Most Unreliable Locomotive

[Tynwald]

Nothing was perfect, and most classes had there achillies heel. NBL stuff was very bad post steam. The MAN engines and Voith transmissions they made under license were dreadful. Paxman engines pretty poor (even in HST's). EE stuff was maybe the best, but Class 40 bogies, and Class 50 load control/generators were troublesome. And on it goes, to this day. Maybe the biggest loss is that we didn't bottom the issues with the Sulzer 12VPA, a top engine with massive potential. SNCF sorted them. Well you could write a book about it. Ah maybe I should. !

 

[Heritage-DMU]

Traction Magazine (I think) years ago had a list of locos and their miles per casualty, it would take me a long time to dig it out but as I recall of all the classes that lasted more than a few years the class 50s were pretty bad, even after being refurbed. The top class was the 20s.

 

[Cowley]

Traction Magazine (I think) years ago had a list of locos and their miles per casualty, it would take me a long time to dig it out but as I recall of all the classes that lasted more than a few years the class 50s were pretty bad, even after being refurbed. The top class was the 20s.

That doesn’t surprise me at all. After refurbishment if the 50s had been doing the work that they were originally designed for on the WCML, especially after they’d been somewhat simplified by it, then they’d have probably been quite at home on those duties. But the West of England route was really hard on them (and any locomotive actually), plus the fact that if they failed in one of the single line sections it caused a very public nightmare...
I have a feeling that the Old Oak allocated ones on the Thames Valley services fared a little better?

 

[Richard Scott]

Traction Magazine (I think) years ago had a list of locos and their miles per casualty, it would take me a long time to dig it out but as I recall of all the classes that lasted more than a few years the class 50s were pretty bad, even after being refurbed. The top class was the 20s.

The 50s in reality were no worse than any other type 4 but when they failed it was usually expensive. Remember seeing miles per casualty figures and some 50s were managing in excess of 20,000 miles per casualty (admittedly this was rare most doing around half that) taking into account use on punishing routes such as Waterloo Exeter they did quite well. 47s fared no better on this route. Used to ride behind 50s a lot on this route in early 90s and had three failures - 50036/37 wouldn't multiple and same fault with 50030+50050 (believe that was the pair) and 50046 needed a drink at Salisbury. Nothing disastrous and all locos got train to destination. Never had one totally sit down.

 

[Tynwald]

Traction Magazine (I think) years ago had a list of locos and their miles per casualty, it would take me a long time to dig it out but as I recall of all the classes that lasted more than a few years the class 50s were pretty bad, even after being refurbed. The top class was the 20s.

Class 20 were pretty good. But there were a lot of changes made, during the long build run. The early locos had KV5 load reg, and carbon pile AVR. Late locos had KV10 load reg (same as class 50), and HSD electronic AVR. These were much more troublesome. The 8SVT engine also suffered balancer shaft failures.

 

[Cowley]

The 50s in reality were no worse than any other type 4 but when they failed it was usually expensive. Remember seeing miles per casualty figures and some 50s were managing in excess of 20,000 miles per casualty (admittedly this was rare most doing around half that) taking into account use on punishing routes such as Waterloo Exeter they did quite well. 47s fared no better on this route. Used to ride behind 50s a lot on this route in early 90s and had three failures - 50036/37 wouldn't multiple and same fault with 50030+50050 (believe that was the pair) and 50046 needed a drink at Salisbury. Nothing disastrous and all locos got train to destination. Never had one totally sit down.

I think the only time I had a loco give up entirely on the route was 47804 at Pinhoe from memory.
I do remember plenty of dashes up to Honiton or Axminster to pick up late running stuff featuring NB 47s or 33s though where the original train loco had already been replaced at Salisbury or Yeovil and been left behind in disgrace.

 

[Richard Scott]

I think the only time I had a loco give up entirely on the route was 47804 at Pinhoe from memory.
I do remember plenty of dashes up to Honiton or Axminster to pick up late running stuff featuring NB 47s or 33s though where the original train loco had already been replaced at Salisbury or Yeovil and been left behind in disgrace.

