P2 Locomotive Company and related matters

But 242A1 no one has ever said what the problem with DofG is. Might be nothing to do with the valve gear per se. Br Standard Cylinders/ Pistons and their associated structures and systems ( ie brackets, piston rings, lubrication) have always been their weakest link.
BC Gear is not perfect but then neither is Walshaerts (although second guessing the contents of said document a better realisation of it is available ) Both would be dimensionally unique and therefore one offs . The attractiveness of the BC gear on 71000 and 2007 would probably be the simplicity and accuracy of motion event transfer to the middle cylinder - this can be set and reset in complete syncopation with the outside gear as required by the relative position angle of the Middle cylinder if it can be physically accomodated.

If it cant be made to fit though then there isnt much point in using it. though one wonders how the lentz gear was arranged.
Im not convinced that the improvements available to piston valves would be complimentary across three cylinders via conjugated gear which is a 'compromise' solution. and an independently driven valve gear for the middle cylinder would also be.... challenging.

 

That was because they ended up using stepped rather than continuous scroll cams. I doubt stepped cams will be part of the design for 2007.

 

Not sure which document that is. There was the letter from Porta himself in the early stages of the A1 project, and there's all the stuff from the 5AT project. The problem with most of the improvements proposed there is that they would entail additional development and validation, beyond the considerable amount that will be needed anyway for the P2.

Even if Walschaerts can perhaps be improved, it can't avoid the feature, shared with most valve gears, that earlier cut-off on admission is achieved by reducing the valve travel from whatever it is in full gear, which alters the exhaust timing and reduces the port openings. A longer full gear travel (à la Churchward) alleviates the latter, but Caprotti completely avoids both.

 

I seem to recall that on original, the inside gear was split, with the exhaust valve on one side of the cyl, and the inlet on the other. So, say, the LHS gear operated the LHS inlet & outlet valves, plus the relevant valve on the inside cyl, and vice versa on the RHS.

 

This is what the Lentz gear looks like (as applied to a 'Hunt'):



Foxy

 

Lentz gear as originally fitted suffered from a very high level of cam wear, hence the change to stepped cams offering a limited range of cut-off settings. For any poppet valve installation with the seats in any way affected by expansion of the cylinder block the leakage past the valves was substantial, to try to combat this elastic seats were developed. Another complication. Chapelon took the trouble to measure the leakage and the post Pacific and 4-8-0 designed 242A1, 160A1 and the 141P were piston valve fitted. Porta was also extremely interested in losses due to leakage and he too carried out many tests and measurements. His piston valves leaked far less than poppet valves. In case you imagine that leakage is unimportant, from all sources it can account for 50% of the evaporation. Or, put another way, half the steam you produce does no work, it leaks away past valves, glands, packings, cylinder drain cocks and more.
The A1 Trust have a paper written by LDP geared to the building of an A1. This engine would be far removed from what the trust built. But some of the thinking could be included in the 2-8-2. The external aspect of the design would be little changed. The multi ring piston valves with diffusers would offer the equivalent of an 11"approx. diameter. Multi element piston and valve rod packings would minimise leakage and maximise service life.
When the class 26 was created the comparison of the cylinder performance with that of D of G makes for interesting reading, and the 4-8-4's valves were capable of further refinement and the valve gear was in no way ideally optimised.
If the BC gear cannot be fitted within the existing envelope, what then? Divided drive and a 4-8-2?

 

242A1 - you have a PM.

Cheers,

Sheff.

 

Just got confirmation - founding member no.103, just missed out on the top 100. Good number to have though.

It will be something spectacular given the rumblings they may have hit 200 this week. Frames to be made on the back of this easily, I wonder what else could be done?

What a start to the project. Reading Steam Railway, I was amazed to read what appeared to be the author Peter Grafton writing in with his disapproval of the project. Although he made some salient points I am not as sure as he is that a full "steam ban" will ever come in place on the national network, given the options available to current and future governments with new, high speed rail. We shall certainly see.

 

I always find it intriguing (if at times somewhat irritating too) that the ones who disapprove a certain aim/project, tend to be the ones more vocal, then the ones who support it. Not to mention as so many people have probably already stated in one form or another, enthusiasts have the right to create, follow and support any project or scheme they wish, it is their own right too, and no one really has the right to dictate what they should/could do with their money and support. Don't take me the wrong way, I don't mind people expressing their objections against something, it is their own right to so too, but what I can't stand is these critics stating their objections as though it is a undisputed fact and that everyone should get in line with their own reasoning. Plus another annoying factor is, as I said before, there seems to be critics far more persisitant with their claims of being right and stating them repeatedly, then ones who are in support.

Apologies, just needed to blow some steam...

 

Deeds not words... over 200 Founders on board now. The doubting Thomas brigade can blow as much hot air as they like, clearly there are enough people who believe in this project and the team behind it to put their money where their mouths are - something many of the critics will never do for *any* project....

Foxy

 

Not when I was doing sound recordings of it in the late 1970s. Good engine though.

 

Turn your sound on/up!



Foxy

 

On the contrary, I hastily turned it down very low to avoid being driven up the wall by the horrible racket. I would have turned it to zero, but kept it just audible to avoid missing any real sounds (engine exhaust, speech or whatever) that the sound track might include.

 

Don't forget that magazine editors select which letters to publish and, unlike national broadcasters, have no obligation to reflect a balance of views. So just because one magazine chooses to print a critical letter, doesn't necessarily mean the project's supporters are not equally vocal. It's just they are not so provocative or perhaps not so well-written. That's where an open forum, such as this, is so valuable. All shades of opinion are represented, provided only they feel motivated to post and don't overstep our very wide boundaries of taste and decency. Although there has been a lot of debate here about the pros and cons, strengths and weaknesses of the project, most of the posts have been supportive.

For myself, I think that building a new P2 is a wonderful project. The originals were brilliant but flawed, so there are many questions about how close to keep to the original design and what to do instead, and this, to my mind, makes it a particularly worthy construction project. Hopefully, the resulting P2/4 (or whatever it is called) will be significantly better than the originals.

 

Ok, while looking for something quite different, I found the in-context source of these - if ADB had linked to the original web page rather than the image, it is clear that they are fakes and intended as such!

See http://www.rmweb.co.uk/community/index.php?/gallery/image/39241-60503-a-peppercorn-p2/ and http://www.rmweb.co.uk/community/index.php?/gallery/image/39414-thompsons-great-northern-2-8-2/

The source is Matthew Cousins, in a gallery with a whole load of "photographs" and paintings of hypothetical locos.

Tom

(PS - yes I know, dredging up an ancient thread, but worth acknowledging the source I thought!)

 

Spoke to the "culprit" at a local MRE in November. He has a cracking LNER O Gauge layout.

 

I notice that there has been a small January news update on their website. Workshop being prepared for frames

 

From the update:

Roadshows - a series of roadshows in London, York, Darlington, Edinburgh and Aberdeen will be held in March – May next year. Dates and venues to be confirmed shortly.

No Cardiff?? Interesting.

 

Why Cardiff? Look at the proposed venues - all on the route of the ECML where the P2s ran during their short lives.
More venues may come at a later date.

 

Yes the original P2s ran on the ECML, but my understanding was that the choice of the name 'Prince of Wales' was, at least in part, to help promote publicity and funding.

It just seemed a bit of an omission, that's all.

Dave