Why was the Class 45 kept in service over the Class 40?

[Sun Chariot]

The class 40s that were repurposed for pw use with Crewe station area's remodelling. Other than being renumbered to 974xx series, did they receive any modification? I don't recall mention of any such, in the railway press of the time

Tinsley's 45s that were renumbered into the 974xx series: what duties were they repurposed for? Was it general pw duties, or something more specific?

 

[AndrewE]

47s can be opened to full power straightaway with the only potential issue being rail conditions, the locos themselves can take it.

that is interesting, and might be unusual. I remember a few footplate rides on diesels, probably Peaks and 37s, (mostly officially when I was working!) and some on electric locos too.
I think the drivers explained that they couldn't be "notched up" further until the current had dropped back due to the rising back-EMF from the traction motors.

It's why I believe that steam locos can exert full tractive effort on starting but diesels (and electrics) can't as you would burn out the traction motors. Hence huge slow steam freights grinding along at walking pace using the full boiler output, whereas [oldish] replacement higher tech kit can't actually exploit its nominal HP until it gets up to much higher speeds.

 

[Gloster]

The class 40s that were repurppsed for pw use with Crewe station area's remodelling. Other than being renumbered to 974xx series, did they receive any modification? I don't recall mention of any such, in the railway press of the time

Tinsley's 45s that were renumbered into the 974xx series: what duties were they repurposed for? Was it general pw duties, or something more specific?

I have looked at various sources. Four 46 went went to Derby RTC: one for a sudden end, a second (I think) as its reserve, and two others, one for spares, for other work. Five 45 became 97409-97413 to release 31 from wiring trains north of Newcastle.

EDIT: according to Wikipedia the Crewe 40s were restricted to 35 mph.

 

[hexagon789]

The class 40s that were repurppsed for use with Crewe station area's remodelling. Other than being renumbered to 974xx series, did they receive any modification? I don't recall mention of any such, jn the rail press of the time

Tinsley's 45s that were renumbered into the 974xx series: what duties were they repurposed for?

The four ex-40s were restricted (by notice, no physical modifications) to 35mph for use on engineering trains, such as ballast trains

The two ex-46s were used on wheelslip test rig trains.

The five ex-45s were for various infrastructure trains.

that is interesting, and might be unusual. I remember a few footplate rides on diesels, probably Peaks and 37s, (mostly officially when I was working!) and some on electric locos too.
I think the drivers explained that they couldn't be "notched up" further until the current had dropped back due to the rising back-EMF from the traction motors.

It's why I believe that steam locos can exert full tractive effort on starting but diesels (and electrics) can't as you would burn out the traction motors. Hence huge slow steam freights grinding along at walking pace using the full boiler output, whereas [oldish] replacement higher tech kit can't actually exploit its nominal HP until it gets up to much higher speeds.

Most diesel electrics can, if the equipment is suitable, be opened fully from a stand. Indeed if you ever get the chance to look at BR traction manuals, that is generally the given technique.

Certainly 50s were also designed to start on full power, but as built had a more advanced wheelslip protection system and a current limiting control. Both features were removed at refurbishment.

Deltics were a notable exception, perhaps because of their very high power-to-weight ratio, full power below about 25-30mph seems to have always produced wheelspin on that class.

 

[edwin_m]

I think the drivers explained that they couldn't be "notched up" further until the current had dropped back due to the rising back-EMF from the traction motors.

It's why I believe that steam locos can exert full tractive effort on starting but diesels (and electrics) can't as you would burn out the traction motors. Hence huge slow steam freights grinding along at walking pace using the full boiler output, whereas [oldish] replacement higher tech kit can't actually exploit its nominal HP until it gets up to much higher speeds.

That behaviour is inherent to electric motors, but I guess some locos have control systems that compensate automatically (as traditional DC EMUs do by "notching up" the camshaft). But if a steam engine was given full power from a standstill then it would spin the wheels too. Power equals force (tractive effort) times speed, so if a lot of power is applied at low speed then a very large force will be exerted and this will exceed the available friction between the wheels and rails.

