Southern Railway EMU designation codes.

[Xenophon PCDGS]

In what year was the first of these used and was there any person in particular who was credited with the introduction of them?

 

[30907]

The LBSCR used codes, though pedantically these were AC stock
https://www.bloodandcustard.com/#SRMultipleUnits
The 2-car conversions (WIM and SL) date from 1929, next up were the Brighton mainline stock which AFAIK had codes from the outset.
The SR had a penchant for fixed formations of hauled stock as well which were typically "coded." (3-set, 3-lav, 3-cor....)
The one code that AFAIK was unofficial was Sub(urban) - official documents such as Carriage Workings simply show "3" (4 in BR days!).

 

[Big Jumby 74]

The one code that AFAIK was unofficial was Sub(urban) - official documents such as Carriage Workings simply show "3" (4 in BR days!).

Sometimes the origins of things has now been long lost in history, but (SWD at least), as you say, documentation wise (we) referred to them on paper as '4' or '8', which made diagramming easier (pencil & paper) as there were far more of them than their 4 EPB cousins when I started, but the units themselves in my time all had '4 SUB' printed on the yellow ends just above the left hand buffer (as one looks at the front of the unit - either end), similar to other EMU stock.
Again, SW wise in my case (but also elsewhere), this may have originated from a wish by the ops dept. to highlight to staff in general the operational area restriction(s) that were imposed on them, as per 'Note E' in the Appendix to the CWN, which reads;

"4-(Sub) Units must not run in passenger services between Pirbright Junction and Bournemouth or below Gillingham and Sevenoaks. Empty movements within these areas may be arranged provided lighting and heating circuits are made inoperative by the CM&EE Dept. Lighting and heating will, however, be made available as necessary in the driving cabs and in these circumstances, the guard may ride in the rear driving cab".

This was IIRC tied in with the voltage differences in the suburban area. I forget exactly, but something about the 660v / 750v variation that existed back then?

 

[contrex]

the units themselves in my time all had '4 SUB' printed on the yellow ends just above the left hand buffer (as one looks at the front of the unit - either end), similar to other EMU stock.
Again, SW wise in my case (but also elsewhere), this may have originated from a wish by the ops dept. to highlight to staff in general the operational area restriction(s) that were imposed on them, as per 'Note E' in the Appendix to the CWN, which reads;

"4-(Sub) Units must not run in passenger services between Pirbright Junction and Bournemouth or below Gillingham and Sevenoaks. Empty movements within these areas may be arranged provided lighting and heating circuits are made inoperative by the CM&EE Dept. Lighting and heating will, however, be made available as necessary in the driving cabs and in these circumstances, the guard may ride in the rear driving cab".

This was IIRC tied in with the voltage differences in the suburban area. I forget exactly, but something about the 660v / 750v variation that existed back then?

The painting of unit designations such as '4 EPB', '4 SUB' etc on the unit ends came quite far on in my love affair with the Southern Electric, which probably started around 1956 when I was a very little boy and 1925 type suburban units ran past our house which backed on to the Herne Hill - Tulse Hill spur, and took me to relatives in Orpington and Balham.

I had always understood that units before the 1951 type (that is before the EP stock era) were banned from the 750v Kent Coast and Bournemouth electrifications because they had lighting and heating circuits fed directly from the 660v line. Strings of bulbs and heating elements in series. 1951 and later stock had motor generators for lighting and control (with batteries) and could handle 750v. I remember the lights on SUBs for example used to dim at the moment of starting and go out if the unit was momentarily gapped. In view of this I am puzzled that after the PULs and PANs were withdrawn from the Brighton line services around 1966 some were reformed into 6 COR units which 'helped out' on some SE division Kent Coast services in summer 1967 (not very successfully I gather). I don't know if they had different heat/light arrangements or if they were altered. Or only ran in daylight in summer with light/heat isolated?

 

[30907]

I had always understood that units before the 1951 type (that is before the EP stock era) were banned from the 750v Kent Coast and Bournemouth electrifications because they had lighting and heating circuits fed directly from the 660v line. Strings of bulbs and heating elements in series. 1951 and later stock had motor generators for lighting and control (with batteries) and could handle 750v. I remember the lights on SUBs for example used to dim at the moment of starting and go out if the unit was momentarily gapped. In view of this I am puzzled that after the PULs and PANs were withdrawn from the Brighton line services around 1966 some were reformed into 6 COR units which 'helped out' on some SE division Kent Coast services in summer 1967 (not very successfully I gather). I don't know if they had different heat/light arrangements or if they were altered. Or only ran in daylight in summer with light/heat isolated?

