Northern withdraws some CAF trains due to yaw bracket failures

JModulo

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I see that some 195's have now been temporarily withdrawn following the yaw dampers snapping off from the body mounts.
 
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dk1

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I see that some 195's have now been temporarily withdrawn following the yaw dampers snapping off from the body mounts.
22 units according to another post on another site. All other units have passed their inspection.
 

superkev

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I see that some 195's have now been temporarily withdrawn following the yaw dampers snapping off from the body mounts.
Re yaw damper brackets failing apparently one may have become completely detached. Cant say I'm surprised giving the poor ride and the bangs and crashes coming from the underside of these units. Wonder if the similar 331s and 397s are affected.
I'm old enough to remember an identical problem with the 158s when new which resulted in more substantial yaw damper mounting brackets bein fitted. Major work.
K
 
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skyhigh

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Re yaw damper brackets failing apparently one may have become completely detached. Cant say I'm surprised giving the poor ride and the bangs and crashes coming from the underside of these units. Wonder if the similar 331s and 397s are affected.
I'm old enough to remember an identical problem with the 158s when new which resulted in more substantial yaw damper mounting brackets bein fitted. Major work.
K
Apparently that picture was taken after a deliberate attempt to apply additional force to see what the result was, and nothing has failed in service.
 

Geeves

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It was posted on here that someone somewhere specified that even with deflated suspension the train should still be able to run at 65mph, instead of the usual low speed (back to the depot) of 2nd gen units. That's one of the reasons why the ride is so rough. Its just riding on the stops all day long, bang, crash, bang. I am wondering if this has lead to undue stress on the suspension components?
 

Efini92

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It was posted on here that someone somewhere specified that even with deflated suspension the train should still be able to run at 65mph, instead of the usual low speed (back to the depot) of 2nd gen units. That's one of the reasons why the ride is so rough. Its just riding on the stops all day long, bang, crash, bang. I am wondering if this has lead to undue stress on the suspension components?
The sprinters could run at 75mph with deflated air suspension providing there was no passengers in the affected vehicle.
I think modern bogies just aren’t design to run on our Victorian infrastructure.
 

Watershed

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Oh dear... (article from Railway Gazette)
A significant number of CAF multiple units operated by Northern were taken out of service at the beginning of April after the failure of a yaw damper. Sections of the vehicle’s structure were broken away completely in the incident.

An urgent National Incident Report issued by RSSB on April 3 explained that a yaw damper mounting bracket had detached from the body on vehicle 102121 of Class 195 DMU 195 121

...

I understand there were (are?) various shortforms as a result. Running Blackpool-Manchester Airport/Hazel Grove services using double 331s is proving rather fortuitous right now!
 

D6130

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This has already been covered in at least two other threads and certainly does not show CAF products in a very good light. I would imagine that urgent safety checks will also have been carried out on the Caledonian Sleeper and TPE Mark 5 loco-hauled stock.
 

hexagon789

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I found a photo on Twitter of a unit with the yaw damper detached - looks like the mounting has effectively snapped off?

BF153782-2725-4244-8695-767C213D813E.jpeg-1.jpg
 

hexagon789

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Could somebody possibly explain what a yaw damper does (and broadly where on the unit it is found)?
Controls bogie movements preventing hunting and oscillations affecting ride quality at speed (though with certain modern bogie designs it's debatable whether there's any ride quality to start with!).

It's essentially a long damper which links between the body and bogie adding rotational stiffness to the bogie movements.
 

Wolfie

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I see that some 195's have now been temporarily withdrawn following the yaw dampers snapping off from the body mounts.
Woeful considering their age. When you look at the 332 and 333 issues too a pattern seems to emerge.... The new Ansaldo Breda? Makes you wonder if CAF should be avoided like the plague in future procurements....
 

hexagon789

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Woeful considering their age. When you look at the 332 and 333 issues too a pattern seems to emerge.... The new Ansaldo Breda? Makes you wonder if CAF should be avoided like the plague in future procurements....
The issues with CAF are well-known throughout the railway industry in Britain and in Europe - yet products are still bought from them.
 

py_megapixel

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The issues with CAF are well-known throughout the railway industry in Britain and in Europe - yet products are still bought from them.

<cynicism>
Stadler were the only other company willing to bid DMUs, and they're known for being quite expensive
</cynicism>
 

robbeech

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I think modern bogies just aren’t design to run on our Victorian infrastructure.
If this is the case, given that Victorian Infrastructure is what we have, would it not have been wiser to have designed bogies that WERE able to run on it?
 

fgwrich

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Makes you wonder though if everyone else is checking their inside frame bogie designs at the moment too, eg Hitachi? (The Siemens SF-7000 uses a different, lighter style of Yaw Damper).
 

Bletchleyite

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Makes you wonder though if everyone else is checking their inside frame bogie designs at the moment too, eg Hitachi? (The Siemens SF-7000 uses a different, lighter style of Yaw Damper).

