Smudger105e
Member
The compressor on a 66 is a 2 stage compressor and is driven off the end of the engine so cannot operate with the engine shut down.
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Stop-start 66s
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The compressor on a 66 is a 2 stage compressor and is driven off the end of the engine so cannot operate with the engine shut down.
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edwin_m
Veteran Member
Thanks for that. Presumably it could be changed for an electric one if it was considered worth doing so. Given that the 70s regenerate to charge their batteries, do they have electric compressors to maximise the load that the regeneration could power?
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I understand that diesel (not for road use) is currently about 60p/litre, down from 70p/litre last year, so that's £12,000 saved.
Put it another way, it costs £3,800 to fill the loco up, £650 less than last year.
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Come back Westerns and Warships all is forgiven
ac6000cw
Established Member
As someone else has mentioned, this seems to be basically fitting a 66 with the sort of 'hot start' capability that is fairly commonplace on US locos these days (either as standard equipment on new locos or retrofitted to older ones). So I assume they worked out the pros and cons a long time ago (and yes, maintaining air pressure is one of the important reasons for starting/running the engine).
US railroads obviously think the fuel savings are worth the installation cost etc. (but if you are a big railroad spending billions of dollars per year on diesel fuel, even a small percentage saving translates into a lot of real money).
US railroads obviously think the fuel savings are worth the installation cost etc. (but if you are a big railroad spending billions of dollars per year on diesel fuel, even a small percentage saving translates into a lot of real money).
Jamesb1974
Member
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Why are people quoting stuff about their diesel cars having stop/start capability and "it works fine"?
We aren't talking about cars, we are talking about locomotives. The starting amperage on a class 66 is huge. I can see constant stop/starts negating any fuel saving costs by the need to replace starter motors more frequently.
As for the poster who asked whether the compressor on a 66 could be run off the battery, I very much doubt it. If you leave the tail lights switched on a 'dead' 66, you flatten the batteries in a matter of hours, never mind running a compressor that is required to produce air pressure.
We aren't talking about cars, we are talking about locomotives. The starting amperage on a class 66 is huge. I can see constant stop/starts negating any fuel saving costs by the need to replace starter motors more frequently.
As for the poster who asked whether the compressor on a 66 could be run off the battery, I very much doubt it. If you leave the tail lights switched on a 'dead' 66, you flatten the batteries in a matter of hours, never mind running a compressor that is required to produce air pressure.
It is however reasonable to draw the comparison when discussing the development of diesel technology. The road haulage industry would never tolerate diesels in trucks that didn't start reliably every day. Even more so, one of the earliest diesel applications was in submarines in World War 2, they would operate underwater on batteries in the day to avoid detection, then surface each night and start the diesel to charge the batteries. It would never have been acceptable halfway across the ocean to have the diesel unlikely to start. And that was a couple of generations ago.
Meanwhile the rail industry never caught on to this, it seems, despite the locos costing a fortune. Voyagers running with an engine not operating are apparently an everyday occurrence. There's all sorts of concerns that once a diesel loco shuts down it won't restart easily and consistently. Why not?
All now built down to a price rather than up to a standard!
They have got 3 or 4 other engines so one out is pretty much a non event!
Up to now they have been running almost continually and the only time they are shut down they are allowed to cool (maintenance or stabling overnight etc), trying to start a hot engine takes a lot more effort from the starter motor(s), effort they havent had to make on many occasions before but now they are going to be doing it possibly dozens of times a day!
Smudger105e
Member
You are correct, 66s used on RHTT formations are in multiple, the RHTT has a 27 way through jumper. This arangement saves changing the brake to 'dead loco' on the trailing engine, with the possibilities of driver brake mismanagement.
Smudger105e
Member
or the other possibility is dragging brakes when the loco realises it is moving with the reversers not in for or rev!!
And doing a 67002!
I do hope that a air leak combined with a shut down locomotive won't lead to runaway like this in Ireland http://www.raiu.ie/download/pdf/2012r002_runaway_locomotive_at_portlaoise_loop.pdf
The setup may be different but I hope procedures/systems are in place that it couldn't.
