What Ifs, and Locos that never were.

No doubt the Scots will be affronted to see 36 described in the catalogue as the first 4-6-0 in the UK (rather than England)

 

Also described as *without* outside frames. Shame about the feed pipe to the clack box, looks madly over scale to these eyes

 

How did this work then ?
And what about the Padget loco on the Midland, from memory i belive a six inside cylindered loco , two cyls driving on each axle.
On P2 for the photo of the Kitson loco.

 

Paget's locomotive was a 2-6-2 with four cylinders within each of which were two single-acting pistons. The front and rear axles had two cranks and the middle one had four. Whilst that might sound too much power going through a cranked axle one has to remember that the bore was only 18in and the stroke of each piston only 12in. The entire drive train was balanced and, although I do not know if it was ever measured, hammer blow must have been minimal. Its downfall was metallurgical conflict in the sleeve valves and liners which caused the engine to seize up more than once. A brilliant design that did not receive proper development. I am surprised that the principles were never taken up later by anyone else.

 

I agree, I thought that too when I read about it.

 

I think it was Atkinson who later made successful uniflow road steam wagons of which there was a shunting loco variant.

 

Well, sleeve valves for steam distribution and a "dry side" firebox were also used by Bulleid on the Leader.
Both ideas were practical on stationary equipment, but showed serious problems when subjected to the stress and strain of an operating locomotive.

Cheers, Neil

 

Is there a detailed description of leader? In particular it's sleeve valves? I understand it used oscillating sleeve valves but did he add a mechanism to adjust cut off?

 

My understanding is that it had chain-driven valve gear somewhat similar to a Bulleid Pacific, except arranged with inside admission. The actual reverser gear was steam driven, again analogous to the Bulleid Pacifics (and the Q1).

So the opening and shutting of the steam ports was caused by the valves reciprocating, not oscillating, with the cut off arranged in the normal way.

In addition, the valves had an oscillating motion. That was at the suggestion of Sir Henry Riccardo, and was put in place to help with lubrication and even out the wear. The combined motion was thus reciprocating (to admit steam) and oscillating (to help spread the lubrication); each valve sleeve thus moved in a kind of figure of eight motion.

There is some video of it here:

http://www.liveleak.com/ll_embed?f=47f75e34e489

(Edit: NP doesn't seem to like Liveleak as a video source - this video used to be on Youtube but seems to have gone. The link above should work).

Tom

 

Mesmerising!

 

Best described as a contraption I fear.How was this ever to survive the rigours of running shed life.

PH

 

Well, it was totally enclosed and when you think about it, internal combustion engines can be just as complex within their enclosing body. New developments with loco traction usually take several years to get to a reliable state. Nobody gave those involved the chance to iron out the problems. Probably quite sensibly, I might add. However, I often wonder how a conventional boiler/cab arrangement sat on those bogies would have fared?

 

I think the bogies still needed plenty of attention. The oscillating gear mentioned by Tom was removed during the trials, because it kept breaking the drive lugs off the sleeves, and I don't believe they ever really got to the bottom of the crank axle failures. I don't think sleeve valves were ever going to be a particularly good solution for steam, but it should be noted that the Leader cylinders were considerably bigger than even those of the aircraft engines, and perhaps teething troubles were to be expected. One cylinder for Leader was about half the displacement of a full 18 cylinder Bristol Centaurus radial engine, and had to be double acting as well. Only a small technical leap there... I also can't help but feel that, having produced three classes with excellent boilers, Bulleid rather made a rod for his own back by deciding on the dry back boiler for Leader.

Intriguingly, R.G. Jarvis (of rebuilt Pacific fame) wrote, in a report for Riddles: "The disappointing progress made with the locomotive to date is to a much greater extent attributable to the detail design than to the broad conception.' Opinions on whether various aspects of the design can be considered as detail work or broad concept may vary...

 

Sleeve valve engines required very accurate machining tolerances if they were to work properly and this is one reason why their use in road vehicles tended to be slanted towards "high end" and thus high cost products. Lubrication tended to be a particular problem. The world of the luxury car or of the aero engine (also where sleeve valves were to be found) was about as far removed from a railway running shed as can be imagined.

PH

 

I learnt of the Leader project from my Grandads bookshelf, in Kevin Robertsons "Leader-Steams last chance". A very thorough description of the background, prior experiments and thinking behind leader.

There were two non design issues that contributed to lack of reliability. The first was when the first bogie was built up, it was jacked up and ran on air. Some fool decided it'd be fun to slam it into reverse while running, which lead to the motion getting tangled up. This hammered straight bogie was apparently the one that caused most failures.
The second issue was that the valve gear, designed to be sealed, was ran with the covers off a lot, and so got full of ash and grit.

Presumably what really killed leader was the offset boiler to allow a corridor between front cab and firemans cab. This had to be filled with several tons of scrap to stop the loco leaning over, making it hugely overweight-bear in mind it was intend to replace things like M7s!

 

While by then the GWR & LNER had produced some excellent 2-6-2 tanks & at the same time Ivatt was building his own 2-6-2's more than capable of doing an M7's work but with 'all mod cons'.................

 

This 5" gauge model Leader uses two power bogies based on the motion of a Q1. Whether that would have scaled to full size I know not, but it would have removed many of the parts which caused so much trouble: http://www.bulleidlocos.org.uk/_ldr/ldrKevan1.aspx

 

Really - which ones would they be?

Tom

 

The problem with that line of thought is you start with a flawed concept, and then keep adapting to remove the flaws until you no longer have the original concept - you either layer one bad idea on top of another, each one trying to solve an earlier problem (which is how the Leader evolved) or else you end up back where you started and put in an order for 50 more M7s (or better, quantities of Fairburn and Ivatt tank engines, which is essentially what happened)

Before they settled on the Leader concept, the drawing office considered various designs based on the Q1. The simplest of those was simply to duplicate the driving controls on each side of the cab, such that it could be driven from the left both forwards and reverse. They didn't persist; however, given that the Q1 was essentially sound, going down that path would have given the dual-direction loco they wanted with a minimum of technical risk, and with maximum likelihood that the resulting loco would have been able to do anything demanded of it.

Tom

 

If the idea was for a loco which could be driven without the need for a turntable, why not try a cab at each end? This was done on some Irish narrow gauge 2-4-2 tanks, also on the Wisbech and Upwell tram engines