Hitachi trains grounded

[LNER4479]

1 hour ago, Bucoops said:

Not really. Every unit will need checking, and they have presumably been doing this through the night to get units back into service as soon as possible, but even when they are cleared for use, they will be in the wrong place, train crew hours might be an issue and so on. It's a complete mess so the do not travel advice is spot on.

 

As someone else has already said, just like we used to do on BR, 30 and more years ago. An overnight emergency safety check after a new / unusual fault has been found. All but essential maintenance suspended and technical staff diverted on to inspecting the suspect area on each vehicle, reporting back to 'Control' on a hastily devised special check form. A handful of vehicles stopped pending further attention and the rest gradually released back out into service. Easier with LHCS as you could replace individual vehicles in a set or run short-formed.

 

1 hour ago, Jol Wilkinson said:

Surely this can't be correct. Japanese design and engineering, what has gone wrong?

But designed to run on Japanese maintained track. From what I'm hearing re yaw dampers that is another classic, perennial old favourite (I seem to recall Cl.158s suffered from the same thing upon their introduction). Aren't the CAF 190s similarly affected at the moment?

 

In which case it's all to do with vehicle-track interaction, a complex subject at the best of times. High frequency vibration inputs from how the bogie rides on the track is transmitted into the vehicle. The yaw damper is there is prevent excessive vibration but all that energy has got to go somewhere. It's all predicted with computer modelling (Vampire) prior to build but the real proof is only in the eating. I think I'm right in saying that the similar Hitachi trains on HS1 didn't ride as well as had been predicted although I'm not sure what the eventual solution to that was. No doubt a longer-term fix will be required for these trains similarly.

Edited May 8, 2021 by LNER4479

[Kris]

2 minutes ago, TomScrut said:

 

To see some of the negative comments on Facebook about these trains you'd have thought the BR locos, coaches and units were perfect.

The sky is always blue and the sea always warm on social media posts. In the same was, the past was always perfect didn't you know...  

[APOLLO]

New modern stock that I've been on seems to lurch and bang alarmingly on point work (Class 195 EMU especially). I've read on here the Hitachi trains give a similar rough ride, though I've never been on one. Pendolinos always seem smooth though, but they're getting on a bit now.

 

Back to the drawing board re suspension etc ?

 

Brit15

[Mike_Walker]

The units which have been found defective so far are the earliest Class 800s on GWR which have accumulated the highest mileages since entering service.  However, the nature of the defect, a metal fatigue fracture in the weld which joins the bolster carrying the yaw damper attachment and jacking point to the main body structure (see below), means that it can be expected to show up across the entire 80x fleet operated by GWR, LNER, TPE and HT as their mileages increase.

 

 

I discussed the problem a week ago with Mark Hopwood, GWR's MD and a long-standing personal friend, and at that time only a handful of cracks had been discovered and two or three units stopped for repair.  The cracks found at that time were above the motor not trailer bogies which is understandable given the higher stress they are subjected too.  Although concerned, he was of the opinion at that time that the issue was manageable and nowhere as serious as the problems involving the CAF built trains.  Obviously, things have moved on and it would appear further cracks have been discovered.  I haven't attempted to contact Mark for an update this morning as I figure he's probably more than a tad busy right now!

 

The entire fleet is currently undergoing checks at the various Hitachi depots and units given a clean bill of health are being allowed to return to service which is why, as I type this, limited services are returning to GWR and LNER.  Hopefully enough units will be released over the weekend to allow a near "normal" service to operate next week.  If a number of additional problems do emerge then there could be problems resourcing operations when services ramp up from May 17.

 

Repairs will not be easy.  The 80x have aluminium bodies and aluminium is more difficult to weld than steel.  It needs much higher degrees of heat and the material transmits this very effectively to places you really don't want it.  Like all modern trains, the 80x cars are stuffed full of sensitive electronics controlling everything from the train's performance to seat reservations and working the loo doors.  If subjected to large amounts of heat these component will fry and therefore before any welding can take place many of them will need to be removed.  Then once the weld repair has been completed and tested they will have to be refitted and themselves tested.  This could easily take one or two days per car whilst the weld repair itself might only take a hour or so.  And remember, there are 4 locations per car and the fleet numbers in excess of 1000 vehicles.

 

As noted by others, problems with yaw damper attachments are nothing new and have been cropping up ever since they first started being used - the Class 158s probably being  the most high profile case.  It is a high stress area which requires both very careful initial design and subsequent manufacture.  It's not always easy to get it right.

