A couple of questions regarding the AM10 and AM12 EMU's

Clarence Yard · 20 Jan 2022

contrex said:
Were class 312 emus ever called 'AM12' by anyone within BR? I know they were based on the emus classified AM10 in 1964/5 that were later given the TOPs class 310 designation. The AM series started in the 1950s, and as far as I know AM2 to AM11 became 302 to 311 (AM1 was withdrawn in 1966 before TOPS).

I did hear a few people refer to them as AM12 in their early days on the LM but on the GN we always called them a 312. I travelled to/from work on the AM10 fleet (and very occasionally a 304 or 312) in and out of Euston for over a decade and in my 43 years of commuting to/from Watford Junction they were my clear favourite, although a 350/2 comes close.

The drivers used to push them well beyond 75mph if it was needed and loading/unloading was swift and efficient. You never got too near the platform edge on the stations as the doors would swing open as the trains came in and people would be leaving the unit before it came to a stand. I used to do the same at Euston so I could get past the ticket collectors before the crowd behind caused a blockage at the barrier. The heating worked, the seats were comfortable and the ride was good.

DOO was the main factor in them leaving the GN. The 317 was a superior performing piece of kit but in the London area of the GN the EMU’s rarely got in the way of an HST, whether they were a 312 or 317. Personally I didn’t like the early 317 sets on the LM service out of Euston - I found them airless and claustrophobic with inferior seats. I was quite glad to see them go when we got the new “dusty bins”.

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AM9 · 20 Jan 2022

gg1 said:
Fair point, hadn't considered that.

The Chiltern 121 and Lymington 3CIGs probably had a similar ratio of doors to carriage but the odd locking failure on a relatively lightly used route isn't a major problem.

I think the CIGs were generally 6 doors per car, but if they were VEPs they would have over 60 passenger doors

Peter Mugridge · 20 Jan 2022

nw1 said:
Wasn't there a time when the LTS had about 4 different unit classes in regular service, all very different in appearance? Perhaps 302, 312, 317 and 321?

It was 302, 305, 308, 310, 312, 317 - but I think the 302s went before the 317s arrived; pretty sure both the 302s and the 317s did overlap with the middle four making five classes at once for a brief period.

nw1 · 20 Jan 2022

AM9 said:
I think the CIGs were generally 6 doors per car, but if they were VEPs they would have over 60 passenger doors

True, and VEPs were used for 35 years on the Southern on narrow-headway services.

Peter Mugridge said:
It was 302, 305, 308, 310, 312, 317 - but I think the 302s went before the 317s arrived; pretty sure both the 302s and the 317s did overlap with the middle four making five classes at once for a brief period.

Ah right - thanks. Yes now you mention it, I think I remember 310s being mentioned, but not 305 or 308.

Certainly vary varied stock for essentially a self-contained network.

pdeaves · 20 Jan 2022

gg1 said:
The Chiltern 121 and Lymington 3CIGs probably had a similar ratio of doors to carriage but the odd locking failure on a relatively lightly used route isn't a major problem.

I think the Chiltern 121 had some doors permanently fixed shut, reducing the issue. In the context of 310/312, that probably wouldn't have been practical on peak flows (if anyone would even have thought about doing that at the time).

jfollows · 20 Jan 2022

AM9 said:
I think the CIGs were generally 6 doors per car, but if they were VEPs they would have over 60 passenger doors

GS250 · 20 Jan 2022

Clarence Yard said:
I did hear a few people refer to them as AM12 in their early days on the LM but on the GN we always called them a 312. I travelled to/from work on the AM10 fleet (and very occasionally a 304 or 312) in and out of Euston for over a decade and in my 43 years of commuting to/from Watford Junction they were my clear favourite, although a 350/2 comes close.

The drivers used to push them well beyond 75mph if it was needed and loading/unloading was swift and efficient. You never got too near the platform edge on the stations as the doors would swing open as the trains came in and people would be leaving the unit before it came to a stand. I used to do the same at Euston so I could get past the ticket collectors before the crowd behind caused a blockage at the barrier. The heating worked, the seats were comfortable and the ride was good.

