Nym
Established Member
Northern aren’t trained to use or maintain it and it makes the Class B (TPWS) systems worse in terms of human factors.
Oh, and the cab is completely different
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Porterbrook Cl.769 'Flex' trains from 319s, initially for Northern
- Thread starter northwichcat
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Oh, and the cab is completely different
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RailUK Forums
An accountant at Porterbrook thought they could milk them for another 10 years or so by making then bi-mode without really understanding one does not simply strap a diesel enging onto 30 year life expired frame and components. The Northern 319s were becoming increasingly unreliable which should have served as warning. It's disappointing as clearly a lot of time and effort has been made to convert but new bi-mode train order to replace these cannot come quick enough.
Bertie the bus
Established Member
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And that accountant deserves a very large bonus + a promotion. Porterbrook are doing very nicely out of the 769 farce. It is Northern's passengers and the tax payer who are getting screwed.
5Q11/12 (at least) cancelled.
rmHawk765
Member
It is a shame when you think about the workers doing this - but ultimately all that effort was kind of worthless, and I think everyone with even the slighest knowledge of the 319s' history foresaw that before they even began.
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How exactly?
That is a good point to be fair - but I don't think it's necessarily for the worse.
The trains are owned by Porterbrook and leased to Northern.I would be surprised if the lease agreement doesn't place any penalty on Porterbrook when they aren't available for service.* Maybe Northern prefer this arrangement where they get 'cash back' when the trains fail to deliver, - it would help their funds.
* Unless there is clear evidence that Northern were not servicing them appropriately.
Pinus contorta
Member
I think its fairly obvious they expect the trains ' fail to deliver' if there's a rescue or thunderbird or whatever contingency sat at Wigan. But it is what it is so you just carry on till the end of the contract ( or the sky falls on your head)
They were only ever a stop gap to allow electric running under the wires where routes included lines that were being incrementally wired. It's unfortunate that their reliability is poor as when running properly, they are cleaner, quieter and ride better than the dreaded class 150s. I remember many predictions here that their acceleration was inadequate to use on services scheduled for Sprinters. Despite having a lower installed power to weight ratio, the electric transmission is more efficient, and provides a better torque curve.
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Both the availability and reliability of the 150s are better than 769s. Clearly the 769s are making money for Porterbrook because they wouldn't bother doing the current round of overhauls. Not so great for the Southport line which will continue to suffer from disruption for another five years.
No rescue or contingency sat at Wigan. Now back in the 70/80's you could just have a choice of 20/25/31/37/40/47/50/56..........from a 'proper' diesel depot that could couple up (and had staff....). Now if there are only 2 769's in use and one fails, the 'fit' one has to be stopped as its either gone to rescue or isn't allowed out on its own.
If (when) there's a failure the usual trick is to cancel a return Southport-Man Ox Rd/Stalybridge whilst its worked out which 4 car DMU -already out as replacement can be split into 2's - problem then is that most of these replacements are already short-formed.
Whilst today looked reasonable, with 5 (booked 6) starting the day, 769431 failed at Wigan early, whilst 769434 has been stopped, picking up diagram later today. Too be fair, though, Network Rail have got in on the act with signalling problems in the area.
Pinus contorta
Member
Sorry my bad. Saw the red livery one parked up when I went past the other day and jumped to conclusions.
Thats 769421, one of the 2 ex-TfW units which has run for 2 days and failed on both occasions. Now sat at Springs Branch with one power pack apparently isolated and being used as a training unit. The other unit 769452 hasn't yet made even a test run. Am advised that all driver links at Man Vic are now being trained on the 769's which does not bode well for the Southport line for the next xx years, let alone the poor sods wherever else they are let loose..........ex-GWR units, Man-Huddersfield stoppers??
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19/8 update:- Train crew woes (as well as the 769's) now affecting these Stalybridge/Man Ox Road-Southport services. Currently down to 2 769's in service, with 1 sat at Southport.
Latest Northern performance statistics give 'North Manchester' group as 27.5% short-forms between 22/6 and 19/7.............
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Still going, though!!
Wyrleybart
Established Member
So they are training all Man Vic links on 769s in the hope that anywhere between five and two units actually survive the day in traffic. Astonishing.
I imagine Porterbrook have their own performance statistics for their own fleet. So I would have thought they would have left the visits to Crewe ETD for pantograph fitment and just put them in traffic as DEMUs like TfW used them. Obviously they would be slower on diesel power, but at least the 769s would present themselves for traffic more frequently with less overall cancellations.
I don't think they have enough fuel range using pure diesel mode to meet the diagrams.
