Inter City 125 / HST
Discussion
Flying Phil said:
Yertis said:
Sounds like the Triumph Stag of locomotives - sounds great, wonderful when it works, but underdeveloped and tricky to maintain.
....Yet still in frontline service after 40+ years......not too underdeveloped and tricky to maintain I would have thought!If you want flakey, then NM 55B & 59K deltics would be your weapon of choice.
C2Red said:
It wasn’t really the engine design that was the problem; but the application as you also suggested.
I’ve built, tested and rebuilt a few , quite a few returns from BR.
From memory the trains cooling systems weren’t up to the task.
We had some rebuilt and running on the testbeds at over 110 degrees on the water jackets, just to try and replicate the BR issues.
It’s true, we had a few unexpected crankcase ventilation mods.... but not that many.
Treated properly, and not left idling for hours on end in the sheds would also have helped, having witnessed the BR sheds and operations, I’m confident they as in BR simply didn’t know what they were expected to do with them.
If I remember correctly, the problems with the Valenta in the early days of the HST were a combination of an under-specced cooler group (which had been specced by BR and designed and built by a different contractor - not Paxman), a run of particularly hot summers and various issues with BR maintenance - oil leaks from ancillary components (especially the cooling fan motors) were not attended to which attracted dust and dirt and built up in the radiator cores. The radiator cores were 'cleaned' by water lances, which only drove the gunk further into the radiators and also damaged the finning. I think there were some Paxman-related issues to do with an excess of gasket compound used somewhere in the engine which extruded into the cooling passages, cooked hard and then broke off and ended up lodged somewhere else in the cooling system (whoever mentioned the Triumph Stag was very on the money, it seems!)I’ve built, tested and rebuilt a few , quite a few returns from BR.
From memory the trains cooling systems weren’t up to the task.
We had some rebuilt and running on the testbeds at over 110 degrees on the water jackets, just to try and replicate the BR issues.
It’s true, we had a few unexpected crankcase ventilation mods.... but not that many.
Treated properly, and not left idling for hours on end in the sheds would also have helped, having witnessed the BR sheds and operations, I’m confident they as in BR simply didn’t know what they were expected to do with them.
The biggest issue was the old rail traction bugbear of thermal cycling - the HSTs were run either flat out or at idle and did that idle/full power cycle some ridiculous number of times per hour during an ordinary working day, interspersed with long periods of idling between duties. All of which is killer stuff for diesel engines, and especially relatively highly-strung ones like the Valenta. I believe it's going quickly from full power to idle (as when checked by signals or slowing for stations) which does the damage rather than the other way round.
Rail traction is generally regarded as the toughest operating environment for engines, and plenty of engines which were perfectly reliable in stationary, industrial, road and marine applications prove not to be up to the test. As well as the on/off cycling and the frequent changes in load and speed, there's the relatively dirty conditions and the fact that the engine has to work very hard while largely unattended (in contrast to, say, a marine application, where engines are monitored and tended by specialist engineering crew), all while in a small enclosed space shared with a lot of other equipment. Then there are the constant vibrations and shocks of railway work and the fact that a locomotive, for all its heft, is not the sturdiest base for a heavy-duty diesel engine. I'm sure I read somewhere that there were a few Class 47s (or 50s - maybe both) which the stats showed got through engines much more quickly than their classmates, and it turned out to be due to badly-aligned frames at the works which were putting undue stresses on the crankcase and bearings.
miniman said:
Southerner said:
Flying Phil said:
I did some short HST rides in the last couple of weeks - and the seats are still much more comfortable than in the 222 units!
And the seats on the 222s are uber-luxury compared to the Hitachi 800 stuff that's swiftly replacing everything else! 
Where I did my apprenticeship, the Paxman Valentas were being evaluated for use on submarine generating sets. This involved running for hours at various power settings against a dynamometer (water brake), then stripping the engine down to assess wear and carbon build up.
The bit I particularly remember is pushing the piston and conrod out the top of the cylinder with a cranked lever, through a door in the side of the crankcase. Having two pivots, (one in the lever plus the gudgeon pin) meant the thing did not want to stay in line, and it wouldn't come out if it wasn't in line. The other hinderance was the ridge of carbon that built up above the top ring. Anyway, I remember it being a real pig of a job.
As I recall, fuel consumption at full power was 125 gallons per hour, so in the train, it would have been 1mpg per engine.
The comment about sewage being discharged straight from the toilets, reminded me of a more recent place that I worked, just to the East of Reading. Our car park was adjacent to the South facing railway embankment, and there were bountiful apple trees growing on the embankment side of the fence. I always wondered what was the most exotic fruit or vegetable found growing beside well fertilized tracks.