 

Meanwhile over a CAF...  The problem there is somewhat different.  It revolves around the design of the yaw damper attachment to the body which uses bolts in tee slots which are part of an extrusion attached to the body.  In one case, this assembly was torn way from the body and signs of the same problem potentially affecting other units led to at least 22 Class 195 DMUs and Class 331 EMUs being stopped.  The identical design is used on all the current CAF built trains in the UK, Classes 195 196, 197, 331 and 397 plus the Mk5 and Mk5s LHCS.

 

 

 

 

[Oldddudders]

10 minutes ago, Kris said:

The sky is always blue and the sea always warm on social media posts. In the same was, the past was always perfect didn't you know...  

And anoraks loved HSTs! I have been more than happy with the ride and comfort levels on the GWR 8xxs. 

 

I am sure, and certainly hope, this is a temporary blip and engineering will triumph as it almost always does. 

[Peter Kazmierczak]

Does the problem appear on the SE Javelins units too?

[TomScrut]

2 minutes ago, Oldddudders said:

And anoraks loved HSTs!

 

Whilst I wasn't alive at the time I expect that they caused a stir when they came about, replacing big locos all over the country in a similar way to what the 80Xs have with the HST/91s.

[Peter Kazmierczak]

Even our beloved "Thousands" had to be stopped for checking cracks, back in the 60s. And before that the "Kings"... 
Just add your favourite loco class to the list.

[Mike_Walker]

1 minute ago, Peter Kazmierczak said:

Even our beloved "Thousands" had to be stopped for checking cracks, back in the 60s. And before that the "Kings"... 
Just add your favourite loco class to the list.

Agreed, but back then the affected locos/units amounted to only a small part of the fleet and could be covered by other types.  No so today regrettably.

[Nearholmer]

Is that attachment plate/bracket welded to the skin of the car-body?

[SHMD]

5 minutes ago, Nearholmer said:

Is that attachment plate/bracket welded to the skin of the car-body?

...according to some reports, it was attached using cellulose and saliva product!

 

 

Kev.

[Mike_Walker]

6 minutes ago, Nearholmer said:

Is that attachment plate/bracket welded to the skin of the car-body?

As I understand it, it is a large unit which goes completely across the underside of the body.  The body itself is constructed from extrusions not a framework with a skin applied.

[PenrithBeacon]

Love the title of the thread! One of my complaints about the modern railway scene is the the d/emus too often look like airliner fuselages adapted for rails. All very boring.

I'm surprised by the blanket ban as the early builds should have the problem to a greater extent than the more recent ones. It wouldn't surprise me if a the eventual solution wasn't a redesign and change out the affected sub-assembly, though, rather than a welding jobby

To those who wish to make unpleasant remarks about Japanese engineering, perhaps the best counter is to remind them of the difficulties that Boeing have recently gone through amongst other engineering firms over the years.

[Ian Hargrave]

A week ago,passsing Neville Hill on a northbound XC 220,I espied a job lot of MkIV and Class91 in storage...and wondered why they hadn’t yet met the cutter’s torch. Maybe it was a premonition  ? My thoughts go out to TOC personnel and poor suffering travelling public alike.We’ve all had a lot to endure lately. 
 

In the 1950’s,when Mr.Bulleid’s MN’s suffered an enforced temporary withdrawal,their place was quickly taken up by motive power supplied by other BR regions. No such quick fix is currently available and it looks as if XC ....somewhat overcrowded ( if social distancing will permit ).....will have the ECML....mainly to themselves 

 

 

 

 

 

[boxbrownie]

4 hours ago, great central said:

WNXX as well as internal sources.

News is notoriously slow to catch up with some things, remember there's elections going on and well as other things on people's minds.

It was on the BBC TV news at 08:00 this morning.....they stated massive delays due to the 800 fleet having cracks in the “running gear” I believe they said.

[jim.snowdon]

It's one of those known problems in rolling stock design, and one of those areas that has to be very carefully defined in the procurement specification. The risk is that the track, whose condition is outside the control of both the vehicle designer and the maintainer, does not meet the specification. Then, it ends up with the lawyers. Hitachi, I have no doubt, will be looking to prove that the fault lay with the DfT in their specification, followed by arguments between the DfT and Network Rail over the veracity of the information. All that is certain is that the lawyers will be happy.

 

Jim

[Hobby]

2 hours ago, Bucoops said:

Don't envy the customer service staff of the affected TOCs...

