Why So Many New EMU Classes?

[Kingfisher200262]

Obviously we need lots of EMUs, but is there any reason for quite so many new classes of......

We at CSRE believe that if the railway is to become more affordable and more efficient, large, single classes of train are the only way forward.

To cover all passenger rail requirements, we have promoted Polaris for Inter-City, Pacemaker for regional and Pulsar for metro and rural services, but these need not necessarily be the chosen products. The benefit of this kind of approach is, for example the use of one type of air conditioning unit across the whole gamut, with the economy of scale that this brings. This principle can be applied to a whole host of sub-systems... CCTV, PIS, brakes, traction, doors, windows etc etc.

What is most important however is the sharing of intellectual property, so that TOCs and ROSCOs can get competitive pricing for the same product from more than one train builder. I'm sure that if DfT owned the design rights to a "go anywhere" EMU or DMU and could offer the design for ROSCOs to invite prices for same, the unit cost of rolling stock would be driven down quite quickly.

We have been open about the fact that when our own products have recovered their development cost (which is currently amortised over about 200 vehicles), we will offer TOCs and ROSCOs the opportunity to use the designs, royalty free, to get competitive prices from other manufacturers, in competition with ourselves. In this way, a large number of "standard" vehicles, can be built by a number of manufacturers, relatively quickly.

This is how things should have gone forward with Networkers in the late 80s but we somehow ended up with two manufacturers building trains that looked the same, but with parts that weren't interchangeable and this has been a headache for the asset owners and TOCs ever since.

 

[Class377/5]

Obviously we need lots of EMUs, but is there any reason for quite so many new classes of them?

In the last few years, we've had (figures from Wikepedia, so not 100%):

332 (fourteen sets)
333 (eighteen sets)
334 (forty sets)
350 (sixty seven sets)
360 (twenty six sets)
375 (one hundred and twelve units)
376 (thirty six units)
377 (one hundred and eighty two units)

..plus DC equivalents, plus the 378/ 379/ 380/ new classes for Thameslink/ Crossrail...

Is there any real need for all these different types? Wouldn't it have been a lot easier to build one main class of 100mph stock with a variety that has doors at the end and one with doors in the middle?

Add in an additional class for 125mph trains (with doors at the end) capable of routes like Birmingham - Glasgow or London - Norwich.

Instead of three classes, we have a dozen different flavours of the same thing. This means we end up with awkward numbers of units to swap between operators (which has caused unnecessary complications).

Can anyone justify why we need so many classes?

(I understand *why* we have so many, as each TOC has bought a class specific to it, given the lack of central organisation)

I'm going to comment on the Electrostars as its what I know best.

There is little reason to have a 375/377 difference expect the software upgrades on them. Software can make them very different trains as when the 377/5 were having one update they could couple to another 377/5 with a different software package!

The 376 should be a different class as they are very different units. They don't have the inter unit connections and because of the seating design (due to the metro work they planned to do) means you need a separate class.

Now the 378 are a verison of the 376 but due to the fact you can get a wheelchair between carriages and the very different seating arrangement they got a different class. They could have become 378/3 and 378/4 to be honest.

The 375/6 were originally designed with Thameslink in mind. Sadly this never happened.

As for the 380, they should be a different class as they have 23m bodies compared to the 360/SWT units. Hence a jump in class from the 350/360.

Note as well that the original 350 were dv so giving them a separate class was a sensible idea.

The new Thameslink trains, the NXEMU's, will need a new class as they will be a completely new train and won't work with existing fleets.

As for the Networkers, the DC units were classed as 465/466 where as the AC were classed as 365. Sensible.

One thing with these trains I've spoke of is they have have the same body (as the 375/377 do but the 376/378 have a different door type) but inside and underneath they may be very different hence the need for different classes to assist train planning and engineering.

 

[tbtc]

I'm going to comment on the Electrostars as its what I know best.

