P2 Locomotive Company and related matters

Here’s the latest from the P2 Facebook page ….

 

This has been shrouded in mystery over the last couple of years. I understood that most (90%+) of the design work was completed by the late David Elliott over 2 years ago. David produced a 3D printed model of the valve gear that I've held in my hands. Since then the Trust has, at different times, mentioned the valve gear but it is very unclear whether anything has actually been done. During visits to Hopetown I have always found the volunteers very pleasant and helpful, but they seem to know very little about what is actually happening (or not) on the engineering side. For example, no-one seems to know the current status of the new pony truck cannon box. Has it been cast? Is it waiting to be machined?

 

Last I heard, Riley's had been contracted to fit the monobloc to the frames. I wonder if wooden templates will provide the degree of precision they need to judge whether it will fit.

 

You assume correctly. Apart from being rotary dtiven gears there is next to zero commonality in the layout. Once you have cast the cylinder block then the die too is cast.
Anyway it’s a moot point, what those of us who are paying the bills want is a refined version of 2001, as built. Lentz engineered properly is actually a simpler gear than Caprotti and ought, therefore, to be more reliable.

 

Yes, me too.

 

IIRC correctly getting individual Cam boxes ( as per BR caprotti) on top of the cylinders, especially the middle one was very problematic...

 

To my mind, the fact that the new cylinders have been not only drawn, but actually manufactured, suggests that the valve gear must be very substantially designed. It's possible that there might be some minor outstanding issues, but the substantive form must already have been agreed, because otherwise you couldn't have finalised the drawings and machining of the cylinder.

Tom

 

I don’t understand what all this debate about valve gear is about. It’s like we’ve gone back to pre-2014 times, before the project was launched.

The design has, from the outset, been to build a P2 as per SNG’s original design, but with the flaws (that led to the cams being stepped) removed by the employment of modern design techniques and materials.

If people want something else, feel free to get behind the Doncaster P2 (goodness knows they need it) as they haven’t cast their cylinders yet, though their mission is to recreate 2001 as rebuilt, with Walscharts and an A4 style front.

 

For anyone who wants a primer on the Franklin gear, the paper given to the ILocoE in 1943 is a good starting point, although written by someone who was trying to sell it, so not unbiased.

 

Hear! Hear!

(They're here, if anyone wishes to help them.)