P2 Locomotive Company and related matters

I’d still maintain that it is. More components, more weight, stretchy chains etc. IIRC Bulleid wanted to go rotary but wartime materials restrictions prevented this?

 

That in itself is re-assuring, do any of them have the changes that David Elliott had planned you can run computer simulations, but a working model often will prove a design, and show up any short comings, or problems,

 

I thought they were building/had built a scale model to test the theory, or have I eaten too much Stilton before bedtime? It's certainly something I'd do?

 

Think @Sheff said the model is not done yet to prove the theory, it was certainly seen as a stumbling block when i was at DLW in January.
Theory may be ok, the practicalities of making it robust and reliable are another thing.
Be interested to follow events though.
In reply to Sheff as my post awaits approval, it is not made.

 

You’re thinking of what they said they were going to do (1/3 scale, maybe 3D printed iirc?). If this has happened then they’ve kept it very quiet.

 

Thanks for the confirmation.

 

It was one of the reasons given NOT to fit the block as working on a mechanism is easier out of frames, but first, you need to start!!!

 

I'm not so sure that roller chains stretch as such, but more a case of wear in all the individual pins and bushes.

 

I thought that they were Morse chains?
Pat

 

I’ll Endeavour to find out …

(Sorry, I’ll shut up again )

Tom

 

There is much talk in the bicycle world about "chain stretch". Steel components can't stretch unless you heat them up - and even then they will contract again on cooling. The "stretch" is actually down to elongation of the assembled chain due to wear in the individual components (rollers, pins or bushes).

 

Indeed...when you can bend a bicycle chain sideways extensively... it's time change otherwise you'll alter the the sprocket tooth profile.

 

Members asked for more details of the P2 valve gear. Having provided these, it would be appreciated if issues relevant to said gear were being discussed here

The only common factor beteeen this gear and Mr Bulleid’s is the engineer himself. Apart from having a large hand in the design, iirc he accompanied the loco to the Vitry test plant in France.

So your starter for ten …..

1. Can the new design overcome the scoring of the tapered cams that led to their replacement by a five stage stepped cam?

2. Is the introduction of a long rocking lever for one of the inside valves a potential weakness?

(@osprey - posted from the comfort of my sofa ).

 

Ahhh couch potato time. I'm not a mechanical engineer, being, now what is called a "manufacturing engineer" I was a production engineer in the old days. However I did a lot of studying mechanical engineering... I've books taking up shelf room all relevant to mechanical engineering and have patents for machine designs and processes that are still in use today from 30+ years ago.
I still have a insatiable curiosity for things...the valve gear is one on this P2. I like to have a drawing in front of me... I'm now a coffin dodger so that's just me. I still have access to academia and long time friends who are very talented engineers and mathematicians...we can be boring at times.... probably most of the time. I'd just love to see the layout of this proposed gear, I'm sure my colleagues would too..

 

Be good if they could make some input to the design, if they thought it would make a difference..
The thoughts of David Elliott could be brought into the conversation, maybe offering a way to kick start its design???

 

It will ease design of valve gear if we limit max rpm..
No Blue Peter re-enacting.
What max speed for P2 newbuild?
Big ship diesels to day run with elektro hydraulic exhaust valves.
It is about 1% less efficinent than old fashioned cam driven but makes reversing and environment adjustments piece of cake.
As I understand it Pensylvania was not too impressed with some steam locomotive valves and Franklin then designed an improved version that was tested on a single K4 pacific.
Not sure it was tested much better and that is the version that goes into the new P2.
The diesel exhaust valve system is a much safer bet.

 

My understanding is that there was considerable experience of the Franklin gear on locos in the USA. Is what is being fitted to the P2s any different from what was used in the USA?