There is little reason to have a 375/377 difference expect the software upgrades on them. Software can make them very different trains as when the 377/5 were having one update they could couple to another 377/5 with a different software package!

The 376 should be a different class as they are very different units. They don't have the inter unit connections and because of the seating design (due to the metro work they planned to do) means you need a separate class.

Now the 378 are a verison of the 376 but due to the fact you can get a wheelchair between carriages and the very different seating arrangement they got a different class. They could have become 378/3 and 378/4 to be honest.

The 375/6 were originally designed with Thameslink in mind. Sadly this never happened.

As for the 380, they should be a different class as they have 23m bodies compared to the 360/SWT units. Hence a jump in class from the 350/360.

Note as well that the original 350 were dv so giving them a separate class was a sensible idea.

The new Thameslink trains, the NXEMU's, will need a new class as they will be a completely new train and won't work with existing fleets.

As for the Networkers, the DC units were classed as 465/466 where as the AC were classed as 365. Sensible.

One thing with these trains I've spoke of is they have have the same body (as the 375/377 do but the 376/378 have a different door type) but inside and underneath they may be very different hence the need for different classes to assist train planning and engineering.

A very interesting answer

I liked the 165/ 365/ 465 numbering for three flavours of what were effectively three flavours of the same thing. That seemed a logical way to do things. If only the same could be said of other decisions!

 

[hairyhandedfool]

Yes, very little between them
The same could apply to 317, 318, and 319, then also 320, 321, and 322....

317/2s and 318s may be the same, I'm not sure about them, but 319s are not the same as the 317/1s. Electrically speaking, aside from the lights, controls and pantograph and most of the onboard MCBs, there is little that is similar. The brakes are also slightly different apparently.

The closest unit, electrically speaking, to the 319 is the 325.

--- old post above --- --- new post below ---

....As for the Networkers, the DC units were classed as 465/466 where as the AC were classed as 365. Sensible....

I was of the impression that the 365s were dual voltage or atleast planned as such), but WAGN didn't need the DC equipment and Southeastern didn't need the AC equipment. When WAGN received the Southeastern allocation the DC equipment was lost and AC equipment replaced.

 

[MCR247]

Yes, 365s were dual voltage, but they lost their DC when they went to WAGN

 

[Train wasp]

One question always comes to mind. Who decides the specification of new rolling stock? Is it the TOC or the leasing company? The only reason I ask this question is because a TOC can come and go but the rolling stock could be around a lot longer in theory. Just look at the voyagers and how awful they are to ride in. We could be using them for the next twenty year and that sends a shiver down my back.

 

[ainsworth74]

The plan was originally that the ROSCO's order new stock then the TOC's would then lease this new stock. However these days it tends to the DfT that are specifying new rolling stock orders.

 

[jopsuk]

I think the spec has a fair bit to do with the third party involved- the DfT, responsible for the franchising.

 

[Pumbaa]

One thing with these trains I've spoke of is they have have the same body (as the 375/377 do but the 376/378 have a different door type) but inside and underneath they may be very different hence the need for different classes to assist train planning and engineering.

Balls are they - they're basically the same bar a slightly improved TMS, which was then retrospectively upgraded across all the others anyway.

378s are the only different ones - new bodyshells, new kit under the floor.

378s are NOT a version of the 376 as you stated; both born out of different ideas, suit different markets and their external similarities are probably convenient as it meant Bombardiers designers could do a half-arsed job.

 

[Class377/5]

Balls are they - they're basically the same bar a slightly improved TMS, which was then retrospectively upgraded across all the others anyway.

378s are the only different ones - new bodyshells, new kit under the floor.

378s are NOT a version of the 376 as you stated; both born out of different ideas, suit different markets and their external similarities are probably convenient as it meant Bombardiers designers could do a half-arsed job.

I beg to differ as Bombardier called them 376 in the original tech specs drawing supplied to TfL. Now if the people making them put them with the 376 so did I.