Doesn't look like a damper issue - looks to me like the bit of the body that it was bolted to broke off. That is very concerning, because it could potentially also mean the body is not strong enough for the specified crashworthiness?
 

millemille

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Doesn't look like a damper issue - looks to me like the bit of the body that it was bolted to broke off. That is very concerning, because it could potentially also mean the body is not strong enough for the specified crashworthiness?
The reaction arm for the yaw damper is attached to the vehicle body by tapping blocks in T-slots in the vehicle sole bar. The T-slots have failed locally to the tapping blocks. It's a big leap to make from T-slot failure to whole vehicle structure and crash worthiness...
 

Wolfie

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The reaction arm for the yaw damper is attached to the vehicle body by tapping blocks in T-slots in the vehicle sole bar. The T-slots have failed locally to the tapping blocks. It's a big leap to make from T-slot failure to whole vehicle structure and crash worthiness...
The interesting question is whether the failure is due to poor design, material failure or poor quality control. None of those are great but some are potentially much more concerning than others.
 

millemille

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The interesting question is whether the failure is due to poor design, material failure or poor quality control. None of those are great but some are potentially much more concerning than others.

Or, how about looking at it the other way? The processes the industry has in place have worked exactly as they should and have found the failure before an accident occurred, other operators have been notified, the fleet has been checked and immediate risk has been contained and now cause can be determined and counter measures put in place...

Problems like this happen all the time across the industry, and have done for years and will continue to do so for years, and the measure of the organisations involved is how they address it.
 

LOL The Irony

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I found a photo on Twitter of a unit with the yaw damper detached - looks like the mounting has effectively snapped off?

View attachment 94035
That's actually taken a bit of the frame with it as well. Not good at all. I wonder if there's scope for the DfT to sue CAF for the poor quality. I just hope they have a lifetime guarantee or maintenance contract...
 

hexagon789

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<cynicism>
Stadler were the only other company willing to bid DMUs, and they're known for being quite expensive
</cynicism>
But sturdier - not perfect but you get what you pay for...

That does not look like a quick fix.
No

If this is the case, given that Victorian Infrastructure is what we have, would it not have been wiser to have designed bogies that WERE able to run on it?
I would say so, might even get decent ride quality again

Makes you wonder though if everyone else is checking their inside frame bogie designs at the moment too, eg Hitachi? (The Siemens SF-7000 uses a different, lighter style of Yaw Damper).
It's not the dampers themselves

Doesn't look like a damper issue - looks to me like the bit of the body that it was bolted to broke off. That is very concerning, because it could potentially also mean the body is not strong enough for the specified crashworthiness?
Correct, it's the T-slot mounting/attachment point

The reaction arm for the yaw damper is attached to the vehicle body by tapping blocks in T-slots in the vehicle sole bar. The T-slots have failed locally to the tapping blocks. It's a big leap to make from T-slot failure to whole vehicle structure and crash worthiness...
I understand they think it's the stresses not being spread into the bodyside effectively and instead being concentrated in a few overstressed points

That's actually taken a bit of the frame with it as well. Not good at all. I wonder if there's scope for the DfT to sue CAF for the poor quality. I just hope they have a lifetime guarantee or maintenance contract...
Possibly, I certainly would be looking to see what actions can be taken
 

millemille

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I understand they think it's the stresses not being spread into the bodyside effectively and instead being concentrated in a few overstressed points
I design underframe equipment rafts which hang from T-slots and my initial reaction on seeing the NIR and the photo's was to think the tapping blocks looked short for the application, given that the ones we tend to use - which are not subject to reaction forces like a damper mount - are always significantly longer (Space and insertion slot allowing) than the clamping face of the attached raft.
 

LOL The Irony

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Stadler were the only other company willing to bid DMUs, and they're known for being quite expensive
I believe another problem was their diesel range not being as good as CAFs, which would lead to issues on the long distances the 195s are expected to travel, which partially influenced Arriva's decision to go with CAF. Siemens, Alstom and Bombardier not offering a diesel train hasn't helped matters either.
Possibly, I certainly would be looking to see what actions can be taken
It needs to happen, the Civitys are becoming the new Junipers and will probably require a very expensive rebuild very shortly. All I say is I hope someone kept the receipt.
 

hexagon789

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I design underframe equipment rafts which hang from T-slots and my initial reaction on seeing the NIR and the photo's was to think the tapping blocks looked short for the application, given that the ones we tend to use - which are not subject to reaction forces like a damper mount - are always significantly longer (Space and insertion slot allowing) than the clamping face of the attached raft.
So the fact they are shorter could lead to them being greatly overstressed?


It needs to happen, the Civitys are becoming the new Junipers and will probably require a very expensive rebuild very shortly. All I say is I hope someone kept the receipt.
Undoubtedly, there has to be either a fix at CAF's expense or some other repercussions. You would hope such things were specified in the contract.
 

hwl

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I design underframe equipment rafts which hang from T-slots and my initial reaction on seeing the NIR and the photo's was to think the tapping blocks looked short for the application, given that the ones we tend to use - which are not subject to reaction forces like a damper mount - are always significantly longer (Space and insertion slot allowing) than the clamping face of the attached raft.
Agreed, comparatively very little material and very high stresses in this case. Worryingly little material need to fail before total failure is inevitable.

So the fact they are shorter could lead to them being greatly overstressed?
Yes and the slotted design also means very little resistance to rotational forces in the vertical plane
 

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