I believe in the eighties Bournemouth depot were once asked by concerned residents why a locomotive was parked in wharfedale road .... after a while depot staff determined that indeed a class 47 was missing ... it was left without a handbrake applied and in the fullness of time had sweetly rolled off down into Wharfedale road. (No one injured, just red faces and a couple of things bent).
The pertinent point here is there something like a handbrake that will auto apply if the engine shuts down and to guard against an air leak, or does the design/procedures make that unnecessary.
I am probably talking rubbish in this regard ... please feel free to call me stupid.
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There's been at least 2 incidents at Waverley. There was a 37 which ran away eastwards down the ECML (downward gradient) and collided with a HST headed towards Waverley. The other one was a 67, I think (only vague memory of it right now), but without a collision, also eastwards on the ECML.
In both cases, I believe the problem was either defective handbrake, or the handbrake not being properly set when left unattended, then air slowly bleeding off. It's a standard and ancient defect of the Westinghouse automatic brake, but procedures should prevent it from being a problem.
Edit: The second case I was thinking of was an EWS 90 off the sleeper, not a 67. It did an unmanned light loco move from Waverley to Craigintinny. http://news.bbc.co.uk/1/hi/scotland/2495429.stm
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O L Leigh
Established Member
Before we get too far down this road, the need to apply sufficient handbrakes to hold the train would not be necessary for stop-start locos, nor the need to hang around waiting for the air pressure to be built. I cannot imagine that a dropping air pressure would not cause an automatic restart in just the way that I and others have already described.
Stabled locos being inadequately secured and wandering off on their own is an entirely different matter.
O L Leigh
Stabled locos being inadequately secured and wandering off on their own is an entirely different matter.
O L Leigh
edwin_m
Veteran Member
As long as the driver stays with the loco to take corrective action if the restart doesn't happen and the pressure keeps falling. Effectively they must treat it as a loco in service not a stabled loco.
Another runaway due to incorrect brake settings was this one:
http://www.raib.gov.uk/latest_news/news_archive/news_archives_2007/070524_pn_east_didsbury.cfm
Yes, you're entirely correct. The 2 cases I mentioned at Waverley are not relevant to auto shutdown on 66s. If they failed to auto-restart on dropping air, they should either be properly secured by parking brakes if unattended, or have someone aboard who can take appropriate action.
O L Leigh
Established Member
Of course. Isn't that what we're talking about? Locos in service waiting in loops and at signals with the driver onboard, not locos shutdown and parked up unattended in the sidings?
O L Leigh
edwin_m
Veteran Member
I agree, but post #23 suggests there could be some confusion on this point. If a stop-start system had been in use at Lac Megantic then the train would still have run away if the loco that was supposed to start had still caught fire and been shut down. Or had failed to start for any other reason.
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O L Leigh
Established Member
Perhaps.
But there are a lot of differences between UK and Canadian operations that would make such an event unlikely. For one thing we don't leave trains unattended on the mainline. But had the engineer set a sufficient number of handbrakes and carried out his brake test correctly the outcome of the engine shutdown would have been that the train stayed put.
O L Leigh
But there are a lot of differences between UK and Canadian operations that would make such an event unlikely. For one thing we don't leave trains unattended on the mainline. But had the engineer set a sufficient number of handbrakes and carried out his brake test correctly the outcome of the engine shutdown would have been that the train stayed put.
O L Leigh
Yeah, I've read most of that report, and the way I interpret it is that the primary cause was insufficient handbrakes set, and insufficient testing of the applied brakes. The mention of the auto start/stop system was only that it might have prevented the runaway, but should not have been a mechanism relied upon to prevent it. For example, if the fire (or something else) had burst the brake lines, it still wouldn't have helped to have a loco running.
The only thing that auto start/stop should have been used for in that case was to eliminate the need to charge the air in the morning, and not for anything to do with keeping the train secured.
Smudger105e
Member
DBS do not trust the parking brake chains on the class 66s and when berthed the loco should also be scotched...
87019Chris
Member
Why has one attempted to run away before or is it just them being very cautious for good reason (as you don't wont a loco out of service).
O L Leigh
Established Member
Forgive me, but can I ask for a source for that?