Being my 'local' line....this was exactly what I remember. I'm not sure if any AM10's were diagrammed to use the fast lines? I believe the 'fast' rush hour commuter services that were generally RA to to Leighton Buzzard used the fast lines to Ledburn Junction then slow onwards. These were usually in the hands of 'cobbler' sets of 10 Mk1s and more often than not an AL5, occasionally an AL6. Pretty sure these were timed at 100mph to Ledburn. However, when the AM10's did find themselves on the fast line, yes I remember peering into the cab area from behind and seeing the needle raise well into the 80s.

notadriver · 20 Jan 2022

Magdalia said:
I have a lot of experience of the class 312s on the GN. They were not very fast when compared to what followed. A train not stopping at Finsbury Park would do well to make more than 80mph on the climb to Potters Bar. I don't remember signal checks when following HSTs, but I do remember the class 312s filling up with HST fumes in the tunnels. The problem was more the class 312s delaying the HSTs, which is why they were replaced with class 317s.

In my opinion a balancing speed of 80 mph for the class 312 on the 1 in 200 climb to Potters Bar was an excellent effort for the time. The typical slam door EMU of the time like a 4CEP could barely exceed 80 mph on level track. Obviously HSTs are faster on the climb but a class 47 hauling 8 coaches or Deltic + 11 coaches would manage a similar speed on the climb.

I think the class 317s power output is somewhat understated - I reckon it’s good for nearer 1500 hp a set explaining its fantastic 0-60 time of just over 50 seconds coupled with fantastic 90 mph climb performance on the 1 in 200 to Potters Bar.

I also remember enjoying a view out the front of a class 310 leaving Euston. These are rated to 75 mph but the driver left the power controller open and despite the climb towards Watford I recall the speed being well into the low 80s. Great times.

AM9 · 20 Jan 2022

Clarence Yard said:
I did hear a few people refer to them as AM12 in their early days on the LM but on the GN we always called them a 312. I travelled to/from work on the AM10 fleet (and very occasionally a 304 or 312) in and out of Euston for over a decade and in my 43 years of commuting to/from Watford Junction they were my clear favourite, although a 350/2 comes close. ...

They came to the GE I think in 1975, by which time I'd moved to Billericay and was then only commuting on 306s and 305/307/308s. I do remember when they were announced, (in enthusiasts' conversations they became known as '12s), that they were to supplement the 309s allowing intermediate services to be upgraded from non-corridor units. Colchester from Liverpool St was a bit gruelling in a 305/308, so the 312 journey would have been more comfortable. I think that they were fine running the Shenfield and all stops to Colchester as their acceleration was much better than a 47+11 and slightly better than a 309.

Strathclyder · 20 Jan 2022

Magdalia said:
Hertfordshire ran two "Grand Slam" railtours with class 312s on 06/03/04 and 13/03/04, see Six Bells for details.

Class 313s managed almost 43 years on the GN. Class 317s are about 40 years old, depending on what you count as their start date.

That they did, here are the Six Bells reports for both:

Six Bells Junction

www.sixbellsjunction.co.uk

Six Bells Junction

www.sixbellsjunction.co.uk

I've always alternated between when a given unit was first built and when it entered service. Both are correct in their own way, I suppose.

GS250 said:
I'd almost certainly suggest that 312 unit at Euston was a 'football special' from the North. August would have been the 'Charity Shield' between Everton and Manchester United.

I see, certainly computes. Cheers.

AM9 said:
Central door locking on an outer suburban EMU would make peak services a hostage to fortune that one of the 46 slam doors on a 4-car unit might fail. Given that most outer suburban peak services on the GEML are 12-car, that's 138 retro-fitted mechanisms just waiting for their moment to fail. Dwells on peak services on the GEML are just too critical to risk that.
It's different on normal corridor express stock where there are four per car at the ends where most commuters would abort an attempt and slip through the vestibile to the next car.

JonathanH said:
The last 312s on the GE had some doors locked up in the last few years. As much as anything, I suspect a desire to run more services DOO was another reason for their withdrawal.

Hadn't considered these points, makes sense.

GS250 · 20 Jan 2022

notadriver said:
In my opinion a balancing speed of 80 mph for the class 312 on the 1 in 200 climb to Potters Bar was an excellent effort for the time. The typical slam door EMU of the time like a 4CEP could barely exceed 80 mph on level track. Obviously HSTs are faster on the climb but a class 47 hauling 8 coaches or Deltic + 11 coaches would manage a similar speed on the climb.

I think the class 317s power output is somewhat understated - I reckon it’s good for nearer 1500 up a set explaining its fantastic 0-60 time of just over 50 seconds coupled with fantastic 90 mph climb performance on the 1 in 200 to Potters Bar.