Do remember 60033 dropping as far as Salisbury when 50033 had failed to start at Waterloo, station announcement at Basingstoke went something like "this train will be hauled by premier Brush class 60 no. 60033 instead of the knackered old English Electric class 50", the 50 fans were not amused. 60 was replaced by pair of 33s at Salisbury. 47322 also out that day, haunts me now as 57002 as seems to be a pet railtour loco!!!

 

[Cowley]

Do remember 60033 dropping as far as Salisbury when 50033 had failed to start at Waterloo, station announcement at Basingstoke went something like "this train will be hauled by premier Brush class 60 no. 60033 instead of the knackered old English Electric class 50", the 50 fans were not amused. 60 was replaced by pair of 33s at Salisbury. 47322 also out that day, haunts me now as 57002 as seems to be a pet railtour loco!!!

Brilliant.

 

[Journeyman]

Nothing was perfect, and most classes had there achillies heel. NBL stuff was very bad post steam. The MAN engines and Voith transmissions they made under license were dreadful.

I think this was down to two things, one I've seen documented and another which is a bit more hearsay. Apparently poorer quality materials were used in the licence built engines, which is widely known about, but I've also heard it suggested that all the original drawings were in metric units. NBL converted everything to Imperial, but the calculations weren't accurate enough, so components didn't fit together properly.

 

[D6130]

I think the class 29 would be in with a shout. They ran in pairs, so that the back up loco could take over if the prime mover failed.

It was the original NBL/MAN-engined locos (TOPS class 21) that had to run in pairs on passenger workings and they would be my choice for the most unreliable diesel locos. In fairness, the Paxman re-engined examples (class 29) were a lot more reliable, although not entirely failure-proof, and were usually rostered singly on the West Highland and Glasgow-Dundee services during the 1966-71 period. The problem that put paid to their career was the fact that they had a non-standard electro-magnetic control system (orange circle coupling code) and therefore could not run in multiple with any other class plus, as a non-standard class of only twenty locos, obtaining spares became a major issue. On the credit side, they were popular with crews as, having Commonwealth bogies, they rode extremely well - unlike the 26s and 27s, which would rock, sway and bounce around all over the place at speed.

 

[Tynwald]

I think this was down to two things, one I've seen documented and another which is a bit more hearsay. Apparently poorer quality materials were used in the licence built engines, which is widely known about, but I've also heard it suggested that all the original drawings were in metric units. NBL converted everything to Imperial, but the calculations weren't accurate enough, so components didn't fit together properly.

That sounds very likely. Heard about the poor quality materials, but I am sure the latter will be correct also.

 

[Heritage-DMU]

The 50s in reality were no worse than any other type 4 but when they failed it was usually expensive. Remember seeing miles per casualty figures and some 50s were managing in excess of 20,000 miles per casualty (admittedly this was rare most doing around half that) taking into account use on punishing routes such as Waterloo Exeter they did quite well. 47s fared no better on this route. Used to ride behind 50s a lot on this route in early 90s and had three failures - 50036/37 wouldn't multiple and same fault with 50030+50050 (believe that was the pair) and 50046 needed a drink at Salisbury. Nothing disastrous and all locos got train to destination. Never had one totally sit down.

I read another article some time ago about the 50s the author saying that they had suffered from Derby 'Toytown' mentality - that is instead of them being similar to DP2 they put lots of extra gizmos in them which affected reliability. I'm not out to bash 50s I was just struck by the miles per casualty figure despite them being rebuilt.

 

[gimmea50anyday]

If you compare the English 50s with the Portuguese variant, the Portuguese models were far simpler and didn't feature the electronic "brains" the British ones had, also the generator was always ropey mainly down to dirt ingress as it was supposed to be in the clean air compartment but the air cleaners didn't work particularly well. Had 50s received alternators their history may have turned out very different as their use by Intercity for crosscountry duties was in the pipeline, but eventually the long range 47/8 program was introduced instead due to crew and depot familiarity and 50s being predominantly Western region familiar locos were taken on by NSE - even tho the variety of 47s in both build and modification made them far from standard.
The Waterloo Exeter "Mule" was particular taxing for 50s due to the combination of high speed running on lines hammered by heavy motorised bogies of EMUs on the SWML combined with the high demand of the start stop nature of the hilly route West of Salisbury. It has actually been proven that this route is far more suited to hydraulic traction over DC electrical traction power as hydraulic transmission can shock absorb with better tolerances. When the King's Lynn 47/4s were drafted in they also suffered from the demands of the route and control found themselves pinching anything they could get their hands on. In contrast the high speed semi fast workings of 50s on Thames valley duties and GWML duties to Plymouth suited the class far better so yes Old Oak 50s were more reliable, but laira had a harder job of maintaining them under more challenging workloads, and to be fair both did a sterling job. There was also some deliberate fiddling of diagramming which saw the 47s allocated to old oak duties while the 50s eked out their days on the mule in order to justify the financial outlay of the 159s by demonstrating the failure rate of the existing traction on paper compared to other routes. The reality is both 47s and 50s were just as knackered and needed overhauls and reliability mods.

