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Transport for Wales 769's

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southern442

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When watching the videos, listening to the motor sounds I thought to myself that the acceleration was markedly worse than when they were 319s, as the motor sounds are much slower to increase in pitch. But watching the most recent video it seems as though they actually accelerate faster than the motor sounds would have you believe - has there been anything which has caused the speeding up sound to 'take longer' as it were?
 
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Bletchleyite

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When watching the videos, listening to the motor sounds I thought to myself that the acceleration was markedly worse than when they were 319s, as the motor sounds are much slower to increase in pitch. But watching the most recent video it seems as though they actually accelerate faster than the motor sounds would have you believe - has there been anything which has caused the speeding up sound to 'take longer' as it were?

That last video looks and sounds like a 319 on third rail, which I guess is what it basically is (give or take the power station and third rail being built in). They were always quicker off the mark on AC, though never sprightly.
 

Domh245

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When watching the videos, listening to the motor sounds I thought to myself that the acceleration was markedly worse than when they were 319s, as the motor sounds are much slower to increase in pitch. But watching the most recent video it seems as though they actually accelerate faster than the motor sounds would have you believe - has there been anything which has caused the speeding up sound to 'take longer' as it were?

Possibly a combination of better conditions (no longer leaf fall season) and more driver familiarity I would think than any actual modifications
 

samuelmorris

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It seems maybe slightly better in that video, but hard to judge from the outside. Worth noting they started off very slowly and then increased the power as they passed the camera. Knowing how the pitch of Mk3 EMU traction motors relates to top speed, on the assumption they haven't been regeared (and if they had, then it's even worse), it's taken 30 seconds for that unit to reach 20mph. That's still pretty weak, and I'd wager, still slower than what a 150 could achieve.
 

southern442

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Possibly a combination of better conditions (no longer leaf fall season) and more driver familiarity I would think than any actual modifications

It seems maybe slightly better in that video, but hard to judge from the outside. Worth noting they started off very slowly and then increased the power as they passed the camera. Knowing how the pitch of Mk3 EMU traction motors relates to top speed, on the assumption they haven't been regeared (and if they had, then it's even worse), it's taken 30 seconds for that unit to reach 20mph. That's still pretty weak, and I'd wager, still slower than what a 150 could achieve.

Watching the second video, it seems to me as though the motor sounds are still far too 'low' for the speed it appears to be going. Comparing with a 319/455 etc speeding up, the motor sounds will have gone up a few pitches by that speed.
 

AM9

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That last video looks and sounds like a 319 on third rail, which I guess is what it basically is (give or take the power station and third rail being built in). They were always quicker off the mark on AC, though never sprightly.
I don't think that there was much difference between 319s under OLE and on 3rd rail power as they weren't deliberately limited on DC like later generations e.g. Electrostars and Desiros where the software limited their maximum power draw to 50% or 60% of maximum.
 

Bikeman78

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That last video looks and sounds like a 319 on third rail, which I guess is what it basically is (give or take the power station and third rail being built in). They were always quicker off the mark on AC, though never sprightly.
I agree with AM9. I didn't notice much difference. It's all relative; clearly they are faster then CIG/VEPs (plenty of chances to compare on the four track railway around Gatwick Airport) but slower than 323s and 700s. They seemed nippy enough on the stoppers to Brighton, certainly much, much faster than a 769.
 

AM9

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Watching the second video, it seems to me as though the motor sounds are still far too 'low' for the speed it appears to be going. Comparing with a 319/455 etc speeding up, the motor sounds will have gone up a few pitches by that speed.
I'm not disagreeing on that observation, but let's see if we can arrive at an estimate at the motor speed:
Taking your youtube video of a Euston to Northampton 319 run:
This train on the WCML is unbridled by any linespeed restrictions, (I think that even the slows are 100mph) and over the stretch between Leyton Buzzard tunnel (41m:00s) and Bletchley Drayton Road Junction (44m:00s) the frequency pitch of the traction motor sound tops out at about 850Hz. There's not much scope for wheelslip so we can assume that the pitch is proportional to the linear speed along the track. If there are any regulars of the route who have been on 319s over this stretch, who might have clocked (or driven) and could confirm the likely speed, the pitch of the motor whine on the 769 videos can be used to a) confirm (or not) that there is no change to the gearing of the 769s and b) help arrive at a rough estimate of the speeds from the new videos including the times from starting, the sort of acceleration performance that the 769s are currently achieving.
 
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samuelmorris

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Possibly. There's a bit of variation either way due to the variance in wheel diameter as they wear, but having ridden on 321s on the GEML on a section limited to 90mph for many years, around 900Hz was the norm, so 85 for your video sounds about right.
 

