P2 Locomotive Company and related matters

I am not an engineer, but I think there may be some who would take issue with the claim that the Bulleid oil bath was 'sealed'. The cases of cladding fires resulting from oil contamination must tell us something.
Pat

 

I think we all know how well that worked in practice. Yes the are a few examples around today, but they cover relatively few miles now, and woe betide anything goes awry, as access to the gubbins is definitely not a 5 minute job.

By the same token, would you described the wholesale replacement of carburettors by fuel injection as “childish”? Both do the job, but one is inaccurate and requires maintenance whereas the other is ‘fit and forget’ until very high mileages and significantly reduces pollution.

I imagine that like myself, and research and development engineer would take offence at their efforts to improve the reliability and reduce running costs of whatever device is judged to be ‘childish’.

A large percentage of my career involved modernising and automating processes that dated back to the early 1900s. They were exceedingly labour intensive, and competition from cheap labour areas such as Asia and latterly China, was killing us. By some inventive engineering and use of the latest plc control we reduced the manning from 160 to 16 imperatives per shift, and massively improved both the working and local environment. Of course the downside was considerable redundancies, but it was that or shut the factory.

Now going back to steam locomotive design, let us take a slight flight of fancy, and pretend that steam would have continued for another 30 years or more. As with my ageing tech example above the new designs would need to minimise the labour and consumables required for servicing and maintainance.

I believe that Riddles and Coleman had it about right. I’d have nothing between the frames that required access for servicing and all lubrication to be grease or sealed boxes where possible. So roller bearings, rotary gear, mechanical lubrication for the rest. For higher power outputs then the DoG arrangement would be employed, ideally with a roller bearing big end.

First to go would be the entire GWR fleet, apart from the few outside motion Panniers perhaps, along with all the older smaller stuff, as wagon-load freight would disappear as we know, and local passenger would be covered by Std 2 tanks, or we accept DMUs?

Anyway, this is a major departure from the P2 saga ….

 

Language......

 

Eh?

 

Deleted

 

One does wonder at what point do they conclude that Gresley was right, bite the bullet and give up the Lenz gear in favour of Walschaerts? And if you are doing that it probably makes sense to follow Peppercorn and give it as near as possible the same motion as the A1.

 

I suppose you didn't curse... I do with matters like that...

 

Gresley gave up on the Lenz gear for good reason at the time, when the improved derivative that the P2 is intended to have hadn't yet been invented. I don't know much about it but I assume that, like Caprotti, it allows the ports to open fully even at short cut-offs, which Walschaerts, Stephenson, etc, can't do.

 

It isn't going to be Lentz gear. This was not completely satisfactory but showed promise. The development of the Franklin/Lentz type of gear was many years after the first appearance of a locomotive fitted with the original type in 1900. Franklin took on the Lentz patents in 1940 and 40 years is a long time in engineering development and a glance at any field engaged in mechanical engineering in this period illustrates this. PV12 was first flown in 1935 and developed 740 hp and by 1940 was producing in excess of 1,000 hp. In 1900 an aircraft engine might produce 50 hp, by the 1920s it could produce 500 hp or more. True progress in some fields was more rapid than in others but everything moved forwards. Vernon Smith's book One Man's Locomotives can be found new but is now well in excess of £500 but second hand are available from sources for less than £200. So you can find out more with a little research, Franklin Company patents might be rewarding.

 

I don’t think aero engines is a very good comparator. There were a couple of events in 1914-1918 and 1939-1945 that drove technological innovation - the pace of development was slower outside those times. Moreover, the technology was also very young at that point, which you’d expect to lead to rapid development - comparing the pace of engine development up to 1945 is equivalent to looking at steam locomotive development up to 1850, which saw massive change - much slower progression thereafter.

For steam locomotives, there was technical development happening in the inter-war years, but I’d suggest valve gear changes was a very minor part of that. The big developments I’d suggest were:

• A rapid increase in superheater area and temperature, even at the expense of heating area. (Broadly - swapping tubes for flues). That led to much bigger gains in thermal efficiency for locos that spent much of their working duty at high outputs. That change was in turn enabled by developments in lubricating oils.
  