 

[Sun Chariot]

Thanks @Gloster and @hexagon789
Yes, I'd recalled the restricted speed limit on 974xx 40s and 45s was not a mod per se.
Yes, 97403 (46035) "Ixion" popped up at so many open days in latter 1980s. 97404 (46045) was a rarer beast. I photo'd it forlorn outside Derby.

OT, I also photo'd 97202 (25131) amongst Crewe's withdrawn Rats, May 1986.
46009's moment of infamy made national TV evening news. Footage was also shown at BNFL Heysham when I visited in 1989, as part of a uni organised visit.

 

[Trackman]

The four ex-40s were restricted (by notice, no physical modifications) to 35mph for use on engineering trains, such as ballast trains

I think it was something to do with tyre wear as most of them didn't have much left. A bit like the class 81's (?? I think) doing ECS duties at Euston.

I think 40009 was the last surviving vac only Whistler.

It was, mind-boggling how she lasted so long.
Cabbed it once, was astonished it had a clasp vacuum brake handle rather than the 'modern' shipped 1960's ones.

 

[AndrewE]

That behaviour is inherent to electric motors, but I guess some locos have control systems that compensate automatically (as traditional DC EMUs do by "notching up" the camshaft). But if a steam engine was given full power from a standstill then it would spin the wheels too. Power equals force (tractive effort) times speed, so if a lot of power is applied at low speed then a very large force will be exerted and this will exceed the available friction between the wheels and rails.

yea, but you can open the regulator gently and when you are just moving open it a lot more. Without the back-emf you can't do that with diesel-electric for a long time. My copy of "Nine Elms Engineman (which i really recommend) describes a particular freight train which was worked "full-out" - full regulator and 0% (or is that 100%) cut-off.

 

[hexagon789]

I think it was something to do with tyre wear as most of them didn't have much left. A bit like the class 81's (?? I think) doing ECS duties at Euston.

That would make sense, no sense replacing the tyres if you can get away with a speed restriction and eke it out a bit.

 

[edwin_m]

Yes, 97403 (46035) "Ixion" popped up at so many open days in latter 1980s.

It had one traction motor disconnected from the rest, which could be spun individually to measure wheel-rail friction.

 

[Cowley]

That would make sense, no sense replacing the tyres if you can get away with a speed restriction and eke it out a bit.

I think those four class 40s renumbered as 97s certainly rescued the odd failed train from what I remember and I’ve got a feeling that they might have appeared on the odd local parcels train too?

Not saying that they exceeded 35mph but I guess it was possible if the only thing stopping that was a label next to the speedo?

 

[hexagon789]

I think those four class 40s renumbered as 97s certainly rescued the odd failed train from what I remember and I’ve got a feeling that they might have appeared on the odd local parcels train too?

Not saying that they exceeded 35mph but I guess it was possible if the only thing stopping that was a label next to the speedo?

Yep, that's exactly what I meant by 'restricted by notice'.

 

[Sun Chariot]

I think those four class 40s renumbered as 97s certainly rescued the odd failed train from what I remember and I’ve got a feeling that they might have appeared on the odd local parcels train too?

My grey cells think Rail Enthusiast made mention of 'Andania' or 'Aureol' on a revenue earning service.

I think it was something to do with tyre wear as most of them didn't have much left. A bit like the class 81's (?? I think) doing ECS duties at Euston.

The two 82s and two (or was it three) 83s, I well remember and have photos of them. I remeber the 81s on freight services; I can't remember them on Euston-Wembley ECSs.

 

[The Crab]

For me, same as 20s 37s & 50s, those wonderful EE sounds. Lower power was never a problem for me as a basher, you got full thrash for longer.

The EE4’s low power was probably why drivers in some places called 47s a ‘4 and a half’, although many drivers much preferred a ‘Crompton’ (45) over a 47 not least because of draughts.

I don't remember "4 and a half" but we used to call the EE4s "3 and a half".

 

[Helvellyn]

I think those four class 40s renumbered as 97s certainly rescued the odd failed train from what I remember and I’ve got a feeling that they might have appeared on the odd local parcels train too?

Not saying that they exceeded 35mph but I guess it was possible if the only thing stopping that was a label next to the speedo?

