Class 312 EMUs

[90sWereBetter]

The 312s were built in the mid-1970s, and indeed some of the units may have entered service after the final 313 units were built. With that in mind, I was wondering why the 312s were built as slam-door stock? Was it just that a 90mph EMU design was needed, and with the PEP stock still in prototype form, it was decided to use the Class 310 design as a stopgap? It's just that the 312s being scrapped in the early 2000s after only about 25 years service seems a bit of a waste of good stock.

Were there any considerations given to refurbishing 312s with sliding doors? I imagine it would have been prohibitively expensive anyway, but it might have unlocked another 15-20 years of service from the units, which might have made such a project viable.

 

[MatthewRead]

The 312s were built in the mid-1970s, and indeed some of the units may have entered service after the final 313 units were built. With that in mind, I was wondering why the 312s were built as slam-door stock? Was it just that a 90mph EMU design was needed, and with the PEP stock still in prototype form, it was decided to use the Class 310 design as a stopgap? It's just that the 312s being scrapped in the early 2000s after only about 25 years service seems a bit of a waste of good stock.

Were there any considerations given to refurbishing 312s with sliding doors? I imagine it would have been prohibitively expensive anyway, but it might have unlocked another 15-20 years of service from the units, which might have made such a project viable.

I have to agree considering the oldest units were little more than 30 years old when they were withdrawn but still look at the 1983 tube stock on the Jubilee line oldest trains 15 years old and the Evening Star the last ever Steam engine to be built in Britain only lasted for 8 years in regular service.
I to wish the 312 units could have lasted a bit longer as other EMUs of a similar design lasted much longer.

 

[yorkie]

Were there any considerations given to refurbishing 312s with sliding doors?

I doubt it, a quick look at the number of (single leaf) doors involved would rule it out!

 

[notadriver]

The replacement for the 312 was the 317 surely superior in every way ?

 

[chubs]

The replacement for the 312 was the 317 surely superior in every way ?

This. Having travelled on the 312's in Great Eastern days, they were horrid.

 

[Islineclear3_1]

Well the last of the slam door 4Veps rolled off the production line in about 1974 along with the new build/Mk 1 conversions for 4REP/TC stock so I guess all these designs were based upon proven stock where quick replacements were necessary.

I can't remember if the 312's were compatible with the Clacton 309s as I don't recall ever seeing them run together

 

[theblackwatch]

There was a lot of cross-over between the various generations of stock. As mentioned, the last 4-VEPs, which were basically Mk.1, rolled off the production line in 1974 - yet the 310s, which were to a Mk.2 design, appeared in the mid 60s.

The first 312s appeared in 1975, but it was 1978 when the last examples entered service, by which time most if not all of the 313s were also in use.

 

[jopsuk]

It's amazing that slam doors lasted so long in new-build given the mark 1 based Class 303s had sliding doors in 1959!

 

[Nym]

Or Standard Stock as far back as 1923...(!)

 

[Taunton]

I think I am right in saying that in 1976 when the 312s were introduced there were no sliding door vehicles at all apart from on inner suburban services, and even then only for a few electric unit types. Everything else was slam door. The jigs were in any event available at the works from the 310 production. The first HSTs were only starting to be built at the time. Apart from the simultaneously new 313s, the only power door stock I can recollect on any London BR service at the time were the LNER-designed 1949 inner suburban units on Liverpool Street to Shenfield.

Some of the pleasantest stock of all was when various of the 1960-era slam door electric units were given heavy interior rebuilds in the early 1980s, with new and better seats, thoroughly draughtproofed doors, inter-car gangways, etc. Unfortunately the 312s were too new to qualify for this work.

I can't remember if the 312's were compatible with the Clacton 309s as I don't recall ever seeing them run together

I understood that they were technically mu compatible but nothing else was permitted to run in multiple with the Clactons due to the different maximum speeds and acceleration performance - I recall Cecil J Allen's amazement that one had accelerated from rest to 100mph within three minutes.

 

[RichmondCommu]

It's amazing that slam doors lasted so long in new-build given the mark 1 based Class 303s had sliding doors in 1959!