I also remember enjoying a view out the front of a class 310 leaving Euston. These are rated to 75 mph but the driver left the power controller open and despite the climb towards Watford I recall the speed being well into the low 80s. Great times.

I'm sure the 312s were a huge improvement performance wise over what they replaced. I believe this was the Class 31's and suburban stock? I'd like to know what their balancing speed up to Potters Bar was. Saying that...I remember a mid 80s copy of Modern Railways Pictorial claiming a 31 plus load 10 of mk1s could do Kings X - Peterborough in an hour with one stop at Huntingdon.

Clarence Yard · 20 Jan 2022

I haven’t got all my old WTT’s to hand but I know a 31 on an 8 coach Mk1 set (load D280) going to Peterborough was timetabled to cover KX to Potters Bar in 16.5 minutes (start to pass), which was fairly easy to achieve.

notadriver · 20 Jan 2022

Clarence Yard said:
I haven’t got all my old WTT’s to hand but I know a 31 on an 8 coach Mk1 set (load D280) going to Peterborough was timetabled to cover KX to Potters Bar in 16.5 minutes (start to pass), which was fairly easy to achieve.

I bet thats slower than steam - 1100 rail horse power for a total loco+train weight of 380 tons is hard going. I bet 55 mph at Potters Bar.

A0wen · 20 Jan 2022

GS250 said:
I'm sure the 312s were a huge improvement performance wise over what they replaced. I believe this was the Class 31's and suburban stock? I'd like to know what their balancing speed up to Potters Bar was. Saying that...I remember a mid 80s copy of Modern Railways Pictorial claiming a 31 plus load 10 of mk1s could do Kings X - Peterborough in an hour with one stop at Huntingdon.

It was a mix of Cravens 105 DMUs, Derby 116 DMUs and 31s with suburban stock on the GN for the outer suburbans.

The inner suburbans were Class 125 Hydraulic DMUs - these went for scrap when the 313s arrived, the other DMUs were cascaded elsewhere.

Magdalia · 20 Jan 2022

notadriver said:
I bet thats slower than steam - 1100 rail horse power for a total loco+train weight of 380 tons is hard going. I bet 55 mph at Potters Bar.

Depends on what sort of steam! 55 mph is a good calculation, from my experience I would have said 57 mph. Either way, the last stage of field diversion did not happen until after Potters Bar.

A0wen said:
It was a mix of Cravens 105 DMUs, Derby 116 DMUs and 31s with suburban stock on the GN for the outer suburbans.

The inner suburbans were Class 125 Hydraulic DMUs - these went for scrap when the 313s arrived, the other DMUs were cascaded elsewhere.

It was a bit more complicated than that. Most Moorgate trains were class 31 on load 6 blockenders, most Broad Street trains were the Rolls Royce hydraulic DMUs. Outer suburban trains were mostly load 8 Mark Is just like the Peterboroughs in the 1980s.

Each of those categories also had some blue square DMU trains, 2 or more motor plus trailer Craven twins or 3 car Derby suburbans. I did once have a 4 car Cravens out of Kings Cross: I don't now the speed but I do remember the noise, the rattling and the fumes in the single bore tunnels.

A 6 car Rolls Royce hydraulic DMU had 1900 hp to play with so would probably have been quite swift if given the chance.

But class 312s were a step forward from all of these!

A0wen · 20 Jan 2022

Magdalia said:
Depends on what sort of steam! 55 mph is a good calculation, from my experience I would have said 57 mph. Either way, the last stage of field diversion did not happen until after Potters Bar.

It was a bit more complicated than that. Most Moorgate trains were class 31 on load 6 blockenders, most Broad Street trains were the Rolls Royce hydraulic DMUs. Outer suburban trains were mostly load 8 Mark Is just like the Peterboroughs in the 1980s.

Each of those categories also had some blue square DMU trains, 2 or more motor plus trailer Craven twins or 3 car Derby suburbans. I did once have a 4 car Cravens out of Kings Cross: I don't now the speed but I do remember the noise, the rattling and the fumes in the single bore tunnels.

A 6 car Rolls Royce hydraulic DMU had 1900 hp to play with so would probably have been quite swift if given the chance.

But class 312s were a step forward from all of these!

There are plenty of photos of Cravens DMUs at Moorgate and indeed of them on services to Huntingdon, Baldock and Royston among others.

The book Kings Cross Lineside 1958-1984 by David Percival covers most of this in detail.

