a computer.

Drivers are now getting involved when the cab is designed however.

I would suggest the 90 mph top speed derives from the fact they were designed for the Birmingham Cross City route that has a 90 mph Max line speed.

 

[furnessvale]

No- one is suggesting that engineers would do that. I'm simply telling you what happens in the real world as the perfectly balanced system doesn't exist except on a computer.

Drivers are now getting involved when the cab is designed however.

I would suggest the 90 mph top speed derives from the fact they were designed for the Birmingham Cross City route that has a 90 mph Max line speed.

We seem to have wandered off track a bit. I simply effectively asked if a unit regeared from 90 to 100 would still be able to accelerate at the same rate or at least maintain its superiority over a different 100mph unit.

Only one poster has suggested that acceleration at the same rate is impossible, which I agree with.

No one has produced any evidence that it could still maintain its superiority except for anecdotal statements.

Given some slackness in timetabling they probably will keep to time, but that is a far cry from a regeared unit maintaining acceleration rates, or the use of overspeeding to magically convert a 90mph unit into a 100mph one.

 

[notadriver]

Well can we use some examples ? Do you think a 90 mph geared 323 quicker to accelerate than a 100 mph geared EMU like a 360 etc ?

 

[87015]

Well can we use some examples ? Do you think a 90 mph geared 323 quicker to accelerate than a 100 mph geared EMU like a 360 etc ?

321s kept to 323 timings on the Walsalls...

 

[158722]

So how many of the 17 319s delivered to Allerton are diagrammed? Essentially?
3 on Liverpool-Manchester Airport?
4 on Liverpool-Wigan?
3 on Liverpool-Manchester Victoria?
3 on Liverpool-Preston?

13 from 16 (given 319377 has only been delivered)

Give two are expected on the Liverpool-Warringtons from December and another on the Manchester Airport shuttle (from when?), that would suggest still only 16 from 20 diagrammed. Hot stand-by diagrammed too?

 

[AM9]

Well can we use some examples ? Do you think a 90 mph geared 323 quicker to accelerate than a 100 mph geared EMU like a 360 etc ?

Just to exit from this off-topic diversion as it seems that my assertion is causing some disagreement, (although this isn't my branch of electrical engineering):

The acceleration of an EMU assuming full adhesion, is dependant on three things:
1) the power to weight ratio of the unit, (i.e. HP/tonne)
2) the power/torque curve of the traction package*
3) the ratio of motor speed vs wheel speed, i.e. the gear ratio.
As the question posed was regarding just a change in the gearing (as in 3) above), then item 1) can be ignored, item 2) I assume could be left as is and three will have a linear effect on the acceleration except there will be a minor additional loss owing to air resistance at higher speeds.
It just isn't possible for a '100mph' gearing to accelerate as fast as a lower '90mph' setup if the prime drive is the same. As somebody said, 'ye canna change the laws of physics', there's only so much power there.
* If the line characteristics require specific acceleration curves, there may be opportunities to optimise the power/torque curve in an ac motor drive but this is outside my sphere of knowledge.
OK I'm out of this sub-topic.

 

[furnessvale]

Well can we use some examples ? Do you think a 90 mph geared 323 quicker to accelerate than a 100 mph geared EMU like a 360 etc ?

I have no idea and I did not pose that question.

I simply asked if a geared up 323 could still maintain its acceleration advantage over a 319.

So far, no one has answered that question.

 

[Domh245]

This is going off of Porterbrook's data: Given that the 323 kicks out 1,168kW compared to the 319s 990kW total, and the 323 has a mass of 119.8t compared to the 319's 140.3t, I suspect that even with gearing to 100mph, the 323 would still beat the 319.

 

[furnessvale]

This is going off of Porterbrook's data: Given that the 323 kicks out 1,168kW compared to the 319s 990kW total, and the 323 has a mass of 119.8t compared to the 319's 140.3t, I suspect that even with gearing to 100mph, the 323 would still beat the 319.

Thanks for that, I suspect you are correct.