Hitachi trains grounded

[boxbrownie]

18 minutes ago, Bernard Lamb said:

If you started there and fitted in you were there for life.

You were still looked after long after the founder had retired and died.

All now gone in Hemel and the site is the main Royal Mail depot.

Bernard

Upon my Uncles passing the procession passed by the factory and his work mates turned out to pay their respects.....very touching.

[LNER4479]

1 hour ago, boxbrownie said:

It looked to be the part of the box section to which the yaw damper is bolted, not at the lifting pad end.

No - it is the dark coloured casting, like so:

 

The whole thing I've outlined in red is the yaw damper bracket. Its role is to transfer the load from the yaw damper into the body structure, thereby dissipating the load.

 

The load I'm talking about is that which comes about from rapid oscillation of the bogie as it reacts to forces whilst travelling along. It shouldn't happen - but it does. Although it's designed to run in a perfect straight line (using the opposed cones effect of the wheelsets - conicity), it's actually reacting all the time to tiny variations in track geometry and can oscillate rotationally slightly (as both flanges of a wheelset are never simultaneously in contact with both rails) even though it's nominally running in a straight line. If it hits a natural frequency (resonance) then it becomes unstable and - without the yaw damper - it's away, rapidly alternating between clockwise and anticlockwise rotations (about a vertical axis) causing high frequency shaking and vibration, known colloquially as 'hunting'. It was a phenomenon fully investigated by BR's research department as part of the APT programme.

 

As with all dampers (shock absorbers) the yaw damper will effectively lock up when subject to such rapid movement and thus minimise the vibrations - but at the expense of transmitting that high frequency load into the vehicle body via the yaw damper bracket.

 

There you go. Apologies to any on here who already know all that. For those who have experience of design loads in other fields may be of interest? I've labelled up all the other basic suspension elements - it's a 'trailing arm' suspension system. There also looks to be some form of torsion bar arrangement but I'll have to confess I don't have so much experience of them in railway applications.

Edited May 13, 2021 by LNER4479

[Gibbo675]

40 minutes ago, LNER4479 said:

No - it is the dark coloured casting, like so:

 

The whole thing I've outlined in red is the yaw damper bracket. Its role is to transfer the load from the yaw damper into the body structure, thereby dissipating the load.

 

The load I'm talking about is that which comes about from rapid oscillation of the bogie as it reacts to forces whilst travelling along. It shouldn't happen - but it does. Although it's designed to run in a perfect straight line (using the opposed cones effect of the wheelsets - conicity), it's actually reacting all the time to tiny variations in track geometry and can oscillate rotationally slightly (as both flanges of a wheelset are never simultaneously in contact with both rails) even though it's nominally running in a straight line. If it hits a natural frequency (resonance) then it becomes unstable and - without the yaw damper - it's away, rapidly alternating between clockwise and anticlockwise rotations (about a vertical axis) causing high frequency shaking and vibration, known colloquially as 'hunting'. It was a phenomenon fully investigated by BR's research department as part of the APT programme.

 

As with all dampers (shock absorbers) the yaw damper will effectively lock up when subject to such rapid movement and thus minimise the vibrations - but at the expense of transmitting that high frequency load into the vehicle body via the yaw damper bracket.

 

There you go. Apologies to any on here who already know all that. For those who have experience of design loads in other fields may be of interest? I've labelled up all the other basic suspension elements - it's a 'trailing arm' suspension system. There also looks to be some form of torsion bar arrangement but I'll have to confess I don't have so much experience of them in railway applications.

Hi There,

 

My motorbike has got a yaw damper for similar reasons, those being high frequency oscillations when the front tyre is only just making contact with the road surface under acceleration nullifying the effect of the castor angle:

 

 

I made the components from aluminium and then TIG welded it all together, what was I thinking !!!

 

Gibbo.

[rodent279]

So, if I read that correctly, the hunting, the rotational oscillation of the bogie, will cause forces to be transmitted through the yaw damper bracket to the body. Those forces will be applied largely in a fore and aft sense, a turning moment, so the yaw damper is trying to turn the bracket about its fixing point to the body. That is causing stresses to be set up in one direction, then in the other, in the bracket mount, which had caused the cracks (fatigue flaws?).

[LNER4479]

Yup - pretty much. In the previous cases in the UK, either the bracket itself fractures or it fails at the mounting point on the body (as we saw on here some pages back).

[rodent279]

So going back to TSI's, I can't see how this is a TSI problem. If the widget is designed such that it is compliant with the TSI, but exceeds it in order to meet local conditions, I can't see how that would be illegal.

We're all still speculating, which is dangerous territory, but if it's the case that the thing is compliant with the TSI, but not "man enough" for the job, then it sounds to me like either those responsible for the design didn't appreciate that it needed to be tougher, or those responsible for the procurement spec didn't, and simply insisted on compliance with the TSI. Or both.

Alternatively, the design is compliment with the relevant TSI's, and "man enough" for the local conditions, but some manufacturing flaw or defect has occurred.

