Ooops.... Trains in Trouble

[AlistairW]

I have no idea how to drive a train or the conditions of the rail head, although I've heard coolant had leaked on the track. My only question is surely if you're applying that much power and rolling backwards slightly the wheels HAVE to be slipping?

Cheers,
Ali

[Rfairlie]

Andy
I have no idea whatsoever But I can find out

However, the main cause of the wheelslip, is too much power, watch it again, he applies power, the train moves, so he then goes for too much power, then it slips.
Just bad driving.

Actually if you watch and listen closely it starts slipping just before the driver applies more power, unfortunately this is just before he opens up thinking that he still has traction. Fair enough he could have shut off again earlier.

Go on you tube and watch the second video of it actually making a clean getaway. Just listen to how much the engine revs up before the train even moves, it's practically on full power and barely accelerating. I still think people are being unfairly critical of this driver in what was a very difficult situation.

Tim

[phill70]

Fair enough, maybe I am.
But some of the comments on youtube are very valid

There is a clear issue regarding controlling trains when you are not used to the motive power but equally modern driving and traction does not require you to think and concentrate as was the case in the past. There is still skill for certain but its a different one of computer monitoring rather than controlling a loose coupled train in the rain.

A touch of sand and some delicate use of power and straight air brake can normally control wheelspin provided the traction is actually sufficient

just shows how the skill of driving has been lost now, thanks to more effective wheel slip/slide management and computers.
That driver should have backed off the power straight away on the first attempt!

[jbilton]

Hi
Even after the revs have come up, there's over 20 seconds of the actual wheels slipping.
Obviously differences in opinion, but that is quite a long reaction time.

Cheers
Jon

[chriscooper]

The problem is, all the time the wheels are slipping they are damaging the rail and the wheels, this is clear to see from the sparks, and is even worse due to it being such a localised area. I wouldn't be surprised if it didn't leave some bad marks on the railhead, which can cause a break in the furture due to the rapid heating and cooling (the same applies to the tire too). At least being a hydralic the wheel speed is limited by maximum engine RPM (which is governed), electric transmission is far worse in slip conditions as an unloaded series wound motor (as used on DC motored trains) has no upper RPM limit, at least until the point of destruction. Whilst very limited wheel slip actually improves traction (achieved though creep control, found on the 60s and the GMs), once the wheels are spinning freely there is a massive loss of traction.

[phill70]

electric transmission is far worse in slip conditions as an unloaded series wound motor (as used on DC motored trains) has no upper RPM limit, at least until the point of destruction

Slightly wrong, as the traction motor breaker would trip first.

[Easilyconfused]

I have never driven a train (unlike some on these forums).

I do however have considerable experience in materials testing in a destructive test laboratory. We did get asked for a second opinion on a rail breakage that was primarily caused by "rail burn" where an locomotive had slipped rather badly and that had caused changes in the rail's structure that eventually led to premature failure well before the expected life of the rail. Thankfully the failure did not result in a derailment but the loss of the track circuits caused signals to subsequently go to red and delayed a lot of trains.

Looking at the rail section under the electron microscope was quite revealing from an engineering perspective when the sample was compared to an undamaged rail sample. The localised heating had produced brittle cell interfaces that were very susceptible to further damage under normal train loads during low temperatures i.e. frost / snow and higher than normal temperatures i.e. in the "heat-wave". In normal ambient temperatures it was not quite so bad but a hard freeze at -10 C or a high temperature of 30+ C showed a high statistical probability of failure. Destructive testing of the remaining samples revealed a 42 - 45% reduction in tensile strength in the transverse direction i.e. across the width of the rail and 60 - 65% in the depth of the rail i.e. top to bottom.

Our findings agreed with the findings from BR's own investigations (that we had not seen prior to our final report) in that the damage caused by excessive localised heating had affected the structural integrity of the rail section. We made no comment on the cause of the heating since that was not in our remit but on receiving the report from BR it became clear it was a wheelslip event.

That was a very interesting package of testing that made a change from our normal testing load. I think I still have the photos somewhere in a box after I left the labs but I suspect I would get hammered if I uploaded them.

[phill70]

After a bit of hard work getting the answer to the wheelslip problem on Westerns, Hymek's, and Warships, the answer is that, they have no wheelslip light, the only indication of slipping is the speedo.
In this case, as it was only running on the rear power unit, the driver would have no indication in the cab, that it was slipping at all.

With that I am going to leave it there.

[AndyUK]

Glyn,

Thanks for looking into it for us.

Andy L

[andyw823]

After a bit of hard work getting the answer to the wheelslip problem on Westerns, Hymek's, and Warships, the answer is that, they have no wheelslip light, the only indication of slipping is the speedo.
In this case, as it was only running on the rear power unit, the driver would have no indication in the cab, that it was slipping at all.

With that I am going to leave it there.

I know im no train driver but surely after feeling the western moving off and then for it start to slip back with more power added would raise concern?

[ralph0chadkirk]

After a bit of hard work getting the answer to the wheelslip problem on Westerns, Hymek's, and Warships, the answer is that, they have no wheelslip light, the only indication of slipping is the speedo.
In this case, as it was only running on the rear power unit, the driver would have no indication in the cab, that it was slipping at all.

With that I am going to leave it there.

I know im no train driver but surely after feeling the western moving off and then for it start to slip back with more power added would raise concern?

That could mean a number of things though.

[Electricfox]

Rescue!

Or not...

http://www.youtube.com/watch?v=zrz82x3_LkM

[ianmacmillan]

I didn't see a brake test.

[salopiangrowler]

you wouldnt need to if theres a second driver in the 50.

you only need to do a brake test after adding another loco onto the front for Multiple working unless theres more than 2.

And the rails were greasy and wet Mcrats arent the best of engines to cope with heavy loads especially out of bewdley, its surrounded by tree's and tree's shed leaves

[ianmacmillan]

A full brake test is not required but a continuity test is.