Electromagnets to combat leaf fall?

[HLE]

Today's metro had a small snippet on a company who claim that by putting electromagnets close to stations would reduce overshoots by 'dragging the train'....and therefore reduce delays.

Two things I can see wrong with that idea ....surely that increases the risk of stop shorts, and if a train is already in a slide entering a station, surely the magnets would just make matters worse?

Seems to be a pie in the sky idea....but interesting

I would post the link but I can't find it on the metro site. The company was called mole solutions .

 

[davido39]

I don't think it's pie in the sky, it actually sounds like a good idea. Magnets would create extra friction when polarized.

 

[Peter Mugridge]

So this would work like the magnetic track brakes fitted to trams, but the other way round? They're fitted to the track to try to retard the wheels?

 

[Oliver]

Here we are: http://www.molesolutions.co.uk/

 

[ComUtoR]

Don't some units already have magnetic brakes ?

 

[Tim R-T-C]

Wait until they go off by mistake under a passing non-stop train...

 

[bangor-toad]

Looks interesting...

I had seen the RSSB Future Railways competition for this last year and I had wondered who'd progressed.

That it's won through and received some funding for the initial stages means it should be taken seriously. If it works as planned it could have great benefits. Of course, it may still not yet work as hoped for but that's always the risk of new ideas.

Looking at their web pages it seems they're using linear induction motors. These work well and are a known technology. It'll be interesting to see how these translate to rail.

Cheers,
Mr Toad

 

[Ash Bridge]

Surely some serious line side vegetation clearance by NR would be just as effective plus reduce the need for as many RHTTs also?

 

[davido39]

Don't some units already have magnetic brakes ?

I think this is called rheostatic braking, i could be wrong though.

 

[furnessvale]

Surely some serious line side vegetation clearance by NR would be just as effective plus reduce the need for as many RHTTs also?

Attempts to cut back tree growth, virtually all of which has grown since the end of steam in 1968, are fought tooth and nail by NIMBYs and tree huggers, which slows progress in that direction no end.

 

[SPADTrap]

I think this is called rheostatic braking, i could be wrong though.

This is where the electrical energy produced by the motors on braking is dissipated as heat via resistors in the braking system.

 

[gimmea50anyday]

Don't some units already have magnetic brakes ?

The Tyne and Wear metrocars do. Look on the bogies between the wheels you will see what looks like an electrical pickup shoe. Theres one on each side of all 3 bogies between the wheels.

 

[notadriver]

Aren't magnetic brakes meant for emergencies only ?

 

[gimmea50anyday]

Generally yes.

 

[notadriver]

Any train using the emergency brake as a result of low adhesion will incur a delay whether they overshoot or don't.

As an aside why are Tyne and Wear metro cars fitted with magnetic brakes ? Are they driven differently to main line trains in places ?

 

[ComUtoR]

The Tyne and Wear metrocars do. Look on the bogies between the wheels you will see what looks like an electrical pickup shoe. Theres one on each side of all 3 bogies between the wheels.

Cheers.

I distinctly remember watching a video on a safety briefing about a unit that had magnetic brakes and the problems they had with them being too effective and units braking rather hard.

Eddy brakes are already in use in Germany I think too.

 

[455driver]

As an aside why are Tyne and Wear metro cars fitted with magnetic brakes ? Are they driven differently to main line trains in places ?

The magnetic brakes are only used in an emergency, they are rather 'harsh' in their application and so cannot be used as the normal brake.

 

[najaB]

The magnetic brakes are only used in an emergency, they are rather 'harsh' in their application and so cannot be used as the normal brake.

As I understand it, magnetic friction brakes are exactly as you describe, however there are also magnetic eddy brakes which are much less harsh. They are used on some high-speed trains to provide the initial braking, with normal disc brakes taking over as the speed decreases.

The issue with them is that they can heat the track and possibly warp it.

 

[Crossover]

Don't some units already have magnetic brakes ?

Manchester Metrolink trams have "mag brakes" - I have been next to a tram in a station where they have dropped due to an overshoot, but I havent been on a tram where they have activated - I have been told that the brake force of them is quite severe though!

 

[HarleyDavidson]

Management might see the attraction. I don't.

 

[asylumxl]

It's an interesting idea but I don't think it's really workable on a mainline railway with all the variables that would be involved. Let's face it, many people have probably had this idea already and discounted it for various reasons.

Perhaps it could be useful near buffers and help avoid a repeat of the Voyager at Chester. I think It'd be far better to start specifying new orders with Eddy brakes.

 

[DarloRich]

How powerful is the magnet going to have to be stop or slow a ,say, loaded coal/oil train?

 

[hulabaloo]

Let's do away with rails completely and have electro-magnetic levitation trains!

I'm a bit stuck for a name for them though..

 

[142094]

The magnetic track brake on the Tyne and Wear Metro can stop a train from 50 kmh in 100m under good rail conditions, but of course less so during light rain or during autumn. Training for low rail adhesion situations is to brake early and light, then use cadence braking if the wheels slide. The track brake is there to use if needed, and indeed I was on a train this morning which had to use it. Applying the track brakes early enough is often unnoticed by passengers.

Also just to add, if the track conditions are exceptionally bad, even using the magnetic track brake can sometimes not be effective.

 

[HarleyDavidson]

Let's do away with rails completely and have electro-magnetic levitation trains!

I'm a bit stuck for a name for them though..

Try Mag-Lev.

 

[bangor-toad]

Also just to add, if the track conditions are exceptionally bad, even using the magnetic track brake can sometimes not be effective.

From what I can see of this new proposal it overcomes this problem.

The way I think it would work is either
1) that the linear motor is bolted to the sleepers and it would act onto the body of the train.
or
2) the linear motor is on the underside of the train and there are substantial magnetic plates bolted to the sleepers where braking may be needed.

In both cases the rail / wheel interface would have no part in any braking force at all. Electro-magnetic forces can be really quite large and I'll be fascinated to see if this is possible to develop as an utterly independent braking technique - which is what I think the RSSB funding is meant to do.

Cheers,
Mr Toad

 

[furnessvale]

From what I can see of this new proposal it overcomes this problem.

The way I think it would work is either
1) that the linear motor is bolted to the sleepers and it would act onto the body of the train.
or
2) the linear motor is on the underside of the train and there are substantial magnetic plates bolted to the sleepers where braking may be needed.

In both cases the rail / wheel interface would have no part in any braking force at all. Electro-magnetic forces can be really quite large and I'll be fascinated to see if this is possible to develop as an utterly independent braking technique - which is what I think the RSSB funding is meant to do.

Cheers,
Mr Toad

Swap the polarity and you can use the same device to accelerate.

Bingo! No traction motors. (Where's Eric Laithwaite when you need him.)

 

[route:oxford]

Attempts to cut back tree growth, virtually all of which has grown since the end of steam in 1968, are fought tooth and nail by NIMBYs and tree huggers, which slows progress in that direction no end.

This being a recent example in Oxford:-

http://www.oxfordmail.co.uk/news/13789285.Save_our_trees_and_move_this_noise_barrier/

Note the private gate onto the railway from the garden!

 

[Ash Bridge]

Could it be that some of these people are also some of the ones who complain when their train is delayed due to leaves on the line?

 

[PaxVobiscum]

I'm confused by that picture - what is Jean-Luc Picard doing behind someone's garden shed in Oxford? (Along with another man and 3 females)