Peter Mugridge · 20 Jan 2022

nw1 said:
Ah right - thanks. Yes now you mention it, I think I remember 310s being mentioned, but not 305 or 308.

Certainly vary varied stock for essentially a self-contained network.

Here's one of each, all on the same day.

Bishopstone · 21 Jan 2022

Peter Mugridge said:
It was 302, 305, 308, 310, 312, 317 - but I think the 302s went before the 317s arrived; pretty sure both the 302s and the 317s did overlap with the middle four making five classes at once for a brief period.

My memory is that 302s overlapped with 317s on LTS, but by this time the 305s and 308s had gone. So the run-out for a year or so was 302, 310, 312, 317.

Concerning 310s, I remember the appearance of some cascaded 3-car units on LTS, in a derivation of Regional Railways livery. I recall this was an emergency measure connected with delays to the introduction of the 357s.

Magdalia · 21 Jan 2022

A0wen said:
There are plenty of photos of Cravens DMUs at Moorgate and indeed of them on services to Huntingdon, Baldock and Royston among others.

The book Kings Cross Lineside 1958-1984 by David Percival covers most of this in detail.

Absolutely. David Percival's book is essential reading for anyone interested in this corner of railway history. The Cravens sets worked through to and from Cambridge on off peak trains to provide moves for maintenance purposes. Although allocated to Finsbury Park most of the maintenance on the GN Cravens sets was done at Cambridge.

Alfie1014 · 22 Jan 2022

Bishopstone said:
My memory is that 302s overlapped with 317s on LTS, but by this time the 305s and 308s had gone. So the run-out for a year or so was 302, 310, 312, 317.

Concerning 310s, I remember the appearance of some cascaded 3-car units on LTS, in a derivation of Regional Railways livery. I recall this was an emergency measure connected with delays to the introduction of the 357s.

It was earlier than that, in 1992 when the LTS was suffering from ‘exploding‘ brakevans, the 357s didn’t come on the scene until 1999. Basically it was failure of the high tension cables between the pantograph and transformer resulted in failures in service causing some hairy experiences for some guards who were in the guards brakes at the time, (brake Van doors being blown off!) It happened to at least one 308 and a 312. Upon investigation, (and I’m by no means an expert so relying on my memory here), it was found that the oil had become contaminated causing the insulation to fail. Samples were sent off to the BR laboratories for testing from all the ac fleets and as a result some whole sets were withdrawn from traffic, whilst some simply had their brake coaches locked out of use with guards performing their duties from cabs. As the oil (and cables?) were replaced sets were reintroduced back into traffic or had the accommodation in motor coaches returned to use. This resulted in a shortage of stock for many months with an introduction of an emergency reduced timetable and as a result almost any ac EMU stock cleared for operation on the LTS was used, including Regional Railways 3 car 310s, 305s from NE London services. I just wish I had taken more photographs at the time of the lash ups that operated!

Bikeman78 · 20 Mar 2022

Peter Mugridge said:
It was 302, 305, 308, 310, 312, 317 - but I think the 302s went before the 317s arrived; pretty sure both the 302s and the 317s did overlap with the middle four making five classes at once for a brief period.

My first ride on the LTS was in 1995. By then it was all class 302, 310 or 312. The 302s and 317s overlapped for a few months. On the class 302 farewell day in July 1998, most trains were single class 317s, alongside the three sets of 302s that were running.

Alfie1014 said:
It was earlier than that, in 1992 when the LTS was suffering from ‘exploding‘ brakevans, the 357s didn’t come on the scene until 1999.

The three car 310s went back to the LTS in 2000 for about a year to cover for the class 357s. I had a ride on 11 of them. 310103 was long gone; not sure if 310106 went to the LTS.

The same period saw three pairs of class 317s hired from WAGN every day. The resident class 317s had gone by then.

Big Jumby 74 · 20 Mar 2022

AM9 said:
Colchester from Liverpool St was a bit gruelling in a 305/308, so the 312 journey would have been more comfortable. I think that they were fine running the Shenfield and all stops to Colchester as their acceleration was much better than a 47+11 and slightly better than a 309

I had a period back in 1980 or so of spending time in Chelmsford and was in the habit of 'commuting' up to Liv Street late evening. Always felt the 312's once up to speed, felt like they were shifting somewhat, but may have been a slight elusion as it was always dark at the time I travelled. Do have a fond spot for them and the AM10's, may be partly because they had a modern cab front style compared, relatively speaking, to our Southern 400 series units at the time.