The bit I particularly remember is pushing the piston and conrod out the top of the cylinder with a cranked lever, through a door in the side of the crankcase. Having two pivots, (one in the lever plus the gudgeon pin) meant the thing did not want to stay in line, and it wouldn't come out if it wasn't in line. The other hinderance was the ridge of carbon that built up above the top ring. Anyway, I remember it being a real pig of a job.
As I recall, fuel consumption at full power was 125 gallons per hour, so in the train, it would have been 1mpg per engine.
The comment about sewage being discharged straight from the toilets, reminded me of a more recent place that I worked, just to the East of Reading. Our car park was adjacent to the South facing railway embankment, and there were bountiful apple trees growing on the embankment side of the fence. I always wondered what was the most exotic fruit or vegetable found growing beside well fertilized tracks.
GliderRider said:
Where I did my apprenticeship, the Paxman Valentas were being evaluated for use on submarine generating sets. This involved running for hours at various power settings against a dynamometer (water brake), then stripping the engine down to assess wear and carbon build up.
The bit I particularly remember is pushing the piston and conrod out the top of the cylinder with a cranked lever, through a door in the side of the crankcase. Having two pivots, (one in the lever plus the gudgeon pin) meant the thing did not want to stay in line, and it wouldn't come out if it wasn't in line. The other hinderance was the ridge of carbon that built up above the top ring. Anyway, I remember it being a real pig of a job.
As I recall, fuel consumption at full power was 125 gallons per hour, so in the train, it would have been 1mpg per engine.
The comment about sewage being discharged straight from the toilets, reminded me of a more recent place that I worked, just to the East of Reading. Our car park was adjacent to the South facing railway embankment, and there were bountiful apple trees growing on the embankment side of the fence. I always wondered what was the most exotic fruit or vegetable found growing beside well fertilized tracks.
Interesting, the submarine engines were a mild variation on a theme from memory; not too dissimilar but different enough; had one from memory at St Botolphs the annexed site of Paxmans on endurance testing for 00’s of hours. Cherry red exhaust systems. The bit I particularly remember is pushing the piston and conrod out the top of the cylinder with a cranked lever, through a door in the side of the crankcase. Having two pivots, (one in the lever plus the gudgeon pin) meant the thing did not want to stay in line, and it wouldn't come out if it wasn't in line. The other hinderance was the ridge of carbon that built up above the top ring. Anyway, I remember it being a real pig of a job.
As I recall, fuel consumption at full power was 125 gallons per hour, so in the train, it would have been 1mpg per engine.
The comment about sewage being discharged straight from the toilets, reminded me of a more recent place that I worked, just to the East of Reading. Our car park was adjacent to the South facing railway embankment, and there were bountiful apple trees growing on the embankment side of the fence. I always wondered what was the most exotic fruit or vegetable found growing beside well fertilized tracks.
All fuel consumption from memory was lb’s/hp/hr as a specific consumption rate. .4 was the number I have in mind, but that detail is now 40 years old in my head..
Never did field work, glad I didn’t, it was bad enough in a test cell with only 2ft or so per side to work in.
Edited by C2Red on Sunday 16th May 16:53
2xChevrons said:
C2Red said:
It wasn’t really the engine design that was the problem; but the application as you also suggested.
I’ve built, tested and rebuilt a few , quite a few returns from BR.
From memory the trains cooling systems weren’t up to the task.
We had some rebuilt and running on the testbeds at over 110 degrees on the water jackets, just to try and replicate the BR issues.
It’s true, we had a few unexpected crankcase ventilation mods.... but not that many.
Treated properly, and not left idling for hours on end in the sheds would also have helped, having witnessed the BR sheds and operations, I’m confident they as in BR simply didn’t know what they were expected to do with them.
If I remember correctly, the problems with the Valenta in the early days of the HST were a combination of an under-specced cooler group (which had been specced by BR and designed and built by a different contractor - not Paxman), a run of particularly hot summers and various issues with BR maintenance - oil leaks from ancillary components (especially the cooling fan motors) were not attended to which attracted dust and dirt and built up in the radiator cores. The radiator cores were 'cleaned' by water lances, which only drove the gunk further into the radiators and also damaged the finning. I think there were some Paxman-related issues to do with an excess of gasket compound used somewhere in the engine which extruded into the cooling passages, cooked hard and then broke off and ended up lodged somewhere else in the cooling system (whoever mentioned the Triumph Stag was very on the money, it seems!)I’ve built, tested and rebuilt a few , quite a few returns from BR.