 

[Master Cutler]

The list of locomotive components causing down time must include the train heating boilers fitted to the new diesel stock prior electric heating of rolling stock.
The Spanner boilers on the 55s were particularly troublesome.

 

[Cowley]

If you compare the English 50s with the Portuguese variant, the Portuguese models were far simpler and didn't feature the electronic "brains" the British ones had, also the generator was always ropey mainly down to dirt ingress as it was supposed to be in the clean air compartment but the air cleaners didn't work particularly well. Had 50s received alternators their history may have turned out very different as their use by Intercity for crosscountry duties was in the pipeline, but eventually the long range 47/8 program was introduced instead due to crew and depot familiarity and 50s being predominantly Western region familiar locos were taken on by NSE - even tho the variety of 47s in both build and modification made them far from standard.
The Waterloo Exeter "Mule" was particular taxing for 50s due to the combination of high speed running on lines hammered by heavy motorised bogies of EMUs on the SWML combined with the high demand of the start stop nature of the hilly route West of Salisbury. It has actually been proven that this route is far more suited to hydraulic traction over DC electrical traction power as hydraulic transmission can shock absorb with better tolerances. When the King's Lynn 47/4s were drafted in they also suffered from the demands of the route and control found themselves pinching anything they could get their hands on. In contrast the high speed semi fast workings of 50s on Thames valley duties and GWML duties to Plymouth suited the class far better so yes Old Oak 50s were more reliable, but laira had a harder job of maintaining them under more challenging workloads, and to be fair both did a sterling job. There was also some deliberate fiddling of diagramming which saw the 47s allocated to old oak duties while the 50s eked out their days on the mule in order to justify the financial outlay of the 159s by demonstrating the failure rate of the existing traction on paper compared to other routes. The reality is both 47s and 50s were just as knackered and needed overhauls and reliability mods.

Very interesting. Thanks for that.

 

[47444]

Bulleid's Leader has to be a top contender. 5 authorised for construction, work started on 3, only 1 completed - never entered service after many trial runs

 

[Journeyman]

Bulleid's Leader has to be a top contender. 5 authorised for construction, work started on 3, only 1 completed - never entered service after many trial runs

To be fair, that was a prototype, and there's been plenty of those that haven't necessarily worked. It's kind of the point, really - new ideas have to be tried. Admittedly the design was asking for trouble because it was so radical, but it's not like 50 were ordered straight off the drawing board.

 

[Master Cutler]

Wasn't the Dukedog a product of two problematic locomotives which never met performance expectations.
The Dukedogs gave good reliable service on the Cambrian routes.

 

[d9009alycidon]

I think this was down to two things, one I've seen documented and another which is a bit more hearsay. Apparently poorer quality materials were used in the licence built engines, which is widely known about, but I've also heard it suggested that all the original drawings were in metric units. NBL converted everything to Imperial, but the calculations weren't accurate enough, so components didn't fit together properly.

Story I heard was that the drawings supplied to NBL were in German and instead of hiring a proper technical translator they asked if anyone was proficient in German and one of the girls from the office who could speak German offered to translate, however she was not familiar with technical terms and made quite a few mistakes, resulting in early production difficulties. I was told by a BR fitter however that what they lacked in technical brilliance they made up for it in sturdiness, and were less prone to damage in small collisions.
I think a lot of problems stemmed from using naval diesel technology on the railways, on board a ship the engine runs at a fairly constant load and there is none of the vibration that a locomotive generates at speed, and when you thrash a loco its reliability will inevitably suffer, for example the poor 27s that went on the Glasgow Edinburgh Push Pulls were put through a duty cycle that was probably never considered at the design stage, the 47/7s even suffered and I remember bunking Eastfield near the end of their spell in charge and the availability on the big whiteboard in the depot was sometimes down around 70%

