Class 71 to class 74

[class37418stag]

Hello everyone

 

New built class 71 at BR Doncaster work and sent to southern region by few years and later sent to BR Crewe work to replace new electric-diesel engine and new roof cover old pantograph off renumber class 74

[Southernman46]

Yes you are correct - only 10 were so converted - the rest remained as Class 71's

[jonny777]

Yes, the 71s were mostly delivered via the GC. There is a video clip of one being towed by a WD 2-8-0 through Nottingham Victoria, but the pantograph has either been removed or had yet to be fitted.

[Bert Cheese]

Class 71's were wonderful machines, a typical Southern "right first time" success story, only a lack of work saw them withdrawn.

Class 74's were a rare SR mistake...the Paxman engine should have rang alarm bells before being chosen, as well as the weird early PCB/ECU boards fitted which caused more problems than they were worth...in many ways these unfortunate locos were similar to the original version of the class 50's regarding primitive electronic control systems.

Edited April 27, 2017 by Bert Cheese

[Mike Storey]

Class 71's were wonderful machines, a typical Southern "right first time" success story, only a lack of work saw them withdrawn.

Class 74's were a rare SR mistake...the Paxman engine should have rang alarm bells before being chosen, as well as the weird early PCB/ECU boards fitted which caused more problems than they were worth...in many ways these unfortunate locos were similar to the original version of the class 50's regarding primitive electronic control systems.

 

True, of the 74.....but I still want DJM to produce one!

[Bert Cheese]

True, of the 74.....but I still want DJM to produce one!

Me too...awful rubbish but truly fascinating, I crawled over scrappers at Eastleigh years ago and became hooked...have had a weathered 74010 on pre-order since day one basically

[SRman]

Although not so apparent from the outside, the rebuild was rather more extensive than just covering over the roof well for the pantograph. The sides were completely rebuilt to become structural, load-bearing members, and the grilles and windows were differently arranged.

[Gwiwer]

The 74s were only ever considered necessary because Bournemouth line electrification would still require haulage for short distances at slow speeds beyond the "juice" in Southampton Docks.  Weymouth wasn't electrified at the time so boat trains to the Quay there were usually diesel-hauled throughout.  The low power of a 74 on diesel meant that load 11, the typical boat train, was really beyond its capability especially on Bincombe and Parkstone banks and a failure would have blocked the main line for some time.  I believe a few did reach Weymouth Quay but were unpopular with crews to put it mildly; any which were rostered were usually replaced by a 33 at Bournemouth.

 

In the event the unreliability of the 74s saw them often replaced by diesel class 33 locos on Southampton boat trains.  They did occasionally escape onto top-link work however as they have been recorded running with 2x4TC and with 4+4+3TC when a 4Rep unit has not been available. Despite reports of them being "lively" and several authenticated maxima above 100mph (against a 90mph line and loco limit) their 2300hp continuous rating was far inferior to a 4Rep at 3200hp so moving an 11-car boat or TC-stock train would have required slow starts and potential time loss.  The 15.30 Waterloo - Weymouth was a booked class 74 turn as far as Bournemouth for some time.

[Southernman46]

For me, the iconic train for 74's was that huge train of empty parcels vans that would turn up from the west at Clapham Jn about 11:30ish

[jim.snowdon]

Despite reports of them being "lively" and several authenticated maxima above 100mph (against a 90mph line and loco limit) their 2300hp continuous rating was far inferior to a 4Rep at 3200hp so moving an 11-car boat or TC-stock train would have required slow starts and potential time loss.

What matters more in this context is their short-term rating (usually quoted as the one hour rating), which will be significantly higher than the continuous, although probably by different proportions for the two motors, which were of distinctly different sizes. Plus, it is quite likely that the locomotive's controls allowed the driver more flexibility than the simple Shunt/Series/Parallel of the EMU controller.