• Development of welding as a mechanism for both construction and repair - including both steel and copper
• Minor, but incremental, improvements designed to increase mileage between overhauls and thereby decrease cost.

In addition of course, there were developments in non-steam traction.

During and post-war, the significant trends were two fold: firstly improved ergonomics, and secondly anything that reduced labour requirements - you can see introduction of hopper ashpans, Bulleid chain driven valve gear and the Ivatt / Riddles reversion to simple, two-cylinder designs as all facets of that trend.

So the summary - development engineering of steam locos continued in the twentieth century, of course, but they were primarily incremental changes looking at various facets of running costs, of which the greatest was manpower. In that light, moving away from Walschaerts valve gear just didn’t seem to lead to much gain for the inevitable development costs and teething troubles it would lead to. The one significant contribution to thermal efficiency in the twentieth century was the rise of superheating.

Tom

 

As a fan of a wry understatement I enjoyed this bit.

 

Fitting Walshaerts gear to the existing P2 monobloc is not a casual thing, almost a start from scratch... if this is even a shadow in the minds of the p2 team then offering up the existing bloc to the frames is a but pointless yes ?
It is childish to suggest any other valve gear offers significant advantages over walshaerts ? , but some undoubtedly do have plusses.
The improvement here isnt just the valve gear per se its the type of valve...which theoretically has always been an ideal solution, getting a valve gear to action it both effectively and reliably has though been many decades in the making

 

For Gresley enthusiasts, a somewhat ironical, consequential development:

Junkers Jumo, Napier Culverin, Napier Deltic

 

The P2 group have committed to the Lentz gear, right? Now that major components are made, you would be insane to switch to something else at this point.

With careful engineering management, the design choice that has been made, will be a success. The rotary valves give more control over valve events, dont they?

Some major advantages in that, I suspect.

From P2 website.

"Lentz poppet valve gear is a more efficient design than Walschaerts valve gear, which is commonly found on UK locomotives including Tornado. Lentz developed the concept by which an improved system of large passages, large areas through valves and suitably controlled valve events, would fully utilise the latent capacity of the boiler. Lentz poppet valve gear was fitted on the first P2, No. 2001 Cock o’ the North, and we will be taking this principle and applying it to the valve gear design for No.2007."

 

The well worn phrase "if in a hole stop digging" springs to mind.
Now it may be that they have all their ducks in a row, all the detailed engineering design is complete and signed off and all that's needed is fabrication and assembly, in which case, sure, they should go ahead.

But times have changed, money is tighter, steam engineering expertise is very hard to find. The A1 was a relatively straightforward and sensible project, based on a highly successful design that only needed to be modified where engineering capability had changed. The P2, by contrast was hugely ambitious, aiming to cure problems with a flawed design that steam age engineers abandoned. It may be worth asking the question "can we complete this within a reasonable timescale with the resources *now* available to us, and would simplifying the design enable us to complete it significantly earlier so more of our contributors are able to see it running before they drop off their perches. And once they've completed it they need to keep it running. If there are problems with the Lenz gear that need sorted that'sgoing to be a big financial drain too.

 

And scrapping the block, designing and making a new one, and all the associated knock on's wont be expensive.....?

Making a dramatic change at this stage would also extend the timeframe to completion.

 

Theres always the 'cant we use the cylinder x 3 design from tornado and rejig it a bit' option... would need to weld up that big hole on the frames, re d0 the crank axle etc but it'll be safe...

 

I don't have the answers, I just think the question might be worth asking.

 

Or just save even more time, admit Thompson was right, and rebuild as an A2/2... (edit: smiley needs very much to go here, but it's not working for some reason)

I think the A1SLT are in a cleft stick. Rebuilding the block (to the extent it is possible) will have innevitable knock-on effects, draughting, rail approval, valve events etc. As would the immensely expensive course of building a new block.

There again, as nobody has made the Baker gear work for it, that's going to be an expensive road too.

 

Ye Gods, folks... let's stick to the original concept and create David Elliott's vision. It's going to be hard as David is no longer with us. It's going to take an exceptional advance forward with the right personnal and foresight... I'm just being selfish... I just want to see it finished before I go to landfill.. it's creeping up on me..