 

The ones most likely to get it in the neck are the on board staff of the TOCs still running trains over affected lines, mainly our lot, Cross Country. We were already seeing numbers go up considerably in the NE, I worked several trains close to and over the limit we recommend for social distancing two Saturdays ago, even with 8 or 9 on. Now we're going to get dumped with all LNER and TPE passengers it'll be hell. Not to mention our SW trains south of Cheltenham. Glad I've got the weekend off!

Edited May 8, 2021 by Hobby

[Nearholmer]

Something as subtle as a minor difference in yaw-damper response from assumptions could mess all this up, leaving aside assumptions around track condition, which as JS says are prime suspects.

 

The bracket- thingy is pretty long, so the turning moment on that weld will be impressive.

[MJI]

This makes me think of this.

 

How did BR get it so right with Mark 3 and BT10?

[Hobby]

Didn't the Mk3s have brake smell problems?

[Fat Controller]

2 minutes ago, Hobby said:

Didn't the Mk3s have brake smell problems?

Yes, a very strong 'fishy' smell whenever brakes were applied. They also had sometimes less-than-reliable HVAC, as well as cooling-group problems; it was common to see coolant bowsers stabled on platforms.

[TheSignalEngineer]

2 minutes ago, Fat Controller said:

. They also had sometimes less-than-reliable HVAC, as well as cooling-group problems; it was common to see coolant bowsers stabled on platforms

Lickey was always a problem. HSTs frequently arrived at New Street on one engine if the coolant was already a bit low as the slopping around in the tank when it hit the bank at speed led to the sensor being uncovered for long enough to raise a critical alarm. Conversely the other power car could appear overfilled if it had been topped up before leaving Bristol.

 

[caradoc]

3 hours ago, great central said:

There's these, recently parked up at Ely, some trailers at the back of the site as well. 

All it would need is a few drivers and guards to come and pick them up

 

 

Providing traincrew with the necessary combination of route and traction knowledge might be a problem however !

 

Withdrawing an entire fleet is not unprecedented; The EMUs which served my local line until around 2001, the AM3/303 sets, were withdrawn, not long after their introduction, en masse after some exploded ! 

 

Hopefully inspection of the 80x fleet will be carried out quickly so that this disruption is short lived, and in the longer term a permanent engineering solution found. 

 

 

[APOLLO]

1 hour ago, PenrithBeacon said:

 

To those who wish to make unpleasant remarks about Japanese engineering, perhaps the best counter is to remind them of the difficulties that Boeing have recently gone through amongst other engineering firms over the years.

 

Yes Boeing have serious problems with the "Pickle Forks" on 737's - a complex aluminium structure that connects the wings to the body.

 

https://www.engineering.com/story/cracks-found-on-boeings-737-ng-pickle-forks

 

The 787 Dreamliner also has body section alignment problems, something to do with shims. Both are VERY expensive strip down & repair / replace problems.

 

https://aviationweek.com/air-transport/safety-ops-regulation/new-787-problems-spotlight-boeings-quality-issues

 

These types of problems are not new, and have engineering fixes, but at cost. Better to find & fix such problems be it trains or planes before something serious happens, like the 737 Max disasters. Ongoing close inspection is the key.

 

Brit15

 

 

[jim.snowdon]

31 minutes ago, Nearholmer said:

Something as subtle as a minor difference in yaw-damper response from assumptions could mess all this up, leaving aside assumptions around track condition, which as JS says are prime suspects.

 

The bracket- thingy is pretty long, so the turning moment on that weld will be impressive.

The dynamic behaviour of bogies is a complex subject, particularly at high speeds. The basic problem is that every bogie has a critical speed, determined by such factors as the yaw stiffness of the primary suspension, the tyre profile (in practice the conicity and how that changes with displacement of the wheelset in the gauge), the rail head profile, the yaw stiffness of the bogie relative to the car body. The yaw damper is a critical element in keeping the critical speed, when the bogie will go into a sustained oscillation, ie hunting, above the working speed of the train. The penalty is that, in doing that, the yaw damper is subjected to continuous oscillating forces from the bogie, which makes it and its attachment to the car body prime candidates for fatigue cracking. Having an aluminium car body does not help, as it generally has a lower resistance to fatigue cracking than steel, nor does any tendency to design out conservative engineering. Hitachi are not the first to have found that out the hard way.

 

It does not help that trains have a habit of wearing in, as it were. Rubber suspensions change with age, as was all too evident on some London Underground stock. Tyre and rail profiles change with time, sometimes in none too obvious ways when a particular rolling stock is dominant on individual tracks. Exactly how tyre profiles change over time is not entirely predictable. All of these things are sent to try the designer and resolving them sometimes relies on experience and a degree of intuition. It doesn't always work, as I know from experience.