The speed restriction was possibly in part to stop Control nabbing them and sticking them on a working in an emergency - "No problem, I sign the North Wales route so can take Whistler to Holyhead"

The two 82s and two (or was it three) 83s, I well remember and have photos of them. I remeber the 81s on freight services; I can't remember them on Euston-Wembley ECSs.

It was extremely shortlived either just as push-pull working was being implemented, or just after, that a couple of 81s made their way down from Scotland for ECS duties. (It also was three 83s)

 

[Indigo Soup]

Watching, first, a Pacific romp effortlessly (ok, the fireman was puttiing in some effort!) past on 16 by followed by an EE4 on 11, full power thrashing away and grinding past at half the speed. Initially, the EE4s only took over 6P and 7P steam diagrams, the 8P ones were beyond them.

Remember that the LMS Twins were supposed to work singly on 5MT duties, or as a pair on 8P duties.

I've heard the theory that BR forgot to allow for loss of power between the engine and the rail when drawing up the power classes, which is why all the early diesels wound up being underpowered for their intended uses.

Hence huge slow steam freights grinding along at walking pace using the full boiler output, whereas [oldish] replacement higher tech kit can't actually exploit its nominal HP until it gets up to much higher speeds.

AFAIK, the general rule of thumb is that diesels are limited by tractive effort, and steam locos by boiler capacity.

The result is that a steam locomotive can start anything that it can pull at speed, whereas a diesel can pull at speed anything that it can start.

 

[Sun Chariot]

It was extremely shortlived either just as push-pull working was being implemented, or just after, that a couple of 81s made their way down from Scotland for ECS duties. (It also was three 83s

Thanks for confirming re: three 83s (I have photos of the three but one wasn't doing an ECS turn, so I couldn't recall if it was in that same pool).
Ah, the 81s were probably being used while I Iived in Preston for a short while.

 

[AndrewE]

AFAIK, the general rule of thumb is that diesels are limited by tractive effort, and steam locos by boiler capacity.

The result is that a steam locomotive can start anything that it can pull at speed, whereas a diesel can pull at speed anything that it can start.

that is very good, apart from Cl 66s! The Tractive Effort curve collapses at about 25mph, so they can't pull what they can start at speed! I heard a lecturer say it was one of the main justifications for the Cl 99: they could keep a freight train up to speed on Shap and Beattock, making more paths available and presumably at a lower price if you can flight 3 freights in the path a Cl 66 would need.

 

[edwin_m]

that is very good, apart from Cl 66s! The Tractive Effort curve collapses at about 25mph, so they can't pull what they can start at speed! I heard a lecturer say it was one of the main justifications for the Cl 99: they could keep a freight train up to speed on Shap and Beattock, making more paths available and presumably at a lower price if you can flight 3 freights in the path a Cl 66 would need.

As I mentioned earlier, power equals tractive effort multiplied by speed.

Maximum tractive effort occurs at very low speeds where power isn't an issue. It depends on the amount of weight on the powered wheels (so 40s, 45s and 46s as well as most steam locos lost some due to the carrying wheels), and on the coefficient of friction between the wheel and the rail. The Class 66 and other modern locomotives have creep control systems that can effectively improve the coefficient of friction, so have more tractive effort for their weight than older types.

However, as speed increases, the power needed to keep moving will also increase and at some point maximum power will be reached. After this the available tractive effort will fall, and rolling and air resistance also increase so acceleration falls off even more. Electrics can have much more power available from the wire than diesels that have to generate their power on board, so electrics will generally have much better performance in the higher speed ranges. More recent electrics with three-phase AC motors are better still at higher speeds because they avoid the reduction in tractive effort of a DC motor when it turns faster.

 

[Justin Smith]

Class 46’was a Brush product. They supplied 500+ locos needing derating to survive and 300+ locos needing replacement EE power units to survive. NBL ought to glow by comparison.

To be fair to Brush it was the Sulzer engine that was the "problem". Though BR did actually discover what could be done to improve the reliability of the block (when uprated to give 2750BHP) but by then decided it was not worth yet another modification and the downrating may well still help long term reliability.