No only that but before WW2 the LNER had designed EMU's to run on the Woodhead route that had sliding doors!

 

[Taunton]

No only that but before WW2 the LNER had designed EMU's to run on the Woodhead route that had sliding doors!

They were actually designed and built by a Metro-Cammell/Birmingham RCW joint team, who also did the 1938 Wirral units for the LMS and the O stock for London Transport, all of which are pretty standardised. The LNER ordered 100 units, which were delivered after WW2, 92 for the Shenfield line (mentioned above) and 8 for the Manchester suburban operations on the Woodhead route.

 

[RichmondCommu]

They were actually designed and built by a Metro-Cammell/Birmingham RCW joint team, who also did the 1938 Wirral units for the LMS and the O stock for London Transport, all of which are pretty standardised. The LNER ordered 100 units, which were delivered after WW2, 92 for the Shenfield line (mentioned above) and 8 for the Manchester suburban operations on the Woodhead route.

Two railway builders now long gone of course. Without checking elsewhere did RCW build some of the class 33's? I seem to remember reading that RCW's factory was close by to the Snow Hill - Wolverhampton line but again I can't be certain.

Nevertheless in my opinion the LNER were streets ahead in their designs for suburban rolling stock, as were the LMS. I wonder as to what else they might have developed if it hadn't been for WW2 .

 

[jimm]

The 312s were built in the mid-1970s, and indeed some of the units may have entered service after the final 313 units were built. With that in mind, I was wondering why the 312s were built as slam-door stock? Was it just that a 90mph EMU design was needed, and with the PEP stock still in prototype form, it was decided to use the Class 310 design as a stopgap? It's just that the 312s being scrapped in the early 2000s after only about 25 years service seems a bit of a waste of good stock.

Were there any considerations given to refurbishing 312s with sliding doors? I imagine it would have been prohibitively expensive anyway, but it might have unlocked another 15-20 years of service from the units, which might have made such a project viable.

Fundamental point is that the PEPs were 75mph inner suburban stock, intended for shorter journeys. The Great Northern electrification needed something swifter and better suited to journeys out to the likes of Stevenage, Hitchin and Royston and able to get through the two-track section across Welwyn Viaduct nice and quick, hence the 90mph 312, a souped-up 310, based on what was considered a pretty robust bit of kit.

 

[Taunton]

Two railway builders now long gone of course. Without checking elsewhere did RCW build some of the class 33's? I seem to remember reading that RCW's factory was close by to the Snow Hill - Wolverhampton line but again I can't be certain.

They built all the 33s, and also the 26s/27s, which had a common body, along with the class 81 electrics, many first generation dmus and even more Mk 1 hauled stock (no power doors there), plus a lot for export. They were lined up to build some of the 1962 tube trains for the Underground, but went out of business and these were transferred to Metro-Cammell. They seem to have had a lot of joint projects with the latter over time. The factory was indeed alongside the Snow Hill line, in Smethwick.

 

[Philip Elliott]

It's amazing that slam doors lasted so long in new-build given the mark 1 based Class 303s had sliding doors in 1959!

The 303s were not Mk.1 based - the only overhead unit that was, was the AM9.

 

[notadriver]

I think I am right in saying that in 1976 when the 312s were introduced there were no sliding door vehicles at all apart from on inner suburban services, and even then only for a few electric unit types. Everything else was slam door. The jigs were in any event available at the works from the 310 production. The first HSTs were only starting to be built at the time. Apart from the simultaneously new 313s, the only power door stock I can recollect on any London BR service at the time were the LNER-designed 1949 inner suburban units on Liverpool Street to Shenfield.



Some of the pleasantest stock of all was when various of the 1960-era slam door electric units were given heavy interior rebuilds in the early 1980s, with new and better seats, thoroughly draughtproofed doors, inter-car gangways, etc. Unfortunately the 312s were too new to qualify for this work.







I understood that they were technically mu compatible but nothing else was permitted to run in multiple with the Clactons due to the different maximum speeds and acceleration performance - I recall Cecil J Allen's amazement that one had accelerated from rest to 100mph within three minutes.

They were not compatible. The electrical and air connections are in the centre of a 312 which isn't gangwayed but at the side of the gangwayed 309 in common with other gangwayed stock.

The different acceleration rates are irrelevant. 310s and 312s were coupled together. Besides a 4 car 312 was rated at 1080 hp and a 4 car 309 1128 hp - surely not too different ?

 

[AM9]

Fundamental point is that the PEPs were 75mph inner suburban stock, intended for shorter journeys. The Great Northern electrification needed something swifter and better suited to journeys out to the likes of Stevenage, Hitchin and Royston and able to get through the two-track section across Welwyn Viaduct nice and quick, hence the 90mph 312, a souped-up 310, based on what was considered a pretty robust bit of kit.

Surely the 312s were just updated (rather than souped-up) 310s. The 310s were designed for the London outer suburban services when the WCML electrification reached Euston. Previously, a few of the NW class 304s covered, but they were 75mph stock so were difficult to accomodate with LHCS stock paths. The 310s had an acceleration rate of 1.1mph/s/s to a 90mph max, which was a compromise between the 1.3-1.4mph/s/s of the 304s and the typical 0.8mph/s/s of a class 81-86 + 9 express.
When the GE services were expanded in the mid '70s there was a need to interleave the outers with the Clactons and the class 47 + 9 Norwich expresses. The speeds between Shenfield and London weren't an issue for the 75mph stock but beyond Shenfield, there was plenty of class 309 and Class 47 LHCS running at speeeds up to 100mph. The 310/312 design's 90mph with 1.1mph/s/s was a good compromise for running in with the class 309s which typically in a 2+4+4 set could attain 0.9mph/s/s on their way to 100mph.*
The main difference between the two types was that by the time the 312s were made, the safety rules meant that flat widscreens replaced the wrap-around ones originally put on the 310s.

* In the '60s when the 309s were introduced, the service between Shenfield and Chelmsford at under 8 minutes start to stop for the 9.5 miles was the fastest in the world. A clear indicator of the gains brought by 25kV electrification.
--- old post above --- --- new post below ---

They were not compatible. The electrical and air connections are in the centre of a 312 which isn't gangwayed but at the side of the gangwayed 309 in common with other gangwayed stock.

The different acceleration rates are irrelevant. 310s and 312s were coupled together. Besides a 4 car 312 was rated at 1080 hp and a 4 car 399 1128 hp - surely not too different ?

Other than when they started extending the 2-car 309/1s with ex-DMU and LHCS coaches, I've never seen a 309 coupled to anything but other 309s. They were quite conventional EMUs with GEC DC motors fed from transformers via rectifiers but their performance always seemed so much better than the 4-CIGs etc. as the ac power supply wasn't compromised like the 750VDC 3rd rail supply was (and still is).

 

[notadriver]

As far as I understand all 310s were 75 mph only whereas 312s came in two sub classes. The London midland were 75 mph and Great Eastern 90 mph.

Are you sure about the 304s ability to accelerate ? They had 828 hp and i remember like a 305 4 car set that went to Bishops Stortford they were incredibly slow to accelerate. I doubt they bothered the 310/312 units.

 

[AM9]

They were actually designed and built by a Metro-Cammell/Birmingham RCW joint team, who also did the 1938 Wirral units for the LMS and the O stock for London Transport, all of which are pretty standardised. The LNER ordered 100 units, which were delivered after WW2, 92 for the Shenfield line (mentioned above) and 8 for the Manchester suburban operations on the Woodhead route.

The Shenfield units had 4x157hp motors whereas the Manchester DC units (ISTR) had 4x185hp versions.

 

[notadriver]

Other than when they started extending the 2-car 309/1s with ex-DMU and LHCS coaches, I've never seen a 309 coupled to anything but other 309s. They were quite conventional EMUs with GEC DC motors fed from transformers via rectifiers but their performance always seemed so much better than the 4-CIGs etc. as the ac power supply wasn't compromised like the 750VDC 3rd rail supply was (and still is).

