Bullhead rail wooden key dimensions?

[LightBrigade]

Dear assembled wisdom...

 

Regarding the wooden key that wedges the bullhead rail into a sleeper chair. Does anyone have any dimensions for these? The internet via Google is not forthcoming with an answer (except to hint some might be slightly tapered in order to wedge it in).

 

Some months back I acquired an old LSWR chair from eBay which I have painted up, and more recently a suitably short length of rail to put in it from a scrap bin. 

 

Now I'm only missing a lump of wood to hold it all together - how hard could that be? It's not that easy to take meaningful measurements to allow enough give to wedge it all into place, and not be either too loose or not fit at all.

 

If anyone has access to dimensions for me to fettle something, or better yet an old key to measure, I would be eternally grateful!

 

Edited June 26, 2023 by LightBrigade

[Wickham Green too]

I'd hazard a guess that your bit of rail is a heavier section than the chair was designed for - so will required an undersize key !!?!

[Jeremy Cumberland]

Keys varied in size according to the type of rail and chair. Usual modern practice is to use hexagonal section keys, where both sides more or less match the rail profile. Older keys (or perhaps cheaper keys, used in sidings) were rectangular in section, more or less matching the rail web height (never greater than this, obviously). Since you have a piece of rail, you can use this as a template and it's up to you whether you use a hexagonal key or a rectangular key.

 

The width of the key is simply the gap between the chair and the rail, with the rail web firmly up against the chair. Keys are slightly tapered - from memory by about 1 or 2 degrees, which isn't a lot - and the narrow end of a new key should slide easily into the slot between the rail and the chair, but should bind before the key is very far into the chair. Keys are generally a little longer than chairs are wide, and a correctly sized and correctly driven-in key should project on both sides of the chair. Since you have such a short piece of rail, having a correct length key might look a little odd, and I expect that a key the same length as the rail would look best, and driven in so that both ends line up with the rail ends.

 

Keys are made of seasoned hardwood. Oak was traditional, but more recently other woods such as jarrah have been used. At any rate, choose a wood with a close grain - a piece of pine would look very odd, to my eyes at any rate. Since you probably won't want to use a sledgehammer to drive it home, you might need to begin with it being slightly oversize and then very carefully sanding it down till it is a perfect fit. Make sure the wood is quite dry before you start - you don't want it to shrink (it used to be reckoned that rain caused new keys to expand, helping keep the rail firmly in place, but I am not sure that this is true).

 

It isn't clear whether your piece of rail is brand new or has some wear. If it is brand new, it doesn't matter which way round the rail is, but it if is worn, then try to find out which way round it should be. If you don't know whether the LSWR had keys on the inside or the outside, I suggest you assume they were on the outside since this was a lot more common, and have the worn side of the rail head on the side away from the key.

 

I've stuggled to find a good photograph of a hexagonal key in situ, but here is a widely-shared drawing:

[Michael Hodgson]

They used so many, surely they were "mass-produced" and supplied to PW gangs by the bucket load if not wagon load?

Or did they expect the gang to chop down trees and make their own ??

Would a lengthman be expected to carry a supply with him to replace those he found missing without trace?

[rodent279]

Reckon if you look hard enough on an old stretch of railway, or in an old yard, you'll eventually find the genuine article somewhere.

[Jeremy Cumberland]

Keys were produced in large quantities, of course, but they weren't all the same size. Different keys were made for different rails.

 

Lengthmen didn't carry keys on patrol, at least not in my experience. A keying hammer and fishplate spanner are quite enough weight to carry around. If the patrolman noticed a number of keys missing, someone might be dispatched with a bucket of replacements and shims and a keying hammer, but key replacement was more often left for the gang.

 

You might struggle to find a genuine key in good enough condition to use in a display. Wooden keys in good condition tend not to fall out, so the ones you might find lying around are likely to be rotten. A former colleague of mine who sometimes made up display pieces used new keys where they would fit, but would make individual keys by hand when they wouldn't.

[Wickham Green too]

47 minutes ago, Jeremy Cumberland said:

... You might struggle to find a genuine key in good enough condition to use in a display. ...

... but when I collected mine, umpteen years ago, it came from a recently closed railway - near what is now the Battlefield Line if I remember rightly : it's 156mm long x 60mm thick ( tapering to 55mm ) x 85mm tall in the centre / approx 70mm at the edges ....... apologies for the metric dimensions but nothing gives a round figure in Imperial !

[Steamport Southport]

How many do you want?  😜

 

https://www.rail-fastener.com/chairs-and-keys-in-railway.html

 

Most railways switched to metal keys quite early on. I would suggest that wooden ones are pretty rare even in preservation due to modern standards.

 

Any local heritage lines you can get to? I'm pretty sure if you ask the right person they might have some old ones they no longer need. These things are bought in bulk and do get replaced on a regular basis.

 

 

Jason

[Wickham Green too]

16 minutes ago, Steamport Southport said:

How many do you want?  😜 https://www.rail-fastener.com/chairs-and-keys-in-railway.html. ..

Hmmm ..... never seen those JBBH thingies before !

[Peter Kazmierczak]

Approx 6" x 3" x 2" from the example in my garden (in an LMS chair).

[LightBrigade]

Wow, many thanks everyone - I had a fear that this might be sufficiently niche to drop off the front pages without a second glace. Indebted to all of you for the information and suggestions.

 

@Wickham Green too, I'm just young enough to be a metric boy so definitely happy with the dimensions you've posted, thank you ever so much - I think this might well be the starting point in a scrap timber pile for me to work with. And I will definitely need to measure it up and check carefully - I didn't think about the fact that rail salvaged from a scrap bin in 2023 is likely somewhat heavier than the 1884 chair was designed for (though it does slot in and locate quite neatly nonetheless).

 

@Jeremy Cumberland, thank you for many further aspects I hadn't thought about in terms of making a display piece. The rail section looks mostly unused but I'll try it both ways around and see what works best. The rail sits naturally in the chair with space for the key "behind" as seen in my initial photo, so I think that's what nature/the Chief Engineer intended. Meaning my windowsill is now the four-foot... that might mean more safety paperwork!

Edited June 27, 2023 by LightBrigade