Checking back with Bloodandcustard.com (as always!) the pre-war "express units" also had a motor generator - it was only the suburban stock that didn't.
The SED was an all-EPB area from very soon after the Kent Coast 1959 electrification (possibly excepting the Holborn-Wimbledon service).

 

[Taunton]

"4-(Sub) Units must not run in passenger services between Pirbright Junction and Bournemouth or below Gillingham and Sevenoaks. Empty movements within these areas may be arranged provided lighting and heating circuits are made inoperative by the CM&EE Dept. Lighting and heating will, however, be made available as necessary in the driving cabs and in these circumstances, the guard may ride in the rear driving cab".

This has been a long-running discussion on here, as the Pirbright Junction one was described as introduced in 1967 with the Bournemouth electrification because it was 850v on the new section, which among other things allowed 4-SUBs to run by themselves to Eastleigh works for overhaul, where they had previously been hauled. It was in a Modern Railways magazine article in 1967, which by its knowledgeable content appeared to have been written, or at least briefed, by one of the electrification engineers.

A number on here, including those apparently closely connected with the subsequent operation there, completely disagree with the 850v part, and say it was just as standard as the rest of the Southern at 750v, where the SUBs were allowed. But here is a description of the ban, albeit without giving the reason. Possibly it was some maximum overload setting or similar on that section before the circuit breakers came out.

There seems no reason for the 4-SUB to run on the new Kent electrification, and indeed they were fully cleared out from the Eastern Section suburban area around the same time as this was introduced.

 

[Big Jumby 74]

Must admit have never heard (or seen) anything myself, even when on the job to suggest there were any sections at 850v ! It was always a case of 750v (in general terms) and accepted as such. Sure anyone involved with the old EC rooms at Raynes Park and the like, might know? Could it be that with the then brand new juiced section heading west in '67, that (perhaps) 850v was trialled for a period? Outside of my knowledge I'm afraid.

Interesting that with the introduction of the Desiro's and their heftier draw than 400 stock, the network (as I understand) has ended up with more unseen restrictions on traction current at certain locations on the old SWML 'race track' and down the PDL, West of Poole being the only section that is perhaps openly recognised as being restrictive?

 

[contrex]

Checking back with Bloodandcustard.com (as always!) the pre-war "express units" also had a motor generator

That'll teach me to read Blood & Custard articles more carefully - I was actually looking at pics of 6CORs at various SED locations the other day.

== Doublepost prevention - post automatically merged: 17 Feb 2023 ==

A Network Rail electrification engineer advised me on the uk.railway Usenet group around 20 years ago that the '850v on the Bournemouth electrification' was a myth started by an error in a magazine article. It was 750v. The reason why SUBs and other surviving SR-design EMUs were banned on the Kent Coast and Bournemouth electrifications was because their lighting and heating circuits were designed for 660v and would have malfunctioned on 750v.

== Doublepost prevention - post automatically merged: 17 Feb 2023 ==

A number on here, including those apparently closely connected with the subsequent operation there, completely disagree with the 850v part, and say it was just as standard as the rest of the Southern at 750v, where the SUBs were allowed.

When the SUBs were operational, the only 750v areas (where SUBs were banned unless their heating & lighting circuits had been isolated) were west of Pirbright Junction, and further out in Kent Sevenoaks or Gillingham, in other words, the 1967 Bournemouth and 1959-62 Kent Coast schemes.

 

[Big Jumby 74]

'850v on the Bournemouth electrification' was a myth started by an error in a magazine article. It was 750v

Comforting to know. May be going a bit what-sit in my later years, but didn't think I would have got that wrong after half a lifetime on the job...

 

[contrex]

Comforting to know. May be going a bit what-sit in my later years, but didn't think I would have got that wrong after half a lifetime on the job...

There is a lot of mumbo-jumbo talked by some people about electrification. A DC railway supply is not like the household mains, where you can expect the voltage to be fairly close to a defined value. At a railway substation e.g. on the Bournemouth scheme, the busbar voltage might float up to 900v or a little bit more with no train in section, and the voltage seen by a train, drawing max power in the section but some way from the substation might go down well below 500. I understand that on 750v nominal the voltage used for timing purposes is 675v (90% of nominal).

