71000 Matters

Surely not? You just allow for the relevant mechanical advantage: for example, if you have a 2:1 gear that means you need twice as many piston strokes as normal per wheel revolution, then the TE is doubled (but the same number of piston strokes per minute means the speed is halved, so the power remains the same).

Try working out the TE on this piece of Victoriana ...

https://flic.kr/p/ehn9Sk

Tom

 

Spoilsport! And where rack gear can be disengaged? ....

Unfortunately, the link you provided comes back dead, though there have been some remarkable creations over the years which defy accurate classification, never mind a meaningful, yet always theoretical, TE calculation which in any case takes no account of real-world performance limiting factors from grate area to pinch-points in the steam circuit. For just one example, Lawson Billinton's semi-successful B4X demonstrated this rather too well.

 

Try this for this afternoon's homework



Fell locomotive H199 by Tom James, on Flickr

 

Ooh...... Nice.! That's one o'them Middle Earth Govt Railway locos for the Rikki-Tikki-Tavi line innit?

 

Easy compared with this one¬!
https://en.wikipedia.org/wiki/Steam_Horse_locomotive

 

Does it work with a Shay as well?

 

If you know the gear ratio, yes.

 

..... assuming the relevant components remained what was said on the box, back when they were delivered. A lot of Shays worked for yonks in some very out of the way places (even by American standards) where the remoteness of Lima's production plant made the IMR's Douglas workshops seem just a stone's throw from Gorton by comparison and therefore tended to be even more self-reliant and creative, to judge by the very few photos I've come across.

 

Anyone likely to write anything else about 71000??

 

I'm wondering if the problem with 71000 having "dropped a beat" just before its withdrawal has been identified. I seem to remember at the time that the locomotive had been examined, and that nothing untoward had been found within the camboxes...

Richard.

 

Hmmm, nevertheless iirc some of the modifications to the valve gear made whilst in preservation are being reversed and components are to be replaced to the original 'BR' specification.

 

When they stripped things down they found that one valve had stuck. If all had been well with the finances it could have been put right fairly quickly.

 

I think these are all comparatively minor tweaks, to try to improve performance slightly further or for practical reasons. The major changes from as-built condition in the first restoration were providing big enough holes in the ashpan to let enough air in and in the draughting, and those are certainly not going to be reversed.

 

A bit of tweaking here and there is hardly surprising, after all 71000 was/is a prototype. Should anyone be rich/bonkers enough to build 71001 it'd be interesting to see what design changes were adopted in the light of experience. Possible answers may vary, according to how well the P2's 'breathed on' Lentz arrangement works out, among other innovations since 'The Duke' was built.

 

Not sure the Lentz would work on 71000 for similar reasons that BR Caprotti would not work for the P2. The systems are very similar and I would expect any step forward to be in reliability rather than performance. A new build would Im sure be tempted to use three sets Walshaerts ( which has come on a bit since then) as less difficult/ less expensive, and dukeII would still be a serious machine. Makes you appreciate how brave the restorers were/ the P2 people are for going with this 'on the edge' tech.

 

I couldn't imagine you'd be talking about a 'straight swap' for a moment, though I'd be interested to know why no such redesign might be possible. Using three sets of Walschaerts is precisely the sort of regressive step I would not consider a 'USP' in any putative newbuild 71xxx. As attractive to many as Walschaerts gear undoubtedly is, what exactly would it prove? If that's the notion, one might as well just knock out* another 'Britannia' or, if that's not sufficiently 'P', an Ivatt flavoured 'Coronation' or Stanier 'Turbomotive' (though with a more convincing reversing turbine than the original!).

*term used with all due apologies to those highly skilled and dedicated designers and builders of steam locos!

 

I'd probably rather see a recreation of one of the last batch of the Caprotti Black 5s with a few tweaks to get the best out of the arrangement.

Chris

 

if only they weren't so ugly

 

No objections from this direction (rather like the reasoning too) ..... from what I've seen on other threads, I was beginning to get the impression that nowt under 8P is considered of any use round these parts, but as this is 71000's thread....

 

I rather like them.......