 

[Pumbaa]

Differ all you want, the 378 is a halfway stepping stone to the Bombardier new-spec EMU being developed for TL bids among other things. Differences; 376 bogies are old Adtranz - 378s are new designs from Bombardier; traction kit is new from Bombardier rather than old stuff; bodyshell is the new design for increased crashworthiness and separated windows rather than ribbon glazing as well as different construction and internal support struts to support full width gangways - the list goes on.

Yes they look similar outside but that does not mean they're a version of a previous model.

 

[O L Leigh]

317/2s and 318s may be the same, I'm not sure about them, but 319s are not the same as the 317/1s. Electrically speaking, aside from the lights, controls and pantograph and most of the onboard MCBs, there is little that is similar. The brakes are also slightly different apparently.

Not so.

All of the Mk3 derived EMU's are compatible with each other and generally tend to differ only in details, and those do not have any bearing on their inter-operability.

Cl317/2's are very different from Cl318's even though they have the same body style. The Cl317's are geared for 100mph where the Cl318's are only cleared for 90mph. They also have different traction motors with different outputs. Cl317's and Cl319's actually have the same traction motors where the Cl321's have different ones, and yet Cl317's and Cl321's have successfully operated in multiple in the past. (Also, FCC have used Cl319's to provide motive power for Cl317 "drags" in the past.) Even their driving characteristics are broadly identical.

I would consider it a very safe bet that any driver who "signs" any one of the Mk3 EMU classes could easily find their way around any other class of EMU from the same family. It might take a moment or two to work out some of the differences (e.g. like which coach the main compressor lives under and, by extension, where it's MCB can be found), but it wouldn't take much longer than that.

The closest unit, electrically speaking, to the 319 is the 325.

Only in the sense that both are dual-voltage.

However, the Cl325 lacks a lot of the systems that a Cl319 has (e.g. door controls, autocoupler, passcoms, etc), therefore it could just as easily be argued that it is the least electrically similar. If anything, the most similar unit electrically to the Cl319 is the Cl321.

O L Leigh

 

[hairyhandedfool]

I was told by the traction inspector that whilst 319s and 317s can be used in multiple it is not desirable, I didn't meant to imply otherwise. The underfloor equipment carried by 319s is quite different to the 317/1.

IIRC (it has been more than five years since I've been trained on them), the AC power collected by a 319 is converted to DC (by the Main Transformer (MT)) and, with the DC supply, sent through a smoothing choke. Power is then supplied to the traction motors and the Main Alternator (MA). The MA supplies the 240v systems and other control systems through two windings.

ISTR, the 317/1 does not have a MT or a smoothing choke and the MA has an extra winding.

So whilst I can't vouch for the Traction motors being the same or different, the MA is different and the supply chain is different.

I was of the belief that the 325 was the same as the 319 traction wise (I can't say for door controls and the like), I don't have sufficient knowledge of the other units to compare.

As a 319 trained driver I had a two day conversion course for a 317/1.

 

[O L Leigh]

I'm a bit confused by your explanation. What's a Main Alternator and how does it differ from the transformer?

As I was taught, the job of stepping down the voltage for the various on-train systems is done by the transformer. Now it may be the case that the Cl319 does this as a two-step process using two different items of equipment to permit the unit to be dual-voltage, but the process itself is no different to what happens on a Cl317 with it's single transformer. Likewise, it doesn't matter that each class of unit steps down the power in a slightly different way if they were to be worked in multiple.

Cl317's do indeed have smoothing chokes as part of the traction circuit. You just can't see them because they are buried right in the middle of the PMOS between the traction equipment cases on one side and the thyristors and electronics on the other.

The source of my information about traction motors is The Railway Centre website.

However did they manage to make a Cl317 conversion course last two days...?! Was any reason given for these units not working in multiple? It sounds like a very strange situation and suggests to me a concern "just in case".

O L Leigh

 

[SouthEastern-465]

Exactly the same as the 450s and 444s then, which also have a pantograph space. Hence my original point...

