Train driver 'freewheels' broken down train 13 MILES to London Euston after a power cut

[driver9000]

A single 185 has three engines, one on each coach. An engine dropping out is a programatic thing, managed by the train and its systems, designed to save both fuel and engine hours as I recall (I believe maintenance is done based on running time). The dropped engine alternates coaches each time to balance out the fuel and wear and is most noticeable when stopped at a station when it shudders back to life. I can't recall an engine doing this when the train is in motion

Not allowed to start engines on the move.

 

[driver9000]

Just to echo others, this is one of the most interesting threads I've read on the forum: especial thanks to the drivers who have contributed. Do you think coasting takes place on TPE from Edale to the Grindleford tunnel? I've just assumed they've turned one 185 engine off, but having read this, perhaps it's both.

EDIT: not sure how many engines a 185 has, though!

Yes costing is done nationwide. 185s are fitted with "Eco mode" which when active will shut an engine down (assuming all 3 are running) at predetermined GPS points to save fuel along with wear and tear on the engine.

 

[SansHache]

There was reference earlier in the thread to a Pendolino coasting all the way from Tring to Euston. I can confirm this has occurred on at least one occasion as referenced in the attached extract from an Alstom presentation. The train arrived on time at Euston having coasted for the final 32 miles of the journey. The gradient profile allowed the train to meet the schedule without applying any Traction power having started from an initial speed of 125mph..
Pendolinos have performed coasting tests on the straight, level section of track between Crewe and Winsford on several occasions to measure their rolling resistance characteristics. Extrapolation of the results showed that a train could coast for 34 miles from an initial speed of 125mph before it rolled to a stand (not that we have any 34 mile lengths of straight, level track to prove this on). Steel wheel on steel rail is an extremely efficient technology, particularly if the train has good aerodynamic characteristics.
Coasting in a fault condition (no Traction) or following loss of overhead supply is a different scenario as the driver no longer has the ability to apply power if the train comes to a stand in the wrong place. In this situation it is preferred to bring the train to a controlled stop at a station or signal if possible.

 

[DynamicSpirit]

Pendolinos have performed coasting tests on the straight, level section of track between Crewe and Winsford on several occasions to measure their rolling resistance characteristics. Extrapolation of the results showed that a train could coast for 34 miles from an initial speed of 125mph before it rolled to a stand (not that we have any 34 mile lengths of straight, level track to prove this on). Steel wheel on steel rail is an extremely efficient technology, particularly if the train has good aerodynamic characteristics.

Just discovered this rather interesting thread, so this is a rather late thread-reactivation

One thing I'm curious about reading this... For electric trains... isn't there a fair bit of friction from the electric pick-ups? Either where the pantograph touches the live wires, or - for 3rd rail - the 3rd rail pick-ups? I'm guessing from this discussion that that doesn't have a significant impact on how far you can coast for?

 

[edwin_m]

The pantograph has a graphite top so has very low friction. Its resistance will be tiny. Third rail shoes could have a bit more friction as they are steel on steel and there are sevreral on every train, although they are greased.

 

[Bletchleyite]

Presumably if the power is out the pan could be dropped, in any case.

 

[Bovverboy]

Crossover said: ↑
A single 185 has three engines, one on each coach. An engine dropping out is a programatic thing, managed by the train and its systems, designed to save both fuel and engine hours as I recall (I believe maintenance is done based on running time). The dropped engine alternates coaches each time to balance out the fuel and wear and is most noticeable when stopped at a station when it shudders back to life. I can't recall an engine doing this when the train is in motion

Not allowed to start engines on the move.

Surely, if a 185 automatically shuts down one of its engines, then it will restart it automatically, too, irrespective of whether the train is in motion or not. No?

 

[hexagon789]

Surely, if a 185 automatically shuts down one of its engines, then it will restart it automatically, too, irrespective of whether the train is in motion or not. No?

Not if it's set-up not to start engines while on the move.

 

[A Challenge]

Not if it's set-up not to start engines while on the move.

Why would it need to be though, what's wrong with starting an engine on the move?

 

[hexagon789]

Why would it need to be though, what's wrong with starting an engine on the move?

Depends on the engine perhaps?

I'm not saying it can't be done, but it was stated above that starting a 185 engine on the move was frowned on.

 

[A Challenge]

I'm not saying it can't be done, but it was stated above that starting a 185 engine on the move was frowned on.

I probably should have quoted a different message, but i was wondering what the problem with starting an engine on the move was.

 

[Surreytraveller]

I probably should have quoted a different message, but i was wondering what the problem with starting an engine on the move was.

Probably means the driver is distracted and not paying attention to the road ahead or the signals

 

[hexagon789]

I probably should have quoted a different message, but i was wondering what the problem with starting an engine on the move was.

No idea.

Probably means the driver is distracted and not paying attention to the road ahead or the signals

But in the context of the evo-driving system which uses 2 put of 3 engines and automatically rotates the one cut-out to even out wear, it would be automatic.

