Pick-up shoe failure

They do not need to be stronger than they are. Reason: when a shoe runs into obstruction, you want to limit damage to the shoe itself, avoiding damage to the current rail or shoe suspension.

Bit of info, but not much, here:

www.brecknell-willis.co.uk/shoegear_datasheets.htm

They make shoegear for quite a lot of LU Rolling Stock, so they may be happy to provide some info if you were to ask them.

Shoes on the underground are solidly fixed (some automatically retractable, some only manually retractable), and the Standards require that they have a frangible part that is intended to break if a certain force is applied - a shoe gone out of gauge that would not break off could cause hundreds of thousands of pounds worth of damage as it goes down the track.

You have not picked an easy project - do you have to just design something that would/could work, or does it have to be something that would be marketable (comparable life cycle costs to the existing shoegear)?

Don't know where shoe failure is most common. It will almost certainly be a line with a fair bit of surface running, such as Met, District, Picc, Central.

At this point the project could go in a number of directions. It can go "something that could/would work", but it can also be purely theoretical as well.

But thank you for everyone who's helped so far.

Is this the rocker (circled in red)? s992.photobucket.com/albums/af47/triassicranger/?action=view¤t=rocker.jpg

Shoes are often found at trackside having become detached from shoebeams. Many cause no damage at all but a low shoe can be disastrous. At the beginning of the noughties I attended a track failure at the entrance to Ealing Common depot. When I arrived it was quite obvious that the track failure was insignificant compared to the other damage. One of the last trains into the depot from Ealing Common had hooked a 'V' in the current rails while negotiating the points and had pulled the negative rail which lifted off the pots, took up the slack in the snake, pulling section after section of negative rail and snakes uprooting the walkboards to the shunters cabin in the process and eventually the leading bogie derailed about a trains length or so into the depot. It took all night to rerail the train, repair the traction connections, walkway etc and check the signalling which aprat from a blown fuse was otherwise undamaged.

Obviously there are devices to obviate shoe failure such as the wooden ramps on approaches to point equipment and trainstops, ramps to lift shoes over rail crossings, low negative shoe detectors to give some early warning of potential failure etc.


I don't know what the procedures are nowadays but years ago all shoes found at trackside were recorded and returned to the rolling stock depots AFAIR for failure and repair evaluation purposes and presumably for the 'paper trail' that is kept on the vast majority of assets.

In my experience Low shoes are extremely rare, what is much more common is out of gauge conductor rail , especially some of the small negi sections in point work, they seems to have propensity to bounce out of position and start knocking shoes off left right and centre.

So, is the rocker what's circled here in red, or is it the entire upside-down t?: s992.photobucket.com/albums/af47/triassicranger/?action=view¤t=rocker2.jpg

I now have a couple of questions:

1) What are the shoes made out of? Are they forged or cast? And out of what material? Steel or iron?

2) I read on here a month ago that the A stocks were being withdrawn from service due to problems with their shoes, but not for the same reason as the D stocks. Does anyone know what exactly was wrong with them?

If the last question is too sensitive please ignore it.

I believe they had developed cracks.

I would imagine that it was the metal brackets between shoebeam and bogie frame cracking. Shoebeams, being wood, are likely to crack far more frequently.

I'm not an expert on the manufacturing process , but the shoes and rockers look like they're drop forged. The shoebeam brackets look like they're cast. Posi- shoebeams are a hardwood like hardwood sleepers, not sure of the type of wood. Negi shoebeams on D stock are Paxolin , not sure what they are on other stocks.

Not LU, but I notice that the new Desiros etc have plastic shoebeams, whereas the old 4-VEP etc had hardwood.

Teak is definitely available, loads of shops here with freshly made teak furniture from Indonesia. Narra is an alternative to teak , not quite as strong though

Plastic that has been painted in scumble? [/cynic]