To be fair I wasn't talking about the 'Desiro' units, and was refering to the 'Electrostar' units, and to be honest I don't know as much about 'Desiros'!

 

[MCR247]

To be fair I wasn't talking about the 'Desiro' units, and was refering to the 'Electrostar' units, and to be honest I don't know as much about 'Desiros'!

No, but you was saying why the 377s are in the AC section, when 444s and 450s are the same..

 

[SouthEastern-465]

No, but you was saying why the 377s are in the AC section, when 444s and 450s are the same..

Myself I can't remeber mentioning the 444s & 450s? I only explained the 3xx side of things not the 4xx.

But now now you mention it, they might of been numbered in the 4xx series because when they were ordered they replaced the 'Slammers which could only run on the 750v DC 3rd rail, and never ran on OHLE lines and never will to my knowledge as there are AC versions the 350s. And as for now I am sure SWT wouldn't need to run them on OHLE lines? But the same could be said for the Class 375s, and 376s...

 

[MCR247]

Myself I can't remeber mentioning the 444s & 450s? I only explained the 3xx side of things not the 4xx.

No, but someone asked why electrostar are 3xx and your reason isn't valid as its the same as desiros :roll:

 

[O L Leigh]

You're expecting the railways to be logical...? Don't you know that TOPS classifications are just drawn out of a hat?

O L Leigh

 

[SouthEastern-465]

No, but someone asked why electrostar are 3xx and your reason isn't valid as its the same as desiros :roll:

Fair enough.

I notice, most and nearly all new build purpose built 3rd rail units (Not designed for OHLE) have purpose built recess for future AC conversion as standard. So is there a regulation stating these have to be fitted I don't know?

 

[MCR247]

Yes, I think its a regulation

 

[Kingfisher200262]

I'm a bit confused by your explanation. What's a Main Alternator and how does it differ from the transformer?

O L Leigh

Could that be a motor alternator, rather than a main alternator? That's how ac is developed on loco hauled coaching stock. I'm not familiar with BR era EMUs but it sounds logical.

 

[hairyhandedfool]

I'm a bit confused by your explanation. What's a Main Alternator and how does it differ from the transformer?

I all honesty I don't know what the difference is, but I suspect there is a technical difference somewhere.

As I was taught, the job of stepping down the voltage for the various on-train systems is done by the transformer. Now it may be the case that the Cl319 does this as a two-step process using two different items of equipment to permit the unit to be dual-voltage, but the process itself is no different to what happens on a Cl317 with it's single transformer. Likewise, it doesn't matter that each class of unit steps down the power in a slightly different way if they were to be worked in multiple.

The post I first responded to said that 317, 318 and 319 units are so similar they could be the same class. My point was that the 319s are not the same. they may have the same basic system processes, but it is a different set of equipment to do it and even then there are differences in the process.

On the 319, the AC power is converted to DC, in then joins the bus for the DC supply, then passes through the smoothing choke to the Alternator which turns it all into AC power, but the Traction Motors (TM) are fed DC power.

My understanding of 317s is that the TMs are fed AC power from the Alternator/Transformer (whichever is the correct term) rather than DC. If this is not correct than maybe they are more similar than I thought/was told.

Cl317's do indeed have smoothing chokes as part of the traction circuit. You just can't see them because they are buried right in the middle of the PMOS between the traction equipment cases on one side and the thyristors and electronics on the other.

Oh okay, I guess that makes sense. You can't see it on a 319 either, but we weren't told of its existance on the 317.

However did they manage to make a Cl317 conversion course last two days...?!

To be fair I was a new driver at the time and I think the 'seasoned' drivers had a day (looking round the unit + practical handling). For the 'less experienced', they had some classroom stuff first to explain the difference, then a look at the unit itself in the afternoon at the depot and practical handling the next day (so a day and a half really).

Was any reason given for these units not working in multiple? It sounds like a very strange situation and suggests to me a concern "just in case".