 

[thedbdiboy]

It was extremely shortlived either just as push-pull working was being implemented, or just after, that a couple of 81s made their way down from Scotland for ECS duties. (It also was three 83s)

The ECS 82s/83s lasted a few years. The fleets were originally stored between 1982 and 1983 but 83012, 82005 and 82008 were in working condition and quickly found use on the ECS duties. 83015 had been stored at Croxley Green depot, and before long also got reactivated and pressed back into use. 83009 was used for load bank duties at Longsight but after a while that one too was sent south and the fleet of 5 oddballs worked until around 1988 if I recall, until the 86s/87s gained TDM equipment and the Mk1 BGS were replaced with DVTs removing the need for any shunt releasing of stock.

 

[xotGD]

The ECS 82s/83s lasted a few years. The fleets were originally stored between 1982 and 1983 but 83012, 82005 and 82008 were in working condition and quickly found use on the ECS duties. 83015 had been stored at Croxley Green depot, and before long also got reactivated and pressed back into use. 83009 was used for load bank duties at Longsight but after a while that one too was sent south and the fleet of 5 oddballs worked until around 1988 if I recall, until the 86s/87s gained TDM equipment and the Mk1 BGS were replaced with DVTs removing the need for any shunt releasing of stock.

Weren't one or two also used for ecs duties at Manchester Pic?

 

[43096]

Weren't one or two also used for ecs duties at Manchester Pic?

There was an 85 that was later used for Manchester Picc-Longsight stock moves - would have been about the same time as the 82s/83s were replaced at the London end by 81s and 85s.

 

[Trackman]

The ECS 82s/83s lasted a few years. The fleets were originally stored between 1982 and 1983 but 83012, 82005 and 82008 were in working condition and quickly found use on the ECS duties. 83015 had been stored at Croxley Green depot, and before long also got reactivated and pressed back into use. 83009 was used for load bank duties at Longsight but after a while that one too was sent south and the fleet of 5 oddballs worked until around 1988 if I recall, until the 86s/87s gained TDM equipment and the Mk1 BGS were replaced with DVTs removing the need for any shunt releasing of stock.

Don't think 83009 was ever used as a load bank, but it was a static DC convertor for the Hadfield units.

 

[thedbdiboy]

Don't think 83009 was ever used as a load bank, but it was a static DC convertor for the Hadfield units.

Yes, you're right, I got it's role mixed up with 84009!

 

[61653 HTAFC]

99.5% correct. D255 was briefly fitted with experimental ETH.

Speaking of 40s and ETH, when 40145 had it's first spell in (inauthentic) Large Logo livery in the 1990s, it carried the number 40445- which could give the false impression that it was fitted with Electric Train Heating!

 

[Cowley]

There’s a new new thread on the differences between classes providing ETH/ETS for coaching stock here now:

The effect of ETH-AirCon on locomotive performance, with an emphasis on classes 33, 47/4, 50 and 52.

There's been reference to the greater installed horsepower of 47s over 40s and the advantage of the former in also having ETH; but didn't ETH reduce the drawbar horsepower available? mods note - split from this thread...

www.railforums.co.uk

 

[70014IronDuke]

99.5% correct. D255 was briefly fitted with experimental ETH.

Sticking very much on topic to the OP's question - what do we know about this? How was the ETH supplied? When was it? Are there any reports from back in the day as to what the results were?

Presumably someone had a think about this and decided that drawing off c 400 hp from an already underpowered 138 ton 1Co-Co1 loco with a max speed of 90 mph was not good economics by 1970.

 

[hexagon789]

Sticking very much on topic to the OP's question - what do we know about this? How was the ETH supplied? When was it? Are there any reports from back in the day as to what the results were?

Presumably someone had a think about this and decided that drawing off c 400 hp from an already underpowered 138 ton 1Co-Co1 loco with a max speed of 90 mph was not good economics by 1970.

Lion was specifically specified as 2,750hp and not 2,300hp (as per the 44s, which were the mechanical basis for the design) to account for ETH load.

I did see a short piece on the 40 with ETH from new, but I've forgotten where. Hopefully I might have saved the link somewhere.

 

[matchmaker]

To be fair to Brush it was the Sulzer engine that was the "problem". Though BR did actually discover what could be done to improve the reliability of the block (when uprated to give 2750BHP) but by then decided it was not worth yet another modification and the downrating may well still help long term reliability.

The derated locos were of course the 47s, not the 46s.