Voltage can vary to +20/-33% of nominal and so at a nominal voltage of 750 V, the voltage at the shoegear could be as high as 900 V under very light loading conditions; this could damage electrical equipment, particularly heaters, on 660 V or 630 V stock, which would have been designed to withstand a maximum voltage of about 800-820 V. It was generally permitted for 660 V stock to travel on 750 V lines as long as the heaters were disconnected.

 

[Big Jumby 74]

Thank you for the clarity re 750v, not my sphere as it were in career terms.

 

[contrex]

I recently read somewhere that after 1967, if SUBs had to go to Eastleigh for certain kinds of attention, the heating and lighting supply fuses were to be removed, and the controller to stay in 'series'. Don't know how accurate that is.

 

[Gloster]

I will add that I also always understood that it was the 660v versus 750v discrepancy that was the reason for the restriction.

 

[Surreytraveller]

I believe London Underground is (or was before the S7/8 stock) at 660v too, which makes sense where it interacts with the Southern

 

[etr221]

I believe London Underground is (or was before the S7/8 stock) at 660v too, which makes sense where it interacts with the Southern

It's actually driven by the reverse: the first bit of what was to become the Southern Electric was actually installed by the Metropolitan District, the LSWR following their standard (but dispensing with the centre 4th rail). But quite what the (nominal) voltage was I've never been totally certain - I've seen figures ranging from 600v to 660v (and think it's varied over the years).

And my understanding is that a change to a nominal 750v was planned (or at least intended - if only as an aspiration for many years) following the Kennedy Report on railway electrification in 1920...

 

[Snow1964]

It's actually driven by the reverse: the first bit of what was to become the Southern Electric was actually installed by the Metropolitan District, the LSWR following their standard (but dispensing with the centre 4th rail). But quite what the (nominal) voltage was I've never been totally certain - I've seen figures ranging from 600v to 660v (and think it's varied over the years).

And my understanding is that a change to a nominal 750v was planned (or at least intended - if only as an aspiration for many years) following the Kennedy Report on railway electrification in 1920...

My understanding is the LSWR electrified its early sections at 600v (+400v outside rail, -200v centre rail). These being Hammersmith-Richmond and Putney-Wimbledon including the now closed line to Kensington Olympia that looped near south side of Shepherds Bush

The LSWR added a section to North Acton for the LNWR trains in 1916

At some stage the voltage was changed to +600v outer rail and 0v centre rail which was bonded to a running rail.

Later sections the voltage was increased to 660v, and Southern used this voltage for the suburban area.

750v came later and was initially on the post war schemes, gradually the inner area was changed to this nominal voltage, although I understand it is nearer 790-800v at the transformers in the substations.

I think the new Underground S stock is wired to accept a change from 600v to 750v, but not sure how many substations the higher voltage has been rolled out to.

The earliest unit designation I can find is E
I assume this was just an abbreviation of LSWR 3car units E1-E84 which were the original units for the Waterloo suburban electrification (to Claygate, Hampton Court, Kingston loop, etc)

 

[etr221]

My understanding is the LSWR electrified its early sections at 600v (+400v outside rail, -200v centre rail). These being Hammersmith-Richmond and Putney-Wimbledon including the now closed line to Kensington Olympia that looped near south side of Shepherds Bush

While LSWR lines, Putney Bridge-Wimbledon and Studland Road (west of Hammersmith)-Richmond were electrified c1905 as part of the MDR electrification project (so four rail) - quite who was responsible for what at that point is one of those little mysteries... At this point all other (LSWR and - to Richmond - NLR/LNWR) trains remained steam.

East Putney-Wimbledon would have been converted to have 4th (centre) rail at earth by the time of the LSWR's own electrification in 1915 (for use also by LSWR trains).

The LSWR line from Kensington (Addison Road) round to Hammersmith Grove Road and Studland Road Junction was never electrified. From Studland Road to Turnham Green a second pair of tracks were provided c1910 to segregate MDR (electric) and LSWR (steam) use (I forget details). LSWR steam service withdrawn 1916, the lines they used fell into disuse... (and off topic)
LNWR (NLR) electric service to Richmond (from 1915/16) used four rail electrification, and only changed to three rail in the 70s/80s, with Gunnersbry-Richmond being modified to suit.

 

[stuu]

I think the new Underground S stock is wired to accept a change from 600v to 750v, but not sure how many substations the higher voltage has been rolled out to.