From what I recall, they were talking about differences in the brakes, the 317 has 3.5 or 4.0 bar pressure IIRC, the 319 has only 3.0 bar, I don't honestly think that should be an issue, but I don't know exactly how the control information is sent between the units (obviously I know where it happens).

Although it was never said, I think there was also the worry of drivers taking a 319/317 pairing past Farringdon into City Thameslink (where the 317s can't operate by themselves and would basically be deadweight 'up the bank' to Blackfriars) and then onto the southern region in error (one driver had apparently already parked a 319 in the un-wired Platform 4 at Bedford!).

Fair enough.

I notice, most and nearly all new build purpose built 3rd rail units (Not designed for OHLE) have purpose built recess for future AC conversion as standard. So is there a regulation stating these have to be fitted I don't know?

The only modern DC unit I can think of atm without a pantograph well is the 460 GatEx units, the 'similar' 458s do have them though.

 

[O L Leigh]

On the 319, the AC power is converted to DC, in then joins the bus for the DC supply, then passes through the smoothing choke to the Alternator which turns it all into AC power, but the Traction Motors (TM) are fed DC power.

Yes, that makes some sense.

The Cl317's have three windings on the transformer; the primary winding being 25kV AC being fed directly from the OLE via the pan, the secondary winding being 900V which is rectified to DC for the traction motors, and the tertiary winding which provides 240V AC for the "hotel" systems (heat, light, etc). There is also a battery charger/rectifier which takes the 240V AC from the tertiary winding and rectifies it to DC and steps it down to 110V to charge the auxilliaries.

On OLE a Cl319 would be likely to do much the same things though, as you say, not necessarily using the same equipment. However, it still needs to work on CRE also, therefore I can see that the DC bus replicates the job of the secondary winding on the transformer and that, because the power isn't coming via the transformer, power for the "hotel" systems needs to be provided from the DC bus instead and that, for simplicity, this is what happens on the OLE also.

However, I fear you may have the smoothing chokes in the wrong place in your description as their job is to smooth out the AC and turn it into DC for the motors. On the CRE it is picking up DC power for it's DC motors, but obviously it needs to convert a certain amount to AC for the "hotel" systems.

My understanding of 317s is that the TMs are fed AC power from the Alternator/Transformer (whichever is the correct term) rather than DC. If this is not correct than maybe they are more similar than I thought/was told.

Nope. Cl317's have DC motors the same as the Cl319's. The first units to appear with AC motors were the Networker EMU family.

To be fair I was a new driver at the time and I think the 'seasoned' drivers had a day (looking round the unit + practical handling). For the 'less experienced', they had some classroom stuff first to explain the difference, then a look at the unit itself in the afternoon at the depot and practical handling the next day (so a day and a half really).

For a lot of your colleagues it would have been more of a traction refresher than a conversion course, as Cl317's have a long history on the MML.

From what I recall, they were talking about differences in the brakes, the 317 has 3.5 or 4.0 bar pressure IIRC, the 319 has only 3.0 bar, I don't honestly think that should be an issue, but I don't know exactly how the control information is sent between the units (obviously I know where it happens).

It would be through the brake wires via the coupler connector block. So if you select Step 2 in the front it will de-energise the brake wires in a certain sequence that will be replicated down the entire train.

I agree it shouldn't be an issue provided that each class had a broadly similar deceleration curve, but if one brakes much harder than the other then it would put stress on the coupler. Mind you, there are often huge variations in the braking performance of units within the same class anyway, so clearly it isn't much of a problem.

Although it was never said, I think there was also the worry of drivers taking a 319/317 pairing past Farringdon into City Thameslink (where the 317s can't operate by themselves and would basically be deadweight 'up the bank' to Blackfriars) and then onto the southern region in error (one driver had apparently already parked a 319 in the un-wired Platform 4 at Bedford!).