 

[D6130]

Story I heard was that the drawings supplied to NBL were in German and instead of hiring a proper technical translator they asked if anyone was proficient in German and one of the girls from the office who could speak German offered to translate, however she was not familiar with technical terms and made quite a few mistakes, resulting in early production difficulties. I was told by a BR fitter however that what they lacked in technical brilliance they made up for it in sturdiness, and were less prone to damage in small collisions.
I think a lot of problems stemmed from using naval diesel technology on the railways, on board a ship the engine runs at a fairly constant load and there is none of the vibration that a locomotive generates at speed, and when you thrash a loco its reliability will inevitably suffer, for example the poor 27s that went on the Glasgow Edinburgh Push Pulls were put through a duty cycle that was probably never considered at the design stage, the 47/7s even suffered and I remember bunking Eastfield near the end of their spell in charge and the availability on the big whiteboard in the depot was sometimes down around 70%

I'm surprised to hear that a fitter thought that "what they lacked in technical brilliance they made up for in sturdiness, and were less prone to damage in small collisions". According to Anthony P. Sayer's highly-recommended seminal work "The North British Type 2 Bo-Bo Diesel-Electric Classes 21 & 29", the cabs were one-piece aluminium castings and the book is littered with photos of locomotives with collision damage at one or both ends, which in most cases brought about the loco's premature withdrawal. I can't imagine that this method of construction did a lot to enhance crew safety either!

 

[DJH1971]

On the electric front, Class 84.

You beat me to it there.

I believe they were the first of the 1st generation AC electrics to be withdrawn.

Class 82's & Class 83's barely fared much better either.

 

[Irascible]

The class 74 electro-diesels didn't work very well either - they were rebuilt from the class 71 straight electrics. Both the 17s and 74s had Paxman engines, and it seems most early attempts to use Paxman products ended in failure.

The 17s used engines meant for railcars - I suspect the packaging was not all it could have been ( possibly the same in the 74s ). The 29s seemed to work more or less ( I suspect the packaging in those wasn't great either ). The 74s got the same engine as the 14s, it seems to work in the latter.

 

[matacaster]

Yes, inevitably there were unreliable steam locos. In the early years, there was poor understanding of materials technology. In later years, there was misguided belief that technology applicable to small, low-powered locos could be used on higher-powered locos. There are far too many examples to list here, but notable issues were the Midland's failure to appreciate that bearings suitable for Class 2F & 3F 0-6-0s would work on the Fowler LMSR 7F 0-8-0s and Beyer Garratts. And Robinson, who built some fine 4-4-0s for the GCR, failed to appreciate that radical changes were needed to produce successful 4-6-0s.

Another common problem of older designs of steam locos was leakage of steam, particularly from poorly designed valve gear

Not forgetting Mr bullied peat burning loco. Seems the fireman had a really hot time when it occasionally did work.

Apologies, I missed the mention of Mr bullied above.

 

[Journeyman]

Not forgetting Mr bullied peat burning loco. Seems the fireman had a really hot time when it occasionally did work.

I think you're getting Leader and the peat burner mixed up. The latter was actually modestly successful, it was doomed by CIE's decision to dieselise more than anything else.

 

[randyrippley]

I think this was down to two things, one I've seen documented and another which is a bit more hearsay. Apparently poorer quality materials were used in the licence built engines, which is widely known about, but I've also heard it suggested that all the original drawings were in metric units. NBL converted everything to Imperial, but the calculations weren't accurate enough, so components didn't fit together properly.

You can't machine metric parts on 30/40 year old worn out imperial tooling
Even if the drawings were correct, the machining couldn't be

The 17s used engines meant for railcars - I suspect the packaging was not all it could have been ( possibly the same in the 74s ). The 29s seemed to work more or less ( I suspect the packaging in those wasn't great either ). The 74s got the same engine as the 14s, it seems to work in the latter.