All of it is now, AFAIK, except Rayners Lane-Uxbridge and Finchley Road-Wembley because of the shared running

 

[etr221]

All of it is now, AFAIK, except Rayners Lane-Uxbridge and Finchley Road-Wembley because of the shared running

What is status of Barons Court-Ealing Common/Hanger Lane Jn (shared District & Piccadilly)?

 

[stuu]

What is status of Barons Court-Ealing Common/Hanger Lane Jn (shared District & Piccadilly)?

Good question, I suspect it is in fact Acton Town-Uxbridge which is still 630V. There's no connection east of Acton between the Picc and District any more

 

[eman_resu]

My understanding is the LSWR electrified its early sections at 600v (+400v outside rail, -200v centre rail)

Purely out of curiosity, are there any records as to the reason why this configuration was selected?

 

[etr221]

My understanding is the LSWR electrified its early sections at 600v (+400v outside rail, -200v centre rail).

Purely out of curiosity, are there any records as to the reason why this configuration was selected?

As above, on the LSWR, to provide for MDR trains exercising running powers. The choice by the MDR - together with the Yerkes group tubes and the Metropolitan - is a matter of Underground history, and is discussed in various books on the subject - beyond which it's a case of searching through the archives.

 

[nw1]

Sometimes the origins of things has now been long lost in history, but (SWD at least), as you say, documentation wise (we) referred to them on paper as '4' or '8', which made diagramming easier (pencil & paper) as there were far more of them than their 4 EPB cousins when I started, but the units themselves in my time all had '4 SUB' printed on the yellow ends just above the left hand buffer (as one looks at the front of the unit - either end), similar to other EMU stock.

It appears this practice ('4' or '8' without any indication of class) was later applied to 455s, presumably for a similar reason - they were the dominant type (in fact the only type on the SWD inner suburban lines for a good number of years, IIRC).

 

[etr221]

AIUI, until made up to four coaches in the 1940s, the original Southern Electric Suburban units (3 coach) were officially classified '3' (with later reference to them as '3-SUB' being erroneous), only when augmented (and having to be distinguished from other 4 coach units) did they acquire the '-SUB'. So I'm not surprised that old habits died hard and them being referred to as '4'.

 

[Taunton]

One does wonder why the awkward suburban arrangement, of 8-car trains made up of two 3-car sets, plus an unpowered and no controls 2-trailer in between, was perpetuated for so long, and indeed extended from the Waterloo lines where it started to the rest of the Southern. What a nuisance for shunting, dividing trains, storing in sidings, etc. However did it take a generation to think about putting the trailers inside to make 4-car sets.

 

[Snow1964]

One does wonder why the awkward suburban arrangement, of 8-car trains made up of two 3-car sets, plus an unpowered and no controls 2-trailer in between, was perpetuated for so long, and indeed extended from the Waterloo lines where it started to the rest of the Southern. What a nuisance for shunting, dividing trains, storing in sidings, etc. However did it take a generation to think about putting the trailers inside to make 4-car sets.

It is obvious for the early 3car sets, passenger numbers grew too much for pairs of units, so they added extra in the middle for busy peak hour trains.

I think continuing the practice was more to do with ratio of first class and third class, being different on peak and off-peak trains.

During the war, the first class on suburban was stopped for the duration, so no longer needed to change the ratio at different times of the day.

80+ years later still don't offer First class on suburban, instead standing and rock hard seats are modern offering, with trains of inappropriate seating capacity at much of the day to simplify operations.

 

[30907]

One does wonder why the awkward suburban arrangement, of 8-car trains made up of two 3-car sets, plus an unpowered and no controls 2-trailer in between, was perpetuated for so long, and indeed extended from the Waterloo lines where it started to the rest of the Southern. What a nuisance for shunting, dividing trains, storing in sidings, etc. However did it take a generation to think about putting the trailers inside to make 4-car sets.

The decision was taken in 1937 and depended on building new 6-a-side stock, allowing increased capacity without infrastructurealterations. Detail here:
https://www.bloodandcustard.com/SR-AugSUB.html

 

[etr221]

The decision was taken in 1937 and depended on building new 6-a-side stock, allowing increased capacity without infrastructurealterations. Detail here:
https://www.bloodandcustard.com/SR-AugSUB.html

While the new 6-a-side steel coaches - either as complete units or individual augmentation trailers - were indeed part of the augmentation project, they were only needed as result of the need for more coaches.
The mystery remains as to why the LSWR and Southern had opted for the 2-car trailer unit, to work with 3 car motor sets, option in 1920, and then continued with it, rather then going for 4 coach units at an earlier stage in the 1920s.