AM9

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Possibly. There's a bit of variation either way due to the variance in wheel diameter as they wear, but having ridden on 321s on the GEML on a section limited to 90mph for many years, around 900Hz was the norm, so 85 for your video sounds about right.
OK, well just before 2m:50s on the 769 clip on post #1328, the pitch is just over 300Hz and the view out of the window doesn't look unlike 30mph.
 
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Bikeman78

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OK, well just before 2m:50s on the 769 clip on post #1328, the pitch is just over 300Hz and the view out of the window doesn't look unlike 30mph.
The clip is Llanishen to Lisavane and Thornhill. In my experience, a 769 will get to 30 mph on that journey before starting to brake.
 

Bald Rick

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I don't think that there was much difference between 319s under OLE and on 3rd rail power as they weren't deliberately limited on DC like later generations e.g. Electrostars and Desiros where the software limited their maximum power draw to 50% or 60% of maximum.

I agree with AM9. I didn't notice much difference. It's all relative; clearly they are faster then CIG/VEPs (plenty of chances to compare on the four track railway around Gatwick Airport) but slower than 323s and 700s. They seemed nippy enough on the stoppers to Brighton, certainly much, much faster than a 769.

They were definitely better on AC than DC. I offer no evidence other than I seem to remember an article in Modern Railways when they were new, which said that on AC the traction equipment could supply up to 1000v to the traction motors, but on D.C. they were limited to the [nominal) 750v. Clearly current comes into it as well of course!
 

Bikeman78

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They were definitely better on AC than DC. I offer no evidence other than I seem to remember an article in Modern Railways when they were new, which said that on AC the traction equipment could supply up to 1000v to the traction motors, but on D.C. they were limited to the [nominal) 750v. Clearly current comes into it as well of course!
I'm sure that the railway performance society could shed some light on the subject. I'll have a nose through the website.
 

AM9

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They were definitely better on AC than DC. I offer no evidence other than I seem to remember an article in Modern Railways when they were new, which said that on AC the traction equipment could supply up to 1000v to the traction motors, but on D.C. they were limited to the [nominal) 750v. Clearly current comes into it as well of course!
You may be correct in absolute terms as the MML clearly has a better power supply in terms of available power most of the time, whereas the BML suffers every time two or three long trains take as much as they are permitted in the same locality and the edge goes off the performance, however the 319's 315BZ motors are only uprated GEC versions of the standard EE507 series DC design, and their power rating would be at 750V nominal. If they are offered much over that, the traction electronics would I suggest, limit the current drawn (or the amount of weak field applied at speed) to stay withing the 1 hour rating. Do they have a higher overload rating for acceleration purposes?
The other issue is that the MML linespeeds would allow electric traction to open up almost as soon as they pass Carlton Rd. Junction, about 3km/5mins from St Pancras whereas from London Bridge to East Croydon, even if the route is clear, no trains seem to carry much speed on that stretch of nearly 20km, (which is about the same as Elstree from STP).
 

158srule

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2 units in passenger service from Monday. One is planned for 769452 which will be first 769/4 in passenger service. 769006 planned to be the other with 769003 and 769008 used for driver training next week (Tuesday - Thursday)
 

158srule

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2P05 0606 Cardiff - Penarth
2R06 0633 Penarth - Rhymney
2P08 0802 Rhymney - Penarth
2R09 0933 Penarth - Rhymney
2p11 1102 Rhymney - Penarth
2R12 1233 Penarth - Rhymney
2P14 1402 Rhymney - Penarth
2R15 1533 Penarth - Rhymney
2F21 1702 Rhymney - Cardiff
 

Buzz68

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2 769’s in passenger service today passing a few mins apart at Llanbradach. Confirmation of numbers would be appreciated.
769006 2P07 0702 Rhymney to Penarth and
769452 2R06 0633 Penarth to Rhymney running 14 late. First 769/4 in passenger service. 22.2.2021
 

Roger B

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Apologies if it's already answered upthread, but what are the differences between the 769/0s and 769/4s - are they both bi-mode, or is one sub-class now diesel only? Any other differences? Many thanks
 

6Gtraincrew

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769452's debut day hasn't gone according to plan. Had issues at Queen Street on 2R06 and has now been replaced by 008.

Apologies if it's already answered upthread, but what are the differences between the 769/0s and 769/4s - are they both bi-mode, or is one sub-class now diesel only? Any other differences? Many thanks
/4's have a declassified 1st class section
 
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