From memory the trains cooling systems weren’t up to the task.
We had some rebuilt and running on the testbeds at over 110 degrees on the water jackets, just to try and replicate the BR issues.
It’s true, we had a few unexpected crankcase ventilation mods.... but not that many.
Treated properly, and not left idling for hours on end in the sheds would also have helped, having witnessed the BR sheds and operations, I’m confident they as in BR simply didn’t know what they were expected to do with them.
The biggest issue was the old rail traction bugbear of thermal cycling - the HSTs were run either flat out or at idle and did that idle/full power cycle some ridiculous number of times per hour during an ordinary working day, interspersed with long periods of idling between duties. All of which is killer stuff for diesel engines, and especially relatively highly-strung ones like the Valenta. I believe it's going quickly from full power to idle (as when checked by signals or slowing for stations) which does the damage rather than the other way round.
Rail traction is generally regarded as the toughest operating environment for engines, and plenty of engines which were perfectly reliable in stationary, industrial, road and marine applications prove not to be up to the test. As well as the on/off cycling and the frequent changes in load and speed, there's the relatively dirty conditions and the fact that the engine has to work very hard while largely unattended (in contrast to, say, a marine application, where engines are monitored and tended by specialist engineering crew), all while in a small enclosed space shared with a lot of other equipment. Then there are the constant vibrations and shocks of railway work and the fact that a locomotive, for all its heft, is not the sturdiest base for a heavy-duty diesel engine. I'm sure I read somewhere that there were a few Class 47s (or 50s - maybe both) which the stats showed got through engines much more quickly than their classmates, and it turned out to be due to badly-aligned frames at the works which were putting undue stresses on the crankcase and bearings.
Always amazes me how inadequate cooling systems are so often the weak link. Why do the engineering teams seemingly not learn past lessons and build in sufficient headroom to accommodate sustained real world (ie non ideal) operating and maintenance conditions? Yes, they’re fine when they’re new/on the test bed. But out in the field where there’s dust, pollen, leaves, oil mist, whatever, that invariably contaminates the cooling system and degrades its performance, seemingly catching everyone by surprise.
HST had its issues with this, as have the Class 800’s, and various others along the way.
HST had its issues with this, as have the Class 800’s, and various others along the way.
Yertis said:
2xChevrons said:
C2Red said:
It wasn’t really the engine design that was the problem; but the application as you also suggested.
I’ve built, tested and rebuilt a few , quite a few returns from BR.
From memory the trains cooling systems weren’t up to the task.
We had some rebuilt and running on the testbeds at over 110 degrees on the water jackets, just to try and replicate the BR issues.
It’s true, we had a few unexpected crankcase ventilation mods.... but not that many.
Treated properly, and not left idling for hours on end in the sheds would also have helped, having witnessed the BR sheds and operations, I’m confident they as in BR simply didn’t know what they were expected to do with them.
If I remember correctly, the problems with the Valenta in the early days of the HST were a combination of an under-specced cooler group (which had been specced by BR and designed and built by a different contractor - not Paxman), a run of particularly hot summers and various issues with BR maintenance - oil leaks from ancillary components (especially the cooling fan motors) were not attended to which attracted dust and dirt and built up in the radiator cores. The radiator cores were 'cleaned' by water lances, which only drove the gunk further into the radiators and also damaged the finning. I think there were some Paxman-related issues to do with an excess of gasket compound used somewhere in the engine which extruded into the cooling passages, cooked hard and then broke off and ended up lodged somewhere else in the cooling system (whoever mentioned the Triumph Stag was very on the money, it seems!)I’ve built, tested and rebuilt a few , quite a few returns from BR.
From memory the trains cooling systems weren’t up to the task.
We had some rebuilt and running on the testbeds at over 110 degrees on the water jackets, just to try and replicate the BR issues.
It’s true, we had a few unexpected crankcase ventilation mods.... but not that many.
Treated properly, and not left idling for hours on end in the sheds would also have helped, having witnessed the BR sheds and operations, I’m confident they as in BR simply didn’t know what they were expected to do with them.
The biggest issue was the old rail traction bugbear of thermal cycling - the HSTs were run either flat out or at idle and did that idle/full power cycle some ridiculous number of times per hour during an ordinary working day, interspersed with long periods of idling between duties. All of which is killer stuff for diesel engines, and especially relatively highly-strung ones like the Valenta. I believe it's going quickly from full power to idle (as when checked by signals or slowing for stations) which does the damage rather than the other way round.