That sounds more likely. It wouldn't surprise me in the slightest if someone in Control forgot about the pairing and allowed it to continue "booked route" through the core and out into the wilds of the Southern.

The only modern DC unit I can think of atm without a pantograph well is the 460 GatEx units, the 'similar' 458s do have them though.

I wouldn't be surprised if these unit DO have a pan well but that they have been blanked out with a section of dummy roof, just like the Cl365's when they worked the South-Eastern division.

O L Leigh

 

[hairyhandedfool]

...On OLE a Cl319 would be likely to do much the same things though, as you say, not necessarily using the same equipment. However, it still needs to work on CRE also, therefore I can see that the DC bus replicates the job of the secondary winding on the transformer and that, because the power isn't coming via the transformer, power for the "hotel" systems needs to be provided from the DC bus instead and that, for simplicity, this is what happens on the OLE also.

The Alternator on the 319 has two windings (or whatever the correct term is), like the final two windings of the Transformer on the 317.

...However, I fear you may have the smoothing chokes in the wrong place in your description as their job is to smooth out the AC and turn it into DC for the motors. On the CRE it is picking up DC power for it's DC motors, but obviously it needs to convert a certain amount to AC for the "hotel" systems....

The smoothing choke simply flattens out any 'ripples' in the DC though doesn't it? There would be no need to turn the AC to DC on the 319 as this has already been done (either by the transformer or the substation on DC lines).

 

[O L Leigh]

Does it? I don't recall.

I've been back through my traction notes over the past couple of days in the course of replying to this thread and couldn't find a sufficiently good explanation of what the smoothing chokes are for, though my memory of my traction course seemed to suggest they were there to rectify the AC from the transformer to DC for the motors. However you may well be correct.

O L Leigh

 

[hairyhandedfool]

It just seems to me, to be a waste of equipment, if that is what it is for.

You said the 110v systems on the 317 are DC right? That being the case the Transformer is clearly capable of converting AC to DC, so why carry another piece of equipment for the same job when it isn't needed to do that?

Perhaps the Smoothing Choke on the 317 receives DC power from the first winding of the Transformer. The second winding would convert the DC supply back to AC for the 240v systems and the third would get it back to DC for the 110v systems.

I can't recall if the 110v systems are AC or DC on the 319s, this might provide an answer to what the difference between a Transformer and an Alternator is (AC would mean the Alternator might only convert DC to AC only, not vice-versa), the information would be on my old Laptop which no longer works.

I had a look at the Railway Centre website and it says multiple working for 317s and 319s is within class only, but for 321s is for classes 313 to 323 ???

 

[jopsuk]

In strict electrical terms, a "Transformer" cannot do AC to DC- they only step up/step down AC- they cannot do DC. Other methods are needed if you want to step DC up or down.

AC to DC converters are "Rectifiers"

DC to AC is an "Inverter"

 

[O L Leigh]

You said the 110v systems on the 317 are DC right? That being the case the Transformer is clearly capable of converting AC to DC, so why carry another piece of equipment for the same job when it isn't needed to do that?

Yes they are. These are the auxilliary systems that run from the batteries and include things like your CSR, PA, control circuits, emergency lighting and so on. I expect that a Cl319 has auxilliary battery supply for such things that run at precisely the same voltage in just the same way.

The reason why there is an additional rectifier associated with the battery charger is because it is on the 240V AC circuit that comes off the tertiary winding. Therefore it needs to rectify this to DC in order to charge the batteries.

However, as jopsuk says, transformers do not rectify AC to DC. All they can do is to step the voltage up or down.

Perhaps the Smoothing Choke on the 317 receives DC power from the first winding of the Transformer. The second winding would convert the DC supply back to AC for the 240v systems and the third would get it back to DC for the 110v systems.

Firstly, lets just get the three windings straight.

The primary winding is at 25kV AC direct from the OLE. This is not actually used for anything directly but, because of the way a transformer works, it must have a power feed from somewhere in order that voltage can be either stepped up or down.