 

[Pandora]

3 hours ago, boxbrownie said:

It looked to be the part of the box section to which the yaw damper is bolted, not at the lifting pad end.

I hope the engineers picked the correct length and stroke of the damper,  if the carriage has to negotiate a very sharp curve, eg depot sidings,  and the damper reaches a position of maximum or minimum stroke, the yaw damper bracket will be subjected to a large force

Edited May 13, 2021 by Pandora

[Pandora]

55 minutes ago, Gibbo675 said:

Hi There,

 

My motorbike has got a yaw damper for similar reasons, those being high frequency oscillations when the front tyre is only just making contact with the road surface under acceleration nullifying the effect of the castor angle:

 

 

I made the components from aluminium and then TIG welded it all together, what was I thinking !!!

 

Gibbo.

Norman Hossack front end, or is this a Britten?

Edited May 13, 2021 by Pandora

[rodent279]

This picture of the driving car of 800032 at Bristol in 2018 seems to show a slightly different design of bracket mount. Are the failures on any particular type of car?

[NIK]

Hi,

 

From the info provided including a diagram:

it looks as though the cracks have been discovered where a cantilever joins a cantilever at a change in section profile and then joins a cantilever at 90 degrees to it (assuming the part shown is a lift loading subframe and the body contributes little to the stiffness).

 

So instead of having one stress raiser (like the squarish corners of the De Havilland Comet Mk1 passenger windows) there seems to be three or four all joining around 9:30 O clock in the red circle.

 

Regards

 

Nick

[david.hill64]

1 hour ago, rodent279 said:

So going back to TSI's, I can't see how this is a TSI problem. If the widget is designed such that it is compliant with the TSI, but exceeds it in order to meet local conditions, I can't see how that would be illegal.

We're all still speculating, which is dangerous territory, but if it's the case that the thing is compliant with the TSI, but not "man enough" for the job, then it sounds to me like either those responsible for the design didn't appreciate that it needed to be tougher, or those responsible for the procurement spec didn't, and simply insisted on compliance with the TSI. Or both.

Alternatively, the design is compliment with the relevant TSI's, and "man enough" for the local conditions, but some manufacturing flaw or defect has occurred.

 

Designing something that exceeds the requirement of a TSI is not illegal.

 

Having a procurement specification that requires compliance with something more restrictive or better than the TSI is illegal unless a derogation exists.

 

The vehicle acceptance process is done by a Notified Body (NoBo), which checks compliance with the TSI's and a Designated Body which checks compliance with any National Notified Technical Rules that are still in force. The NoBo can only assert that the requirements of the TSI and its subordinate EN's have been met. It doesn't have any flexibility to say that 'although your design complies with the standard we think it ought to be better'.

 

Given that the cracks are apparently in the base metal, and not in the welds, then provided the base metal is what it should be, then I think we can say it is not a manufacturing defect (for the 800s).

[St Enodoc]

3 hours ago, LNER4479 said:

There also looks to be some form of torsion bar arrangement but I'll have to confess I don't have so much experience of them in railway applications.

I think you're referring to the anti-roll bar, Graham, which in layman's terms stops the body rolling from side to side on the secondary suspension (air bags).

[cheesysmith]

Technical question, are the bogies fitted with the centre bolster/pinnion (cannot remember the term, it is the piece that projects downward from the body that the bogie rotates around)? Asking because the bogies used under the latest Siemens units don't.

 

Off the wall idea, can  get the bogies off the BREL built EMU going for scrap me fit the T4 bogies under these IEP? Might finally cure the ride.

[Philou]

Hello chaps,

 

Even though I live miles away from any UK railway line, I've been following this with great interest. The good news, according to Realtime Trains, is that at least two GWR units left Swansea on time this morning London-bound at 0528 and 0628, though the first one had picked up a 7 minute delay in the Bridgend area - not specified why.

 

Swansea-bound, the first to leave was going via Bristol TM - I don't know if this is 'normal', but the second service (already left as I write this) is booked via Bristol Parkway.

 

I don't know if all the GWR 80X services will be up and running today.

 

Cheers,

 

Philip

Edited May 14, 2021 by Philou

[Dunsignalling]

31 minutes ago, Philou said:

 

 

I don't know if all the GWR 80X services will be up and running today.

 

Cheers,

 

Philip

Hi Philip,

 

Unfortunately, they won't. The GW announcement yesterday stated they are only anticipating getting two thirds of the fleet back in action by the end of next week, so a reduced timetable will be in force for some while yet.

 

John

[Bernard Lamb]

12 hours ago, boxbrownie said:

Upon my Uncles passing the procession passed by the factory and his work mates turned out to pay their respects.....very touching.

That was the usual way things were done.

Send me his name by PM if you like and I will probably be able to remember him.

Bernard

[rodent279]

Well it's an ill wind..... I've just read about FSW on Wikipedia. Fascinating stuff, I've learnt something today.

[woodenhead]

1 hour ago, Dunsignalling said:

Hi Philip,

 

Unfortunately, they won't. The GW announcement yesterday stated they are only anticipating getting two thirds of the fleet back in action by the end of next week, so a reduced timetable will be in force for some while yet.