Would I be right in saying the Southern EMUs (4REPs excepted) had EE507 motors designed originally for 75 mph operation. These motors were derived from the Brighton Belle also 75 mph units ? Those 309s were designed for 100 mph from the outset and were given the muscle to achieve that.

 

[AM9]

As far as I understand all 310s were 75 mph only whereas 312s came in two sub classes. The London midland were 75 mph and Great Eastern 90 mph.

Apologies, I do believe that the 310s were 75mph, (so maybe the 304s weren't posh enough for the WCML south ). All the 312s were 90mph though.

Are you sure about the 304s ability to accelerate ? They had 828 hp and i remember like a 305 4 car set that went to Bishops Stortford they were incredibly slow to accelerate. I doubt they bothered the 310/312 units.

The acceleration figure is the maximum which probably kicked in at around 20-40mph, i.e. well before the effects of the balancing speed. The 304s like all the GE/LTS outers were basically suburban compartment stock and by modern standards were pretty light. Their lower gearing meant that the acceleration was good for getting away between stations along the Southend line but that acceleration ran out on the longer stretches between stations of the GEML. I remember the 17:42 which I caught at Shenfield for Colchester would clearly drag itself up to 75mph only to get in the way of following Clacton or Norwich expresses. The 312s seem to keep ahead as their gearing moved the peak acceleration rate speed up a bit and they could run smoothly at 90mph for most of the open stretches.

 

[notadriver]

The 312/2s are showing as 75 mph geared units. Maybe it's to retain comparability with 310s. In any case 310s were easily able to exceed 75 even uphill. I remember speeds well above 80 on the speedo going towards Watford Jct from Euston.

Looking at weights. The online info gives 304s as 151 tons and 312s as 156 tons so the 304s do have a small advantage.

In terms of ability 312s operating out of Kings Cross could sustain 80 mph on that 1/200 climb to Potters Bar. I'd be surprised if a 304 could manage much past 65.

 

[Wivenswold]

Perhaps I'm the only person who misses them. They were toasty warm in the winter and cool in the summer with all of those opening door windows. They could also swallow-up a crowded platform but unfortunately anyone standing would have issues keeping their balance as handrails were non-existent.

Not a patch on the 309s though. They were superb for commuters.

 

[physics34]

Surely the 312s were just updated (rather than souped-up) 310s. The 310s were designed for the London outer suburban services when the WCML electrification reached Euston. Previously, a few of the NW class 304s covered, but they were 75mph stock so were difficult to accomodate with LHCS stock paths. The 310s had an acceleration rate of 1.1mph/s/s to a 90mph max, which was a compromise between the 1.3-1.4mph/s/s of the 304s and the typical 0.8mph/s/s of a class 81-86 + 9 express.
When the GE services were expanded in the mid '70s there was a need to interleave the outers with the Clactons and the class 47 + 9 Norwich expresses. The speeds between Shenfield and London weren't an issue for the 75mph stock but beyond Shenfield, there was plenty of class 309 and Class 47 LHCS running at speeeds up to 100mph. The 310/312 design's 90mph with 1.1mph/s/s was a good compromise for running in with the class 309s which typically in a 2+4+4 set could attain 0.9mph/s/s on their way to 100mph.*
The main difference between the two types was that by the time the 312s were made, the safety rules meant that flat widscreens replaced the wrap-around ones originally put on the 310s.

* In the '60s when the 309s were introduced, the service between Shenfield and Chelmsford at under 8 minutes start to stop for the 9.5 miles was the fastest in the world. A clear indicator of the gains brought by 25kV electrification.
--- old post above --- --- new post below ---


Other than when they started extending the 2-car 309/1s with ex-DMU and LHCS coaches, I've never seen a 309 coupled to anything but other 309s. They were quite conventional EMUs with GEC DC motors fed from transformers via rectifiers but their performance always seemed so much better than the 4-CIGs etc. as the ac power supply wasn't compromised like the 750VDC 3rd rail supply was (and still is).