Rail traction is generally regarded as the toughest operating environment for engines, and plenty of engines which were perfectly reliable in stationary, industrial, road and marine applications prove not to be up to the test. As well as the on/off cycling and the frequent changes in load and speed, there's the relatively dirty conditions and the fact that the engine has to work very hard while largely unattended (in contrast to, say, a marine application, where engines are monitored and tended by specialist engineering crew), all while in a small enclosed space shared with a lot of other equipment. Then there are the constant vibrations and shocks of railway work and the fact that a locomotive, for all its heft, is not the sturdiest base for a heavy-duty diesel engine. I'm sure I read somewhere that there were a few Class 47s (or 50s - maybe both) which the stats showed got through engines much more quickly than their classmates, and it turned out to be due to badly-aligned frames at the works which were putting undue stresses on the crankcase and bearings.
Southerner said:
anonymous said:
[redacted]
What do ya think of it? Controversial eh 
Quite like it myself. For the less bearded among us, it's the first time one has ever operated without yellow fronts, due to them having upgraded the lights to the latest standards, crucially including the high level one above the windscreen. Nice.
DoctorX said:
I love these trains. It’s a shame the headlights were changed from the originals and look like they’ve had a trip to Halfords. I assume this was some regulation or other?
Not so much a change of regs, just better tech. As with car manufacturers, train headlights have changed from candle-watt bulbs to far better stuff over the past 15 years or so, with new light clusters being fitted to a lot of older stuff along the way. The normal set up now is a combined LED marker/tail light on the outside, and the main headlamps on the inside (only one headlight is used at a time, one side for daylight and the other for night).The Blue Pullman effort does conform to newer regs, which dictate that a central high level headlight, and both main headlights lit together, removes the need for a yellow front end.
Edited by Southerner on Monday 17th May 06:39
Edited by Southerner on Monday 17th May 06:40
A great video from the National Railway Museum called "Inside the First InterCity 125 | Curator with a Camera"
https://www.youtube.com/watch?v=KeD_2-PVVKg
There's also an Australian version called XPT which has some changes and less power.
https://en.wikipedia.org/wiki/New_South_Wales_XPT
A pair of Paxman Valenta engines as originally used in the HST were also used to power the Victoria-class submarine, there are still four of the subs still in use by the Canadians.
https://www.youtube.com/watch?v=KeD_2-PVVKg
There's also an Australian version called XPT which has some changes and less power.
https://en.wikipedia.org/wiki/New_South_Wales_XPT
A pair of Paxman Valenta engines as originally used in the HST were also used to power the Victoria-class submarine, there are still four of the subs still in use by the Canadians.
Skyrocket21 said:
A pair of Paxman Valenta engines as originally used in the HST were also used to power the Victoria-class submarine, there are still four of the subs still in use by the Canadians.
That explains why the engines on which I worked were often referred to as Paxman SSKs. I thought they were for back up generators on nuclear subs, whereas they were actually for the diesel electric Upholder/Victoria class. Interesting thread. Never really considered until now how tough the railway environment is on diesel engines.
One things I've always wondered is why the train engines are left idling for such extended periods. Presumably there's a technical reason why the engines are not just shut down if the train is not going to move for again, say within the next 15 minutes? (at major stations or depos, where external power could be connected up to power the coaches)
One things I've always wondered is why the train engines are left idling for such extended periods. Presumably there's a technical reason why the engines are not just shut down if the train is not going to move for again, say within the next 15 minutes? (at major stations or depos, where external power could be connected up to power the coaches)
Agreed, v. interesting thread. I spent a summer taking one to Nottingham and back weekly a few years back (2015)
Got chatting to the driver one day, and 2 things really struck me:
1. He really did care. It wasn't just a job, he liked the engines and enjoyed driving them
2. Didn't appreciate this at the time - but reading this thread, it now does. I remember him remarking that one of the motors was running a bit hot so he was taking it a bit easier on that motor. I guess was wishing to avoid a piston being used as the mixing stick between the oil and coolant.
Got chatting to the driver one day, and 2 things really struck me:
1. He really did care. It wasn't just a job, he liked the engines and enjoyed driving them
2. Didn't appreciate this at the time - but reading this thread, it now does. I remember him remarking that one of the motors was running a bit hot so he was taking it a bit easier on that motor. I guess was wishing to avoid a piston being used as the mixing stick between the oil and coolant.
Edited by Arnie Cunningham on Tuesday 18th May 11:31
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