BR insisted the 17s using alloy crankcases despite Paxman objecting and preferring steel. Despite that Paxman still had to pay for the repairs

 

[GRALISTAIR]

The Baby Deltics weren’t exactly reliable

 

[randyrippley]

If anyone wants an idea of what was wrong with NBL's products, read this page

Engines used in BR Western Region diesel-hydraulic locomotives

Western Region diesel-hydraulic locomotive engines.

www.greatwestern.org.uk

especially take note of this list of engine faults on the 22

A report of the principal problems with NBL built locomotives had been prepared by Swindon in September 1962 and read as follows:

(1) In early NBL built MAN engines, great difficulty is experienced in fitting replacement parts, due to non-standard building. Also many failures have been due to poor workmanship e.g. badly fitted taper seats for gears and flanges, additional drilled holes in castings causing oil leaks, balance weights slack on the crankshaft, split pins and locking devices missing, piston rings butting together, and general pipework of poor quality.

(2) Cracked or porous cylinder heads and/or cores plugs leaking.

(3) Exhaust manifold system complicated and unsatisfactory, expansion joints seized, stud threads stripped on cylinder head and manifold joint. Pieces of baffle plate become detached damaging turbo-blower blades. Experiment being introduced with stainless steel bellows to take up expansion and vibration.

(4) Cam followers wear, seize, and cause damage to the camshaft. Occasionally worn followers free themselves, and rotate, and if the tappet clearance has been taken up by adjustment, the push rods are bent by the action of the cams.

(5) Broken top chrome piston rings, thought to be caused either by lack of lubrication due to the severity of the new ring pack introduced to reduce oil consumption, or by ring butting due to build-up of carbon in the ring gap and behind the ring. The ring gap has been increased, but no evidence is yet available of any improvements noticed.

(6) Faulty CAV injectors, with a fractured collar on the spindle, lead to overheating of the burner insert which melts into the cylinder causing damage to pistons, liners and valves.

(7) Big-end bolt breakages mostly attributed to fatigue failures caused by inadequate tightening of the bolts when assembled.

(8) Big-end bearings damaged by the copper blanking plugs working loose in the crankshaft journal oil-ways; modification introduced with thicker collar and hole to facilitate riveting.

(9) Heavy oil leakage from white-metal oil seal at front of crankcase; repair entails re-metalling and reboring.

(10) Failure of ball races on fuel pump drive shaft and cradle.

(11) Insufficient drainage on the combustion air delivery box in the vee of the engine, combined with poor welding causing fuel leaks, leads to accumulation of fuel oil in the air box.

(12) End cover tapered locating dowels work out of the cylinder block causing oil leaks. A dowel retaining clip is now fitted to overcome this defect.

(13) Pistons suffer from thermal cracking of the crown and have to be scrapped .

(14) Excessive wear of piston top ring groove is thought to be caused by hard carbon building up in the wear-groove in the liner, and plain liners are now used whenever possible.

(15) Overspeed device is unreliable due to design weaknesses which are being discussed with the supplier.

(16) Scoring of the lower liner register during assembly has led to water leaks.

(17) Premature flaking of the lead flashing on the 'Glacier' big-end bearing is at present being investigated.

These same remarks also applied to the 58 engines in the Scottish Region in the Class 21 diesel-electrics as they were also fitted with the MAN L12V 18/21 engine, but in addition, they suffered from unnecessary delays in service due to the overheating trip shutting down the engine, which could not then be restarted until the whole system cooled sufficiently. This was altered to allow the engine to idle so that the fan could still operate. They also found that fractures in the connecting rods originated from the serrations on the mating faces due to insufficient radius at the base of the serrations. New rods were fitted, with serrations having a fuller radius, and proved satisfactory.

One root cause of a lot of the troubles with all of the MAN engines was the coupling in the drive to the fuel pumps. Due to the hardening of the rubber inserts, misalignment altered the pump timing which in turn caused overheating in the cylinder heads leading to piston seizures.

Many big-end bearing failures occurred due to the bearing turning in the housing. It was found that it was possible to have as little as one thousandth of an inch nip between bearing and journal. Larger shells with a higher tightening torque were introduced, but there was really insufficient depth of thread in the caps to take this increased torque.

