Most Unreliable Locomotive

[Inversnecky]

Which was the most unreliable locomotive, then or now?

I was surprised to read recently that the Class 47, the one loco I saw more than any other as a youth, on average lasted 16 days before developing a fault and needing servicing.

 

[CW2]

In their later years the class 27s went through an awful patch of non-reliability. Worst of them all was 27014. I recall Control log entries starting "Today's failure of 27014 took place at ...". I think in the end it was diagnosed as some form of fungus growing in the diesel fuel system, and periodically blocking the fuel lines. I had it re-engine a Scarborough - Queen Street at Edinburgh. The engine actually shut down coming down from Cowlairs, but we were able to coast safely to a (silent) halt at Queen Street with nobody the wiser!

Although I loved them dearly, class 40s were prone to boiling themselves dry and then shutting down when worked hard in hot weather. You could often get them going again by giving them some water - whereas if a 47 failed on you it was usually something serious and electrical, often accompanied by a warm burning insulation smell.

 

[36270k]

Which was the most unreliable locomotive, then or now?

I was surprised to read recently that the Class 47, the one loco I saw more than any other as a youth, on average lasted 16 days before developing a fault and needing servicing.

When Class 47's were new, they had a lot of main generator problems as well as engine defects.
Generator failures were reduced when the engines were derated from 2750 to 2580hp

A DC generator has a limit of about 2500hp for reliability. The main weakness being the commutator and brushgear.

In the BR 1970's era, maintenance quality was very poor. WR Class 47 's in particular suffered from severe oil leaks.
When a 47 overheated, it was often caused by loss of hydraulic oil in the cooling fan drive.

 

[Irascible]

Diesel wise, probably something built by NBL, or the baby Deltics, or the 30s. There were some apparently horrendously unreliable engines in the early days of steam, as you might imagine...

Some diesel classes have had patches of unreliability, like the 50s which turned quite a few journeys into an adventure when I was a young lad.

 

[DustyBin]

Diesel wise, probably something built by NBL, or the baby Deltics, or the 30s. There were some apparently horrendously unreliable engines in the early days of steam, as you might imagine...

Some diesel classes have had patches of unreliability, like the 50s which turned quite a few journeys into an adventure when I was a young lad.

Yes there were various short lived classes in the early days of diesel, some were frankly disastrous!

The 30s are notable as they would become 31s, a class with which we are all familiar, as we are with the aforementioned 47s which remain in service to this day.

Actually that reminds me, Class 48?

 

[birchesgreen]

The Class 17 was very unreliable, nearly half the fleet was unavailable at times.

 

[Master Cutler]

Weren't the 56s unreliable leading to the 47s being retained for longer?

 

[dk1]

Weren't the 56s unreliable leading to the 47s being retained for longer?

The Romanian examples certainly where. Didn’t they need complete re-wiring or something similar?

 

[xotGD]

On the electric front, Class 84.

 

[fishquinn]

Going for a more recent example, 91112 certainly had a reputation in its later years (lost count of the number of failures in 2018/19)

 

[341o2]

Class 28 Metrovick Co-Bo. They used 2 as opposed to 4 stroke engines which proved unreliable to the extent that the entire class was returned to the manufacturers for remedial work, also to cure the problem of cab windows falling out. The engines continued to be unreliable and the entire class withdrawn 1967/8 after only 11 years of service.

 

[Spartacus]

The Romanian examples certainly where. Didn’t they need complete re-wiring or something similar?

Yeah, and the rest. More a case of terrible build quality, plus when changes were made they kept building them to the same faulty standard they’d first been given!

 

[DustyBin]

Class 28 Metrovick Co-Bo. They used 2 as opposed to 4 stroke engines which proved unreliable to the extent that the entire class was returned to the manufacturers for remedial work, also to cure the problem of cab windows falling out. The engines continued to be unreliable and the entire class withdrawn 1967/8 after only 11 years of service.

Yes they were Crossley engines IIRC. Two strokes aren’t inherently problematic, they can also be found in Class 55s (admittedly not without their own issues!) and the modern Class 68.

 

[Richard Scott]

Yes they were Crossley engines IIRC. Two strokes aren’t inherently problematic, they can also be found in Class 55s (admittedly not without their own issues!) and the modern Class 68.

67s not 68s which are four stroke.

 

[DustyBin]

67s not 68s which are four stroke.

Oops apologies that’s correct!

 

[ac6000cw]

Yes they were Crossley engines IIRC. Two strokes aren’t inherently problematic, they can also be found in Class 55s (admittedly not without their own issues!) and the modern Class 68.

....and the 66's of course.

Actually it's the reliability and lower mechanical complexity of the EMD 645 (as used in our 57's and 59's) and 710 series two-strokes that owners & operators like - it's been a strength of EMD products for many years.