 

John

Two thirds wont be bad - 66%, what is the contracted availability rate because the difference between that and the actual numbers will be key to how many services they have to cut.

 

The other question is whether 66% is the available to use number or that is the number of units fit to run and then maintenance has to be removed from that number too.

 

But at least there are trains

[Gilbert]

11 minutes ago, woodenhead said:

But at least there are trains

Todays Bristol & Swindon HSTs if anyone is interested

 

43239 + XC04 41026 45004 42375 42369 42051 42366 44012 + 43303
1Z14 05:34 Plymouth to Swindon
1Z15 09:29 Swindon to Bristol Temple Meads
1Z16 10:30 Bristol Temple Meads to Swindon
1Z17 11:29 Swindon to Bristol Temple Meads
1V50 12:45 Bristol TM to Plymouth
1E63 15:27 Plymouth to Leeds


43378 + XC02 41194 45002 42367 42037 42234 42371 44072 + 43304
1V50 06:06 Edinburgh to Bristol TM
1Z20 12:30 Bristol Temple Meads to Swindon
1Z21 13:29 Swindon to Bristol Temple Meads
1Z24 14:30 Bristol Temple Meads to Swindon
1Z25 15:29 Swindon to Bristol Temple Meads
1Z28 16:30 Bristol Temple Meads to Swindon
1Z29 17:33 Swindon to Bristol Temple Meads
1Z32 18:30 Bristol Temple Meads to Swindon
1Z33 19:30 Swindon to Plymouth

[APOLLO]

11 hours ago, Gibbo675 said:

Hi There,

 

My motorbike has got a yaw damper for similar reasons, those being high frequency oscillations when the front tyre is only just making contact with the road surface under acceleration nullifying the effect of the castor angle:

 

 

I made the components from aluminium and then TIG welded it all together, what was I thinking !!!

 

Gibbo.

 

There's a job waiting for you at Hitachi !!

 

Brit15

[LNER4479]

8 hours ago, david.hill64 said:

The vehicle acceptance process is done by a Notified Body (NoBo), which checks compliance with the TSI's and a Designated Body which checks compliance with any National Notified Technical Rules that are still in force. The NoBo can only assert that the requirements of the TSI and its subordinate EN's have been met. It doesn't have any flexibility to say that 'although your design complies with the standard we think it ought to be better'.

 

Indeed. Reassurance in one sense (as some have been querying) that there is still a process of independent scrutiny - but only within the scope of accreditation of the NoBo/DeBo.

 

Of course, there is also the possibility that there has been the application of the Common Safety Method for Risk Evaluation and Assessment, with independent review by the Assessment Body (AsBo) ...

[boxbrownie]

12 hours ago, LNER4479 said:

No - it is the dark coloured casting, like so:

 

The whole thing I've outlined in red is the yaw damper bracket. Its role is to transfer the load from the yaw damper into the body structure, thereby dissipating the load.

Yes I understand which bit is what, which is why I stated it looked to be the section of the box section (which I circled in red) to which the damper bracket is bolted.

It was a quick few seconds shown on TV but it certainly was not the damper bracket that was shown to have a fault, it appeared to be the other end of the box section of which one end is the lifting pad and the other the attachment point for the damper bracket.

[boxbrownie]

11 hours ago, Pandora said:

I hope the engineers picked the correct length and stroke of the damper,  if the carriage has to negotiate a very sharp curve, eg depot sidings,  and the damper reaches a position of maximum or minimum stroke, the yaw damper bracket will be subjected to a large force

Certainly hope so, that is basic suspension geometry, make sure the damper has a stroke which is slightly more than the maximum working moment of the design.

 

If they got that wrong no wonder the seats are so bad as well (JMO of course) 

 

 

Edited May 14, 2021 by boxbrownie

[boxbrownie]

10 hours ago, NIK said:

Hi,

 

From the info provided including a diagram:

it looks as though the cracks have been discovered where a cantilever joins a cantilever at a change in section profile and then joins a cantilever at 90 degrees to it (assuming the part shown is a lift loading subframe and the body contributes little to the stiffness).

 

So instead of having one stress raiser (like the squarish corners of the De Havilland Comet Mk1 passenger windows) there seems to be three or four all joining around 9:30 O clock in the red circle.

 

Regards

 

Nick

The thing that puzzled me when that drawing was first released is the red areas in each picture seem to be different parts of the box section, diagram 1 appears to highlight the damper bracket support section of the component, where as diagram 2 appears to highlight what I take to be the lifting pad area.....which is the opposite end.

[Mike_Walker]

12 hours ago, rodent279 said:

This picture of the driving car of 800032 at Bristol in 2018 seems to show a slightly different design of bracket mount. Are the failures on any particular type of car?

As I understand it, the vast majority if not all of the problems have been found on the non-driving vehicles.  Of the original yaw-damper cracks, all were above the motor not trailer bogies although I don't know if this holds true for the jacking point problem.