Wyrleybart
Established Member
I suppose that is as good a reason as any, but how many miles did the TfW ones run per diagram ? Admittedly downhill from Rhymney but thery probably wouldn't idle like a conventional DMU would they !!!
Why wouldn't they idle. The hotel and auxiliary load on the diesel prime energy sources would be similar for both types.
Wyrleybart
Established Member
Never been on one but I have heard videos and seen people mention that engine rpm sometimes increases without any movement. I sense this is because the diesel engines are effectively gen sets to replace the 25kV feed to the transformer, rather than provide traction current to the traction motors.
The engines sustain the 750VDC line directly. Assuming that the auxiliaries and hotel loads are fed from that line, (the transformer plays no part in 3rd rail operation), when there's no traction motor demand the engine on tickover would probably provide enough power for them, much as it would on a conventional DMU.
When there's no traction demand, the diesel engine/alternator sets needs to provide enough voltage (not power, as such) to feed the unit's auxiliaries - MA set for battery charging, main compressor, plus saloon heating in winter, at least. This voltage needs to be 400 V at least, to match what would be the minimum in third rail operation.
What the engine speed needs to be to get that voltage I don't know, but it will depend on the excitation characteristics of the alternator. For a given engine speed, the more voltage you want out of the alternator the more excitation current you need; and there will be limits on that.
That's the sort of operation you always get on a diesel-electric unit such as a 22X: even when stationary the engines have to be running 'quite fast' to power all the auxiliary loads - in the case of 22X there's the air con to feed, not something 769s need to worry about....
Nym
Established Member
Except that's not how variable excitation alternators work.
Wyrleybart
Established Member
This could get interesting Paul.
I'll just grab a bucket of popcorn and a long drink !!!
I was kinda hoping you would be here to bring some context to 319s and 769s - even though you have not been professionally involved with those with diesels !! So thanks
Nym
Established Member
You don't need to rev the nuts off your car to charge the battery, and haven't needed to for quite some time now.
Same means, larger scale.
If you'd like to know more, I'd suggest reading a book before trying to sound so confidently and authoritatively wrong.
Leyland Bus
Established Member
I remember at my last job, we had a newish Mercedes minibus, a Sprinter van with a posh body built on it in a way and everytime you fired it up, even from stone cold, it would rev the knackers off straight away by itself. Never found out if it was faulty or not but it made me wince everytime as it couldn't have been doing the engine any good!
When there is no call for traction power, the MA only needs to provide the same or similar levels of power as with a DMU, which also have needs for "battery charging, main compressor, plus saloon heating in winter, at least". So how does a DMU satisfy such demands? They don't need 400V. A coasting or stationary 769 does not need 400V either, the traction control system monitors the MA voltage, and when the driver demands power that demand results in the diesel engine raising it's speed and the MA excitation so that the MA output voltage and current increases, matching the demand in a closed loop control system.
The fact that the DC bus is a nominal 750V in normal 3rd rail service doesn't matter. Assuming the 769s use the 319s traction control, the DC is chopped up to provide the correct current/voltage for demand and speed. This is the equivalent of switching in series resistors to prevent excessive current at low speeds on traditional DC motors with an LV supply.
You might be confusing my reference to MA set (Motor Alternator set) with the main traction alternators as directly powered by the diesel engines.
Northern 769s (and all 319s, though that's largely irrelevant now) retain their Motor Alternator set which takes as its DC input the traction DC supply (from the main transformer via a rectifier in AC mode, or from the conductor rail in DC mode, or from the output of the diesel engine alternators in diesel mode. This has a working range of around 400 V to around 900 V DC, the range of voltages seen in AC or DC mode at least. The MA set's function is mainly charging the unit's battery, just the one large 110 V battery in the auxiliary trailer car (where the MA set is) but also the running current of the 110V battery circuit such as saloon lights, traction control functions and door controls. If the MA set input volts isn't in the range I've said, the MA set will shut down and you're discharging your batteries. Clearly, even if the unit is stabled out of service but with the engine running, the diesel engines and their alternators must be generating enough voltage to keep the MA set running. Also, as I said, the main compressor, plus saloon heating in winter.
Conventional DMUs have mechanically or belt driven compressors on the diesel engine, and a separate heating unit, don't they? So, the engine running speed under given conditions is not directly comparable.
From my experience, 769 engines run at three different speeds. The lowest might be termed 'idle', but it's a very fast idle. It's notable though that in warm weather when they've been working hard, the engine cooling fans make more noise than the engine itself when stopped in stations.