Merle Haggard · 20 Mar 2022

The 312s were definitely used on service trains into Euston.

One of the differences was that the AM12s were gangway throughout whereas the AM10s only had gangways between the driving train and the adjacent intermediate coach, with the guard's compartment having no access from the passenger saloon.

On one occasion travelling to Euston on an AM12 I walked the length of the train; walking past his compartment, the guard's body language suggested had had taken great offence at anyone being able to see him at work.

AM9 · 20 Mar 2022

Merle Haggard said:
The 312s were definitely used on service trains into Euston.

One of the differences was that the AM12s were gangway throughout whereas the AM10s only had gangways between the driving train and the adjacent intermediate coach, with the guard's compartment having no access from the passenger saloon.

On one occasion travelling to Euston on an AM12 I walked the length of the train; walking past his compartment, the guard's body language suggested had had taken great offence at anyone being able to see him at work.

Probably didn't want any passengers to know what he was/wasn't doing.

Ken H · 20 Mar 2022

What was the difference between 310 and 312? I suppose what I am really asking is why 312 weren't designated 310/2?

Standing on the platform i dont think most non rail nuts would know the difference.

AM9 · 20 Mar 2022

Ken H said:
What was the difference between 310 and 312? I suppose what I am really asking is why 312 weren't designated 310/2?

Standing on the platform i dont think most non rail nuts would know the difference.

Much the same as 320, 321 and 322, or the earlier 304, 305 & 308 classes. It still goes on, - there's 196 & 197s, 377's and 378s.

GC class B1 · 20 Mar 2022

Ken H said:
What was the difference between 310 and 312? I suppose what I am really asking is why 312 weren't designated 310/2?

Standing on the platform i dont think most non rail nuts would know the difference.

Class 310 had B4 and B5 bogies without primary dampers and as a result were 75 MPH maximum speed. Class 312 had B4 and B5 bogies with friction primary dampers and were 100 MPH maximum speed.

306024 · 20 Mar 2022

GC class B1 said:
Class 310 had B4 and B5 bogies without primary dampers and as a result were 75 MPH maximum speed. Class 312 had B4 and B5 bogies with friction primary dampers and were 100 MPH maximum speed.

Where did they operate at 100 mph? My recollection is that they were 90 mph top speed, certainly on the Great Eastern.

GC class B1 · 20 Mar 2022

306024 said:
Where did they operate at 100 mph? My recollection is that they were 90 mph top speed, certainly on the Great Eastern.

They may have been 90 MPH max on WCML, I cannot remember but B4 bogies with primary dampers are 100 MPH.

Snow1964 · 20 Mar 2022

Merle Haggard said:
The 312s were definitely used on service trains into Euston.

One of the differences was that the AM12s were gangway throughout whereas the AM10s only had gangways between the driving train and the adjacent intermediate coach, with the guard's compartment having no access from the passenger saloon.

On one occasion travelling to Euston on an AM12 I walked the length of the train; walking past his compartment, the guard's body language suggested had had taken great offence at anyone being able to see him at work.

There was only 4 312s on WCML, working alongside the 310s which had been built for service enhancements in the West Midlands, and these occasionally found their way to Euston. The Kings Cross and Great Eastern sets never appeared on Euston-West Midlands (there was no electrified connection in 1980s)

I was at University in Coventry in mid 1980s and most local services were 310s, with the 312s occasionally appearing (and the dreadfully bouncy 304s occasionally being used instead). Even when two units were coupled I don’t ever remember any mixed formations (where the different classes even permitted to couple on WCML)

The GE sets were initially dual voltage, as 6.25kv was used inwards from Shenfield, it was converted in phases by 1981 (Bethnal Green- Clapton area was converted about 1983 and the new 315s couldn’t use the line until converted) The 312s GE batch were last trains built which had 6.25kv capability.

My recollection is that the 310s stayed on Euston lines until 321s arrived, but the GN 312 batch were replaced by 317s displaced from St Pancras services by new 319s from 1987 onwards. In turn the 312s moved to GE which by then was struggling with stock following the opening of electrification to Manningtree, and electrification extensions to Cambridge, and the asbestos withdrawal deadline.

My memory says the 312s had a 90mph top speed, although those on the West Midlands might have been 75mph.

A couple of questions regarding the AM10 and AM12 EMU's

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