Transport for Wales 769's

swt_passenger

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There was a thread a few years ago where transformer weights and ballasts in lieu were discussed, and it basically came down to DC Electrostars all had ballast weights in place of transformers, and DC Desiros didn’t.

I think the only possible conclusion that can be drawn is that Bombardier and Siemens have different approaches to engineering, and there is no standard rule...
 
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aleggatta

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28 Sep 2015
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There was a thread a few years ago where transformer weights and ballasts in lieu were discussed, and it basically came down to DC Electrostars all had ballast weights in place of transformers, and DC Desiros didn’t.

I think the only possible conclusion that can be drawn is that Bombardier and Siemens have different approaches to engineering, and there is no standard rule...
All DC only electrostars are part of a class that also has dual voltage varients and had ballast as they needed to have the same braking characteristics as the dual voltage versions, there are no dual voltage 450s so the ballast is not required on this class.
 

Adlee Turner

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6 Nov 2018
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I think it’s the fifth unit to be delivered to Cardiff? I’m sure the units delivered are 769002/003/006/008/452. With 769008 the only one making it to Rhymney and back. There is 4 more remaining 769s to be delivered and one of them is the last 769/0 to be delivered which is 769007. I believe it was sent to Doncaster Wabtec For attention, I’m not sure if it’s back at Loughborough yet. However, the remaining 769 are /4 but not sure of the numbers
 

supervc-10

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All DC only electrostars are part of a class that also has dual voltage varients and had ballast as they needed to have the same braking characteristics as the dual voltage versions, there are no dual voltage 450s so the ballast is not required on this class.
A dual voltage 450 is a 350/1, so there are equivalent units in the Desiro family. But I presume that braking characteristics have to be consistent across the class and therefore the 350 and 450 don't need to be the same.
Having said that, my understanding is that one of the reasons for the concrete block is for suspension tuning. I'd have also thought that in this day and age of computer control the manufacturer could make the braking profile consistent irregardless of the actual weight of the vehicle, suggesting that this is more Bombardier being cheap and Siemens going the extra mile...
 

aleggatta

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Having said that, my understanding is that one of the reasons for the concrete block is for suspension tuning. I'd have also thought that in this day and age of computer control the manufacturer could make the braking profile consistent irregardless of the actual weight of the vehicle, suggesting that this is more Bombardier being cheap and Siemens going the extra mile...
it's worth remembering, that the Electrostars were built at turn of the century, not this day and age, and they would have had 5-10 years development beforehand, and they would need to design things in the most reliable way when it comes to product selection circa 1993/5. Also, by and large unit suspension is rubber chevrons(primary) and the air bag type(secondary), and if there isn't the weight on the coach to counteract gravity and absorb any resonance you will start having issues with the coach leaving it's kinetic envelope, and that you can only solve with additional weight. something which I believe siemens dealt with by more evenly distributing equipment along the train, whereas Bombardier kept their modular design which had the bonus of ease of reformation in future and conversion to AC. Swings and roundabouts at the end of the day, and whilst it probably would be quite possible for the 769 vehicle profile to be put into modern computer modelling to look at removing the redundant AC equipment to save weight, I doubt the ROSCO would have any inclination to do so as it would limit the future use of the units should there be difficulty to re-instate all the AC equipment (take for example the removal of the DC equipment from the 365's leaving them as AC only units now due to loss of knowledge/equipment)
 

JN114

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28 Jun 2005
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That's mad. Why couldn't the whole train have been delivered in one piece to Canton by rail?
Presumably the other 3 carriages will have to come in separate journeys each by road now as well
Could be one of any number of perfectly logical reasons...
 

pompeyfan

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Perminantly Temporary is a bit of a railway thing nowerdays.
a bit like the TSR at Weybridge which appeared in last nights railway centre picture of the day. The picture is from 10 years ago, the TSR is still there.
 

Bob Price

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8 Aug 2019
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So, when are these 769’s actually going to enter service?
How long is a piece of string. They still aren't testing, despite the paths being in for them, some haven't even turned a wheel yet. I can't see them having passengers on them much before the new year at this rate.
 

py_megapixel

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5 Nov 2018
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Sorry if I'm missing something really obvious but where are these going to run under electric power? Northern have various electric sections in the Manchester and Leeds areas and Great Western have electrication on the eastern great western and on the south western mainline, but where on Wales and Borders is electric?
 

Energy

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Sorry if I'm missing something really obvious but where are these going to run under electric power? Northern have various electric sections in the Manchester and Leeds areas and Great Western have electrication on the eastern great western and on the south western mainline, but where on Wales and Borders is electric?
They don't have pantographs installed on the TfW units for that reason.
 

_toommm_

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Sorry if I'm missing something really obvious but where are these going to run under electric power? Northern have various electric sections in the Manchester and Leeds areas and Great Western have electrication on the eastern great western and on the south western mainline, but where on Wales and Borders is electric?
Electric power will be on the Southport to Alderley Edge route if that gets reinstated. The idea was electric from Alderley to Salford (I believe) then diesel to Southport.
 

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