The piston problems were never properly solved and attempts to get UK piston suppliers to supply pistons with Alfin bonded ring inserts did not materialise. They probably felt that it was a thankless task to undertake for such a small market, so the problem was left to Mahle, who were the original supplier. A suggestion was made in 1967, to test pistons made from silicone-aluminium, but this was never started as these engines were soon to be phased out.

Exhaust manifolds were a constant source of trouble having a partition designed to provide a two-part entry into the turbo-charger. This partition fractured, as did the entry pipe itself, but Glasgow works eventually made their own manifolds in mild steel, which were an improvement on the original and a lot cheaper.

In March 1963, the engine in D6123 in the Scottish Region was replaced by a Paxman 'Ventura' engine rated at 1350 hp. This 'Ventura' was similar to the two fitted in D830 (produced at Swindon in 1961) but at the higher rating, which the electrical equipment on the D6100 Class could accommodate. This was followed by nineteen more 'Ventura' replacements in 1965 but the remaining thirty-eight in that Region were allowed to run on until withdrawal in 1968/9. Those in the Scottish Region had suffered more from crankcase cavitation erosion due to water problems. In this Region the water treatment had at first been sodium dichromate, then sodium benzoate nitrate and finally borax/sodium metasilicate, whereas the Western had used the German recommended soluble oil treatment. Reclamation schemes were tried out using shot blasting and spraying with molybdenum and ceramic, but these were not in action long enough to be conclusive.

Some mention should also be made of the similar engines used in the 'Blue Pullman' railcars although these were German built and only rated at 1000 hp. Their performance was generally admitted to have been superior to the NBL built engines, though railcar duties are reckoned to be easier than those on a locomotive installed engine. These ten engines went into service in July 1960 on the LMR transferring to the Western Region in September of that year. They remained in service until 1973 when all the 'Blue Pullman' trains were withdrawn.

During the last few years of their reduced operation these engines had settled to an acceptable life cycle of 4000 hours between overhauls in the 'Warship' locomotives (D833-865). Problems were still occurring in the high-pressure fuel pipes due to cavitation erosion and fracturing of end nipples. Fuel injectors were changed every 3000 hours and all flexible hoses at 4500-6000 hours, according to overhaul procedures. The one feature of these engines that performed very satisfactory was the Napier turbo-charger, which had not previously been tried on MAN engines, and which amazingly worked better on these engines than on many of their own English Electric engines.

I'm surprised to hear that a fitter thought that "what they lacked in technical brilliance they made up for in sturdiness, and were less prone to damage in small collisions". According to Anthony P. Sayer's highly-recommended seminal work "The North British Type 2 Bo-Bo Diesel-Electric Classes 21 & 29", the cabs were one-piece aluminium castings and the book is littered with photos of locomotives with collision damage at one or both ends, which in most cases brought about the loco's premature withdrawal. I can't imagine that this method of construction did a lot to enhance crew safety either!

from http://www.greatwestern.org.uk/d6300m_in.htm

The underframe of the D6300s was built like a tank. Using ' I ' section beams and cross - members which were riveted and welded together and topped by a thick sheet steel floor with aluminium bodywork, bringing the total weight of each locomotive to 68 tons.

 

[O L Leigh]

I think that it's important to draw a few distinctions, as I fear that there's been a fair bit of mud thrown around in this thread so far. For example, there is a difference between something being expensive to run or an idea being tried and rejected and it being unreliable. Plus, as has already been said up-thread, prototypes are always likely to prone to lower availability and longer repair times following failures due to their unique nature.

To pick up on a few specific examples:

It's hardly surprising that the Fell loco was expensive to run given the level of complexity that it used, but that doesn't mean that it was highly unreliable. Six diesel engines (four 500hp Paxman V12s for propulsion and two AEC 150hp inline sixes for the auxilliaries) together with the mechanical transmission is going to add up to a big running bill. It was sidelined only once as far as I am aware after a sheared bolt fell through the transmission, and the fire that finished it off was in the train heating boiler which could have been repaired if British Railways had been sufficiently interested in continuing with the experiment. I'm not sure in quite what context that makes the design "a disaster". What really did for the Fell was that the designers and engineers behind it forgot that "can" does not necessarily mean "should".