On the subject of 309s I always wondered why they weren't built with a CIG style front end, considering they were Mk1s and we're also built at York works by BR. The 309 front end with or without the wrap around window is quite ugly.

 

[Peter Mugridge]

For the benefit of the younger members of the forum who might not be familiar with what a class 312 was, here is a couple of pictures from 1985:

 

[edwin_m]

I remember Modern Railways commenting at the time both classes were introduced, about how old-fashioned the 312s looked compared with the 313s.

 

[AM9]

On the subject of 309s I always wondered why they weren't built with a CIG style front end, considering they were Mk1s and we're also built at York works by BR. The 309 front end with or without the wrap around window is quite ugly.

I think exactly the opposite but accept that it is a matter of personal taste. A freshly washed maroon 309 was a splendid sight in the dull surroundings of LIverpool St and certainly became a vision of fast outer suburban electric trains. I did make many journeys from Chelmsford/Colchester to Havant with the Essex end of the journey in a 309 and the Southern bit in a CIG/BIG. The seats were better in the 309s, they were much faster and quieter, and they looked more sleek even in the BR blue/grey livery.
The CIG's ends were a softened version of the CEPs which itself wasn't much of an improvement to standard MKI LHCS.
The 309 ends were similar in style to the class 125s which also had wraparound screens. The wraparounds were also originally used on the class 303 'Blue Trains' for Glasgow. I think that outside the SR, where flat ends had been the norm for everything since the pre-war 'torpedo' EMUs, BR tried to give multiple unit end designs a look that didn't resemble a LHCS with windows cut into the end.

 

[NSEFAN]

I remember Modern Railways commenting at the time both classes were introduced, about how old-fashioned the 312s looked compared with the 313s.

As per the 310s, they do have a very 60s feel to them. I suppose the 312s were built based on a working design. BR was skint and people knew how to handle slam door trains, so if it ain't broke, don't fix it!

 

[Phil.]

Surely the 312s were just updated (rather than souped-up) 310s. The 310s were designed for the London outer suburban services when the WCML electrification reached Euston. Previously, a few of the NW class 304s covered, but they were 75mph stock so were difficult to accomodate with LHCS stock paths. The 310s had an acceleration rate of 1.1mph/s/s to a 90mph max, which was a compromise between the 1.3-1.4mph/s/s of the 304s and the typical 0.8mph/s/s of a class 81-86 + 9 express.
When the GE services were expanded in the mid '70s there was a need to interleave the outers with the Clactons and the class 47 + 9 Norwich expresses. The speeds between Shenfield and London weren't an issue for the 75mph stock but beyond Shenfield, there was plenty of class 309 and Class 47 LHCS running at speeeds up to 100mph. The 310/312 design's 90mph with 1.1mph/s/s was a good compromise for running in with the class 309s which typically in a 2+4+4 set could attain 0.9mph/s/s on their way to 100mph.*
The main difference between the two types was that by the time the 312s were made, the safety rules meant that flat widscreens replaced the wrap-around ones originally put on the 310s.

* In the '60s when the 309s were introduced, the service between Shenfield and Chelmsford at under 8 minutes start to stop for the 9.5 miles was the fastest in the world. A clear indicator of the gains brought by 25kV electrification.
--- old post above --- --- new post below ---


Other than when they started extending the 2-car 309/1s with ex-DMU and LHCS coaches, I've never seen a 309 coupled to anything but other 309s. They were quite conventional EMUs with GEC DC motors fed from transformers via rectifiers but their performance always seemed so much better than the 4-CIGs etc. as the ac power supply wasn't compromised like the 750VDC 3rd rail supply was (and still is).

We have a winner. The 312s were indeed a modern version of the 310. the big difference was that they gangwayed throughout whereas the 310s were not gangwayed between coaches two and three. When they started working the King's Cross - Roystons in 1977 the performance was eye-opening. A four (2X2) car Cravens DMU running non-stop Finsbury Park - Potters Bar on dry rails could just about touch 55. The 312s would romp up at 90.