I know that a few years ago one went for a wander on it's own, went through a set of trap points and ended up in the kitty litter, but if I recall correctly this was because the button for the electrically operated parking brake hadn't been pressed for long enough to allow it to apply correctly. New instructions were issued to drivers concerning this, but I don't recall anything about scotching.
I shall have to have a proper look next time past Alexandra Dock.
O L Leigh
I assume it would be a good thing for safety if the auto shutdown sequence ensured the electrically operated parking brake was applied first.
O L Leigh
Established Member
The loco parking brake alone is unlikely to hold the weight of the attached train on a gradient.
Why are people worrying about this? As already said, we're talking about trains detained in loops and sidings or waiting signals and not left stabled and unattended. These are two different things. Rather like a car with stop-start, I would imagine that the system would not shutdown the engine if there were any indications that it cannot then restart it later. Temperature, battery charge levels and other parameters would be taken into account and, if an auto-restart looks in doubt, it wouldn't shutdown in the first place.
Also there will be a driver present. If the engine shuts down and then fails to restart automatically when it should the driver is on-hand to either manually restart the engine as normal to recharge the air or apply sufficient handbrakes to hold the train on whatever gradient it happens to be standing on.
O L Leigh
Why are people worrying about this? As already said, we're talking about trains detained in loops and sidings or waiting signals and not left stabled and unattended. These are two different things. Rather like a car with stop-start, I would imagine that the system would not shutdown the engine if there were any indications that it cannot then restart it later. Temperature, battery charge levels and other parameters would be taken into account and, if an auto-restart looks in doubt, it wouldn't shutdown in the first place.
Also there will be a driver present. If the engine shuts down and then fails to restart automatically when it should the driver is on-hand to either manually restart the engine as normal to recharge the air or apply sufficient handbrakes to hold the train on whatever gradient it happens to be standing on.
O L Leigh
Jamesb1974
Member
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- 596
I think you might be referring to the original class 66 parking brake chains. One did snap a few years ago, leading to a runaway. Since then, all DBS 66's have a modified parking brake chain (a big, heavy duty thing) fitted.
As far as I know, scotching stabled locos is a local instruction.
In the normal situation you mention this is not a problem. The concerned situation is where a 'normal' delay turns into some different, perhaps into something much longer. A situation might occur say once per 500 loco's so equipped per ten years; perhaps an unexpected event has caused the driver to leave the cab for example; perhaps procedures have not been rigorously followed for some reason.
Also made the comment as because the parking break is electrically operated there would possibly an opportunity for designers of the stop/start to ensure it is automatically applied as part of the procedure; if it was a wheel to be turned manually as in older locomotives then the opportunity for automation would be less.
I do totally respect your opinion however and I am often known to talk rubbish about what I know little; occasionally I raise a valid point.
So following on from my earlier post - and thanks for those who took the time out to reply - just how difficult is it going to be to retrofit these for stop start?
And how long do they expect them to be 'cold' for?
I remember when WSMR started we got grief from those round marylebone because of the engines being idle(though they shouldve been at work) so it was just a shut down they had to do.
And how long do they expect them to be 'cold' for?
I remember when WSMR started we got grief from those round marylebone because of the engines being idle(though they shouldve been at work) so it was just a shut down they had to do.
Smudger105e
Member
I was a directive when I was a depot driver and shunter for them. All DBS 66s have scotches on board for this purpose, normally in the rad corridor causing a tripping hazard!
The cause of the runaway was the driver pressed the PB ON button, the motor started to apply the brake, but the driver knocked the BIS out before the process was complete. DBS parking brakes now carry on running to complete the cycle even if the BIS has been opened.
What has happened historically is that the parking brake chains have snapped. Despite mods (3 yearly chain renewal, link chains replace with a bike chain arrangement) there is still not sufficient trust in them to allow vehicles to be berthed without scotches. That was certainly the case when I left their employ earlier this year.
gage75
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I belive the reason it was that the usage could be better controlled in isolation (i.e. 1 Depot)as it were, this would be easier to do rather than trying to follow it on longer over multiple depots across the country as this in itself would mean training more staff in the various sites and so would increase errors in recording the details required
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