 

[Master Cutler]

I understand the Fell locomotive was about as unreliable as it gets.
There are figures somewhere, perhaps I've seen them at the NRM, that show the high service costs against operating hours which are horrendous.
However, I love the mechanical transmission concept all be it very complicated, and believe if the locomotive had not caught fire in Manchester the design could have been developed and evolved into a good shunter/medium freight locomotive.

 

[Elecman]

I understand the Fell locomotive was about as unreliable as it gets.
There are figures somewhere, perhaps I've seen them at the NRM, that show the high service costs against operating hours which are horrendous.
However, I love the mechanical transmission concept all be it very complicated, and believe if the locomotive had not caught fire in Manchester the design could have been developed and evolved into a good shunter/medium freight locomotive.

Beaten to it the Fell was a total disaster

 

[Richard Scott]

....and the 66's of course.

Actually it's the reliability and lower mechanical complexity of the EMD 645 (as used in our 57's and 59's) and 710 series two-strokes that owners & operators like - it's been a strength of EMD products for many years.

Believe Kolomna tried to emulate the EMD engines when the M62 was designed but weren't too successful, high fuel consumption and emissions were a problem.

 

[XAM2175]

Actually it's the reliability and lower mechanical complexity of the EMD 645 (as used in our 57's and 59's) and 710 series two-strokes that owners & operators like - it's been a strength of EMD products for many years.

Noting of course that it was Foster Yeoman's dismal experience with Class 56 reliability that lead them to invite EMD to tender for what became the Class 59. It's interesting to wonder how things would have developed had EMD not got that break, which as we know lead to the huge success of the Class 66 here and even on the continent too.

 

[Bevan Price]

Diesel wise, probably something built by NBL, or the baby Deltics, or the 30s. There were some apparently horrendously unreliable engines in the early days of steam, as you might imagine...

Some diesel classes have had patches of unreliability, like the 50s which turned quite a few journeys into an adventure when I was a young lad.

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

 

[Cymroglan]

I absolutely love the Class 50s, but in my experience they did fail very often when working the Waterloo - Exeter services back in the 1980s. I know nothing about how locos work, but I think I read somewhere that the original design was unnecessary complicated by BR requirement? I may well have got this wrong, so please don’t shout at me!

 

[Master Cutler]

In terms of improving reliability, the 55s were kept in fairly reliable service by swapping power units between locomotives.

 

[Richard Scott]

I absolutely love the Class 50s, but in my experience they did fail very often when working the Waterloo - Exeter services back in the 1980s. I know nothing about how locos work, but I think I read somewhere that the original design was unnecessary complicated by BR requirement? I may well have got this wrong, so please don’t shout at me!

Generator issues were main problem. Was overstressed, English Electric wanted to use an alternator but BR wanted a generator. Should have been replaced at refurbishment but BR said cost was prohibitive. Also the KV10 electronic load regulator could be a source of issues.

 

[Cowley]

Generator issues were main problem. Was overstressed, English Electric wanted to use an alternator but BR wanted a generator. Should have been replaced at refurbishment but BR said cost was prohibitive. Also the KV10 electronic load regulator could be a source of issues.

I remember one week around 1988 when there were so many 50s laid up at Laira with various faults that there were only two or three out working the Waterloo route. The rest of the services were all powered by a mixed bag of parcels 47/4s and 33s.

 

[Journeyman]

The Class 17 was very unreliable, nearly half the fleet was unavailable at times.

I believe they were considered just about the worst of the lot for early diesels, and certainly had very short lives for that reason - only the class 14s had shorter lives, and that was because work for them disappeared, rather than any problems with the locos. Even the abysmally unreliable class 21/29 NBL locos managed longer lives.

In the end BR gave up and ordered a bunch of extra class 20s to replace them.

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.

 

[Taunton]

It's not necessarily the locomotive itself. For example, the Pressed Steel dmus, stalwarts of Paddington suburban operations for 30 years, had very poor availability figures in their first couple of years because the fitters were not adequately trained/skilled, the consumable spares would not be in stock, or there was only one copy of the manual. Etc. Once cracked, a great improvement. Included in "skills" was finding that for an issue out on the line the fitter could not go out in the van, because they didn't have a driving licence, and when they eventually travelled there by train they could not take the likely heavy tools/parts until they got there and diagnosed it, whereupon someone else would have to come out with these.

BR buying the cheapest bottom-grade diesel fuel and it sludging up the fuel tanks and lines can't really be laid at the locos.

 

[simon7929]

I seem to think 31s were Mirlees powered originally. But reliability was so poor. They replaced the units with EE.

 

[delt1c]

I absolutely love the Class 50s, but in my experience they did fail very often when working the Waterloo - Exeter services back in the 1980s. I know nothing about how locos work, but I think I read somewhere that the original design was unnecessary complicated by BR requirement? I may well have got this wrong, so please don’t shout at me!

When the 50’s were working the WCML they were nicknamed the 50/50’s not because there was 50 of them but because it was a 50/50 chance of failure

 

[raetiamann]

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.