A closer read of my traction manual shows that the secondary winding actually produces something in the region of 920V AC. This is the traction supply and will eventually find it's way to the motors, though more on that later.

The tertiary winding is at 240V AC. This is your on-train power supply for all other systems and, as outlined above, the circuit on which the battery charger/rectifier is located to produce your 110V DC supply.

Now, as I hinted above, I've had a closer read of my traction manual and have found a few more details about the traction supply that comes off the secondary winding.

As stated above, the traction supply comes out of the transformer at around 920V AC. This then goes to the thyristors to be converted into DC, but it is not yet ready to be used by the motors. First there is some physics to contend with.

As I'm sure you are aware, AC current when plotted as a graph looks like a sine wave.

When plotted as a graph, straight DC looks like a flat line.

The problem with rectified AC is that when it is plotted as a graph it isn't a flat line but instead looks like a series of humps where the voltage rises and falls from zero up to it's maximum and back to zero again.

This rectified AC is then sent to the smoothing chokes which smooth out the power to make it more like straight DC before sending the power to the motors at around 900V DC. This makes the power usable.

I can't recall if the 110v systems are AC or DC on the 319s, this might provide an answer to what the difference between a Transformer and an Alternator is (AC would mean the Alternator might only convert DC to AC only, not vice-versa), the information would be on my old Laptop which no longer works.

If the 110V supply is coming from the batteries it must be DC.

However, I can still see the need for an inverter (to convert DC to AC) on a Cl319. As I said earlier, the Cl319 still requires a 240V AC supply for it's on-train systems. While this is easy to come by for a unit on the OLE (from the transformer's tertiary winding on a Cl317, for example), a unit that runs on the CRE has no ready access to AC power. Therefore it needs to generate it's own from the DC supply that it is getting via it's shoes.

I had a look at the Railway Centre website and it says multiple working for 317s and 319s is within class only, but for 321s is for classes 313 to 323 ???

Hokum. It's a useful website but not totally authoritative.

I can see the reason why Cl319's are listed as multiple working within class only because of the risk of taking an AC unit along for a ride through the core and out onto the Southern. It's not a technical restriction but an operational one.

As for Cl317's being restricted to working within class only this is totally wrong. NSE on the Northampton lines worked them in multiple with Cl321's in service and FCC use Cl319's to permit "drags". I myself have worked a mixed ECS formation comprising both Cl317's and Cl315's, and such workings are not uncommon. On the GN side of FCC all their classes are permitted to work in multiple for ECS and assistance purposes.

O L Leigh

 

[466.networkers]

No, but you was saying why the 377s are in the AC section, when 444s and 450s are the same..

Myself I can't remeber mentioning the 444s & 450s? I only explained the 3xx side of things not the 4xx.

But now now you mention it, they might of been numbered in the 4xx series because when they were ordered they replaced the 'Slammers which could only run on the 750v DC 3rd rail, and never ran on OHLE lines and never will to my knowledge as there are AC versions the 350s. And as for now I am sure SWT wouldn't need to run them on OHLE lines? But the same could be said for the Class 375s, and 376s...

No, but someone asked why electrostar are 3xx and your reason isn't valid as its the same as desiros :roll:

Fair enough.

I notice, most and nearly all new build purpose built 3rd rail units (Not designed for OHLE) have purpose built recess for future AC conversion as standard. So is there a regulation stating these have to be fitted I don't know?

Yes, I think its a regulation

All new build DC EMU's have a recess in one TSO (or equivalent) for a possible future addition of a pantograph and conversion to AC running.

Some of the newer EMUs have already a panto fitted such as the 375/6s and 377/2s and /5s (obviously).

I think this came into effect a few years back, 2001/2002 are sticking in my mind for some reason.

All this is why the newer EMUs are in the 3xx TOPS category and not the 4xx as they have (or can) possibly be used on AC, whether now or in the future.

Makes sense if you think about it.