Discussion in 'Steam Traction' started by Kinghambranch, May 24, 2008.
June Update: http://www.82045.org.uk/news/82045_news-jun22.html
July Chairmans Chat http://www.82045.org.uk/news/82045_news-jly22-chairmanschat.html
PLUS July update. http://www.82045.org.uk/news/82045_news-jly22.html
August Update. http://www.82045.org.uk/news/82045_news-aug22.html
The July update included the following:
"The lifting arms on the ends of the reversing shaft have been fitted. These are an interference fit with a key incorporated and the process involved lowering the ends of the shaft into a drum of liquid nitrogen to lower the temperature whilst the boss of the arms were heated to increase the size of the bore. The frozen ends of the shaft were then quickly lowered into the hot bore of the boss of the arms and the temperatures allowed time to normalise. Some calculations had been done in the days beforehand and in heating the boss of the arms the temperature was checked with a heat gun and the bore with pre-set calipers until it was declared satisfactory to lower the frozen end of the shaft into the arm. The operation was filmed and will no doubt appear in due course."
The video is now on YouTube.
Thanks for that, interesting to see. One wonders how they did that in the 19th century when liquid N2 wasn't the industrial commodity it is now; presumably heating just one side and a bloody big press? (rather than simultaneous heating and cooling and a nice sliding fit).
(Fun fact: back in my lab days, a favourite demo for prospective students on open days was to blow up a rubber glove, freeze it in liquid nitrogen and then smash it with a hammer. Having shown the effect of the stuff on organic materials, you'd then take a bit in a cup and poor it into the palm of your hand, which was perfectly safe provided you knew what you were doing - basically keep it moving, and the evaporating gas prevented the cold liquid actually coming into contact with your skin, so you got a drop of liquid floating on a cushion of gas and no frostbite. Don't try this at home kids, we were trained professionals ...)
You lads don't look a day older than when you first became involved with 82045 and still display to all your undoubted skills. Well done all.
What is the rationale for having a circular shaft fitting into a circular hole rather than for instance square? And, given the circular shape, why have both an interference fit and a key? I realise this is "how it's done" but there ought to be an easier way.
Easier/cheaper to machine a round shaft and bore a round hole than machine a square hole and square shaft.
I would think the pin is simply a backup.
I've seen old clips of tyres being fitted to drivers at both Crewe and Swindon and even on old B&W film, the phrase which came to mind was "bloody terrifying"! Effectively, they created their own mini volcano as a trip hazard (and then some) on the shop floor, in which to heat things to about the same temperature differential achieved by the extremes of liquid nitrogen and the torch. Those guys must've been complete experts with chain and gantry systems, as express loco drivers were deftly and rapidly moved to precisely where they were needed.
There was a big deal made at Crewe in the 1930s of electrical heating elements being introduced .... a lot of very big ones (would that have been a Stanier innovation?). I'd have to reckon that sweating like glassblower's ar*e had nothing on working under those conditions.
Really enjoyed that clip. Now the 2nd time I've seen the cryo technique in use (the first was part of Welsh Pony's restoration, already a few years back now).
Also, this shaft has to run on some sort of bearing, so it needs to be round for that too.
The key is there to ensure alignment, but also, as you saw, to ensure that the parts get fitted together in line.
This is nice work, methodical, checking the temps, and great to see PPE too, no chances being taken with safety.
The temperature delta method is so good because its virtually damage free. Pressing a shaft through its interference is always going to lead to scoring, and in the worst case, misalignment.
Will this loco ever go on tour? I would love to see it operate in Strathspey.
I'd imagine there will be a pretty long queue for visits.
Similarly, it would be an ideal locomotive if the Keith & Dufftown ever went into steam seriously. Now the the 3MT in its 2-6-0 form...
When I worked at BREL York.
One of the jobs I covered on relief was Retyring of wheelsets.
In our case the Gas Burners were in a shallow broad pit and could be kicked around to suit different tyre diameters.
Stepping onto the heated tyre was expected as part of the job and the only additional safety gear was issued for this.
Toetector Clogs with mini horseshoes nailed onto the underside. Still got my pair not used since then and lethal for skidding.
I'm hoping it visits Swanage as they used to work there. Briefly...
Ditto the NYMR!
East Lancs? Four did, briefly, end up at Patricroft, which isn't that far away!
Yes, I know it's not going mainline any time soon .... but I'd dearly love to see it on another of the class's former stamping grounds, the Cambrian Coast. A chap can dream!
In some ways not wearing gloves is better than wearing unsuitable gloves when using liquid nitrogen, as it won't get trapped between the glove and skin. Of course, proper cryogenic gloves are best but they are often quite cumbersome to use.
As part of my job, I have to do a Liquid Nitrogen fill once a week - Pressure dewars and onion dewars. The cryogenic gloves we have are leather, but sometimes the frost from handling the connections can soak into the fingers of the gloves. Not very comfortable, but certainly not -196 degrees... Filling onion dewars is the worst part, as the evolved gas forms a dense cloud, which on calm days hangs around and is very slow to disperse. When an onion dewar is full, there's a nice fountain of Liquid Nitrogen until the manifold valve is screwed shut. Had many splashes on the top of my head, it boils off straight away and isn't a problem. We now have hard hats for this, and also Face visors, as well as Lab coats and ear defenders.
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