At least that's what I think the original post querying this was pondering.

 

[A Challenge]

At least that's what I think the original post querying this was pondering.

It certainly was what I wondering!

 

[hexagon789]

It certainly was what I wondering!

You and me both. If the driver was to suddenly need at both more power while in eco-mode, why couldn't they simply cut out the eco-drive and have all engines running while still at speed.

 

[LOL The Irony]

You and me both. If the driver was to suddenly need at both more power while in eco-mode, why couldn't they simply cut out the eco-drive and have all engines running while still at speed.

Probably regulations say they can't.

 

[randyrippley]

Why would it need to be though, what's wrong with starting an engine on the move?

I would have thought there would be a risk of blowing the gearbox / torque converter as you'd have a problem matching the engine / driveshaft speeds

 

[hexagon789]

Probably regulations say they can't.

Most probably. I just can't work out how an engine would be affected starting up while the train as at speed against it being stationary. What's different other than the speed of the train?

 

[hexagon789]

I would have thought there would be a risk of blowing the gearbox / torque converter as you'd have a problem matching the engine / driveshaft speeds

It can change-over at speed, so it should be able to pick-up from low revs at speed.

 

[randyrippley]

It can change-over at speed, so it should be able to pick-up from low revs at speed.

Possibly not if you have a multistage hydraulic gearbox..........jumping from one gear to the next is trivial, jumping from neutral straight to "3" (or whatever top ratio is on these) could be disastrous. You'd be trying to overspeed the torque converter and/or gears, depending on how the hydraulics are arranged. One of the reasons you don't tow-start automatic cars

 

[hexagon789]

Possibly not if you have a multistage hydraulic gearbox..........jumping from one gear to the next is trivial, jumping from neutral straight to "3" (or whatever top ratio is on these) could be disastrous. You'd be trying to overspeed the torque converter and/or gears, depending on how the hydraulics are arranged. One of the reasons you don't tow-start automatic cars

But the transmission will cut back in at the appropriate stage for the train speed, every time the driver reapplies power after coasting.

 

[randyrippley]

But the transmission will cut back in at the appropriate stage for the train speed, every time the driver reapplies power after coasting.

my understanding is that when coasting the transmission is still full of fluid, it doesn't disengage

 

[robbeech]

But the transmission will cut back in at the appropriate stage for the train speed, every time the driver reapplies power after coasting.

There would potentially be problems if a driver applied full power and the 3rd engine started and tried to match, but 185s reduce their engine speed to idle when coasting so providing this mode was disengaged during coasting then i see no reason why there would be any issues as stated above.

 

[robbeech]

my understanding is that when coasting the transmission is still full of fluid, it doesn't disengage

They revert to near idle, if they didn't then coasting per se wouldn't really be possible as you'd have a fluid coupled overrun that would slow the train down.

 

[randyrippley]

so.........to engage the third engine to apply extra power, e.g. at the start of a hill climb, you would have to dethrottle the other two engines and coast for a bit while the third engine starts up and matches revs. Anyone see the problem?
Also how much thermal stress would you put on the engine in going straight from cold to full power?

 

[aleggatta]

The pantograph has a graphite top so has very low friction. Its resistance will be tiny. Third rail shoes could have a bit more friction as they are steel on steel and there are sevreral on every train, although they are greased.

Third rail shoes aren't greased, they are purely metal on metal, although I think the specific steel used in the rail is a composite to aid current transmission and so a lubricating effect might have been incorporated into the composite

 

[Crossover]

Probably means the driver is distracted and not paying attention to the road ahead or the signals

Apart from possibly the TMS (Train Management System) I doubt the driver will be aware of an engine dropping in and out - I don't believe the engine noise is that noticeable from a cab

 

[hexagon789]

my understanding is that when coasting the transmission is still full of fluid, it doesn't disengage

It does on Sprinters (the transmission empties of oil), but I don't know about 185s.

 

[DynamicSpirit]

Wow, 24 posts in 8 hours after 15 months of inactivity. Seems I started something... I never realised how productive replying to an old thread could be

Presumably if the power is out the pan could be dropped, in any case.

Would that not cause problems next time you want power, as you now have no power with which to raise it again? Or is there some mechanism to get round that?

 

[37057]

Trouble is when coasting without the power source, you have no compressor to maintain main reservoir or brake supply resorvoirs. Loose that and emergency brakes apply. You also have no battery chargers working and batteries on a 350 aren't the best, so if the output contactors drop out becauase the 'Low Voltage Relay' senses <82v the train will power down. Easily achived when powering the HVAC fresh air fans, lighting, control circuits etc. If this happens at speed this will cause some considerable damage to the wheel treads as the emergency brakes apply but with no WSP either. When the power source becomes available again you have no juice in the batts to power the auxiliary compressor to raise the pan again. Train failed.

And 185 transmissions drain when power is shut off.