Bulleid's various 0-6-6-0Ts were a bit of a mixed bag. Granted, his fetish for chains meant that they leaked oil, but then so did many of his other designs. The Leader was perhaps needlessly over-complicated and suffered for being a prototype, but the slightly simpler "Turf Burner" actually looked like a promising design. The issue with these were that they were being proposed at the wrong time in the history of the railways when diesel traction was starting to look like the way forward, and proved unpopular with the crews who had to work them. As a consequence they were quietly dropped.

NBL do, however, perhaps deserve the kicking that their reputation got. 10800 became known as the "Wonder Engine" during it's time on Brighton shed because of the loco department's daily musing "I wonder if it will work today". Quite how they dropped the ball so comprehensively during the changeover from steam to diesel and electric is a matter of some fact and some fokelore, but it does appear that almost everything they had a hand in fared quite badly and almost certainly hastened the demise of the firm.

I suppose it's also worth bearing in mind that we have the luxury of hindsight. Those heady days in the 1950s especially meant that no-one really knew for sure what would work and what wouldn't, and so quite a few things were tried that didn't work out as well as were hoped. But that's how progress was made. At the start of the modernisation era no-one could say for sure whether mechanical, hydraulic or electric transmissions, and high or low speed diesel engines were the way to go forward. Most things were tried and the failures of the past helped to improve the breed for the future.

 

[birchesgreen]

What didn't help also was BR switching from prototype pilot scheme classes to mass production of diesels because they had to replace steam by a certain date, hence building 117 Claytons whereas it would have been prudent to build a smaller batch first for test. If BR had phased steam out over a longer period as on the continent there would have been a lot less waste and fewer bad locos. But I guess that is a whole other topic.

 

[DustyBin]

I think that it's important to draw a few distinctions, as I fear that there's been a fair bit of mud thrown around in this thread so far. For example, there is a difference between something being expensive to run or an idea being tried and rejected and it being unreliable. Plus, as has already been said up-thread, prototypes are always likely to prone to lower availability and longer repair times following failures due to their unique nature.

To pick up on a few specific examples:

It's hardly surprising that the Fell loco was expensive to run given the level of complexity that it used, but that doesn't mean that it was highly unreliable. Six diesel engines (four 500hp Paxman V12s for propulsion and two AEC 150hp inline sixes for the auxilliaries) together with the mechanical transmission is going to add up to a big running bill. It was sidelined only once as far as I am aware after a sheared bolt fell through the transmission, and the fire that finished it off was in the train heating boiler which could have been repaired if British Railways had been sufficiently interested in continuing with the experiment. I'm not sure in quite what context that makes the design "a disaster". What really did for the Fell was that the designers and engineers behind it forgot that "can" does not necessarily mean "should".

Bulleid's various 0-6-6-0Ts were a bit of a mixed bag. Granted, his fetish for chains meant that they leaked oil, but then so did many of his other designs. The Leader was perhaps needlessly over-complicated and suffered for being a prototype, but the slightly simpler "Turf Burner" actually looked like a promising design. The issue with these were that they were being proposed at the wrong time in the history of the railways when diesel traction was starting to look like the way forward, and proved unpopular with the crews who had to work them. As a consequence they were quietly dropped.

NBL do, however, perhaps deserve the kicking that their reputation got. 10800 became known as the "Wonder Engine" during it's time on Brighton shed because of the loco department's daily musing "I wonder if it will work today". Quite how they dropped the ball so comprehensively during the changeover from steam to diesel and electric is a matter of some fact and some fokelore, but it does appear that almost everything they had a hand in fared quite badly and almost certainly hastened the demise of the firm.

I suppose it's also worth bearing in mind that we have the luxury of hindsight. Those heady days in the 1950s especially meant that no-one really knew for sure what would work and what wouldn't, and so quite a few things were tried that didn't work out as well as were hoped. But that's how progress was made. At the start of the modernisation era no-one could say for sure whether mechanical, hydraulic or electric transmissions, and high or low speed diesel engines were the way to go forward. Most things were tried and the failures of the past helped to improve the breed for the future.

You make some very good points there, it’s easy to be critical with the benefit of hindsight. As somebody mentioned upthread, in the case of early diesels in particular there was an element of ‘operator error’ as BR got to grips with the new technology. Your quite correct as well in saying there is a difference between something being expensive to run or an idea being tried and rejected and it being inherently bad - see 18000, 18100 and GT3 for example(s).