 

Jim

[DavidB]

There are lots of interesting snippets about the 74s in Diesel and Electric Locomotives of the Southern Region, by Pallant and Bird.  Well worth a read if you can find a copy.  It includes such gems as E6108 taking a rail tour special up the remains of the old Somerset and Dorset line as far as Blandford Forum in 1968; details of what went wrong with the electronics (overheating logic box crystals and a host of other things); how the change from helical to laminated springs made them so bouncy that one bounced right off the rails; a single fuel gauge that was so hard to read that they frequently ran out of fuel; multiple issues with cracked shoe arms; and problems with the starting system and how to get around it by using/abusing the preheating system.  But at their best, they were apparently "a powerful, impressive locomotive.  In fact when running light, they had the acceleration of a powerful sports car".  I used to see them running fast through Basingstoke on Ocean Liner expresses - they looked so much more impressive than a 73 or a 33.

 

David

[50A55B]

I had several trips behind 74s on the Weymouth boat trains in the early to mid 70s and still remember the lively running and acceleration surges. They always came off at Bournemouth down and on in the up direction. On one occasion on the up train we stopped just outside Waterloo and switched to diesel for the last few hundred yards.

Edited April 28, 2017 by 50A55B

[slilley]

How opportune this has come up! I am working on a history of both classes, which I am due to deliver to the publishers in June with a view to publication in or around September this year. As always I have used original source material from the National Archives at Kew ( I was there once more this afternoon), the NRM and elsewhere. Plenty of new information coming out about both types. I wont spoil things by telling you it all just yet.

 

Best wishes

 

Simon

[Mike Storey]

It would also be interesting to learn, in layman's terms, how different the 74 was/is from the Vossloh Class 88 now coming into use for DRS. Has nth generation new technology overcome the issues? Their European equivalent has only just achieved its first major sales (and that to an open access freight operator).

[adb968008]

On 28/04/2017 at 20:31, Mike Storey said:

It would also be interesting to learn, in layman's terms, how different the 74 was/is from the Vossloh Class 88 now coming into use for DRS. Has nth generation new technology overcome the issues? Their European equivalent has only just achieved its first major sales (and that to an open access freight operator).

Class 73 and class 73/9 are both “been there and done that”… 73/9’s are hearty beasts compared to 73/1’s which are distinctly pedestrian.

[jim.snowdon]

1 hour ago, adb968008 said:

Class 73 and class 73/9 are both “been there and done that”… 73/9’s are hearty beasts compared to 73/1’s which are distinctly pedestrian.

In fairness, the 73s were built as electric locomotives with a limited 'off-juice' capability for shunting and working in possessions. The 73/9s are really diesel-electric locomotives designed for working under diesel alone, with no electric traction capability.

 

[Halvarras]

I wonder if we will ever see a model of Class 74? The fact that one doesn't need to lay a third rail theoretically works in its favour, but the single livery with a simple choice of pre-TOPS (1967-74) or post-TOPS (1974-77) certainly doesn't - the first period isn't that popular and the second not hugely better. Hornby may have the running chassis already as well as the overall dimensions, but a completely new set of tooling would be required.

Perhaps after the 4DD unit KR Models may consider it, but I can't see the modelling fraternity going for Class 74s in BR green, large logo blue and Inter City liveries! But hey, what do I know?! 

 

Mention of this class always reminds me of an article by Michael Oakley years ago, where he described an incident on one of these which, so he said, was working a service and was somehow accidentally thrown into reverse - as he put it "the resulting explosion lit up most of Winchester"! At the time I had some doubt as to whether such an action was possible, but his choice of words still amuses me to this day.

[DY444]

12 hours ago, jim.snowdon said:

In fairness, the 73s were built as electric locomotives with a limited 'off-juice' capability for shunting and working in possessions. The 73/9s are really diesel-electric locomotives designed for working under diesel alone, with no electric traction capability.

 

Er, apart from the fact that they still retain their electric traction capability.  The sleeper locomotives had their shoe gear removed having been originally delivered with it fitted but still retain the electric traction innards and the Southern based 73/9s run on electric power regularly.  For instance: