Leaders.....

The marmite of late steam designs.

To me they represent a bold brave new idea to save steam - but in his Bulleid way, took too many risks and should have played some parts of the design safer.

For example the complicated power bogies, with all sorts of new oddity ideas going on, to mind comes the oscillating liners in the valve gear.

Another issue was the offset firedoor making it difficult to fire.

My argument goes something like this.....

Had bulleid gone for convetional stephensons/walshearts valve gear on each driving bogie, an all conventional boiler with a modern (Porta) draughting arrangement - could they have been a success? No running round, simple outline, powerful. To me a missed opportunity.

Bullied a great engineer, but didnt know when to play things safe


Sent from my iPhone using Tapatalk

 

I don't think there's any doubt that if Bulleid had changed every aspect of the design from wheels to roof it could have been more successful.

 

Bulleid’s turf burner had conventional piston valves and Bulleid/Walschaerts (chain driven) valve-gear. In testing it was much more successful than the Leader, the principle reasons for not taking it any further were unrelated to any remaining design flaws. But Bulleid had also commenced a major dieselisation programme, ordering a large number of locomotives, and CIE preferred to concentrate on this after his retirement.

 

I refer readers to @Jamessquared Tom's post from some years ago, which I always think of whenever the latest thread on the Leader arises:

 

How very... pedestrian! The problem of coal dust when a Leader Mk2 is in reverse; a massive blind spot directly in front of the front bufferbeam, whilst any improvement in acceleration that total adhesion gives is surely worthwhile. Equally, difficult to get between the frames to access the valve gear on such a compact machine...

Still, wouldn't have changed the fact the 'Leader' was built for the world. It provides a great talking point and 'what if' scenario. Just a shame it wasn't classed as a mixed traffic (rather than 'light' passenger/branch/shunting) locomotive from the outset. If successful, it might have even mopped up duties handled by N15s and S15s.

 

I don’t think there was anything wrong with the wheels - or the roof for that matter. It was the bits in between ...

Tom

 

I suggest a good read of Wardales book on The Red Devil. He managed to rebuild a modern locomotive to be about 15% thermally efficient across the board and without doing anything that radical to it.

He makes wto very good points about the steam locomotive in the book, the first is the impact of its inefficiency, not in terms of the cost of coal but the costs of transporting and handling coal, and the resultant ash, and the failure of its protagonists to build better and more efficient locomotives when the technology existed.

 

Mr Bullied ultimately perfected his design of Leader into a successful working locomotive with nearly twice the tractive effort. They were called 10201, 10202, and 10203.

Tim

 

Who?

 

The Leaders had the basic problem of getting live steam to a moving bogie.
And exhaust back again.
The Heisler supplies torque via 90 degree gearing like a Hymek locomotive.
It is fun (for some) to speculate how fast a Heisler like UK steam locomotive could run reliably if Jarvis had got the job instead of Bulleid.
Two cylinder intermediate steam dryer compound was good according to Chapelon and a 90 degree V2 has very good balance


https://live.staticflickr.com/3196/3153874023_37106f5043_b.jpg

Can someone here supply a link to princip of Hymek?

 

Garrets seems to have solved this one and were common enough





Sent from my iPhone using Tapatalk

 

I didn't know that traction engines had flexible steam joints? Or did you mean Garratt?

Keith

 

Just started reading Kevin Robertson's book on the Leaders, and have to say that at a first cursory glance, it seems that Bulleid had no intention of sticking to the brief given for 25 shunting tanks... One memo reading "25 shunting tanks of unspecified design". So did Bulleid in 1938 simply seize his chance purely to satisfy his no doubt brilliant Engineering mind by using SR funds to finance his planned R&D work? Lovely machines that the MNs & Light Pacifics are, they most certainly weren't mixed traffic locos, just as the Leader wasn't a shunting tank.
To me, the Leader seemed a massive sledgehammer designed to crack a nut - which it failed, miserably, to do.

Richard.

 

All that was needed were LMS 2-6-4 tanks, which the Southern got after nationalisation

 

The Southern had a definite stigma about the use of large suburban tanks after the Sevenoaks disaster of 1927... Which was sad considering that it was the condition of the permanent way which was a major contributing factor to the crash, not excessively bad riding on the River 2-6-4T's part.
The only downside of using 2-6-4Ts for shunting at Waterloo was the weight transfer away from the driving wheels on starting, which could cause problems on steep gradients - This was why Bulleid wanted 100% of the Leader's weight to be adhesive. But the sheer size of the thing was prohibitive for use within the environs of Waterloo - As events panned out, the nearest that 36001 got to Waterloo was Hither Green Depot.

Interestingly, Robertson's book shows diagrams of other proposed ideas which never made it past the drawing board (mercifully), but a double-ended Q1 with air-smoothed cowls was considered... This was apparently dropped because of the difficulty of providing control gear from the rear of the tender. Some of the other multi-cylindered ideas looked particularly hideous, I have to say.

Richard.

 

And the power to weight ratio was, how shall I put it? Well at the time these machines were built 40ihp per ton of of locomotive weight was the established standard for steam. So perhaps flywheel horsepower should be an equivalent. Whichever way you might choose to look at it there is only one answer. And anything positive is not the answer.

 

I'm not really sure about that interpretation. The River tanks weren't built for suburban services; they were designed as a mainline loco, and the problem on the SR with big tank engines was their use on the mainline. In that regard, it is worth remembering that it wasn't just the River tanks on the Kent mainlines that had an issue with instability - the LBSCR L class Baltics had to be modified after the first one was introduced, with a large well tank squeezed in between the frames and the side tanks reduced to very minimal volume - I think they could only be filled to 18" height. The side tanks on those locos were retained for aesthetic purposes; but they contained minimal water.

Meanwhile, for suburban use, tank engines remained in use well after the Sevenoaks disaster, notably large numbers of Wainwright H class, Drummond M7s, Billinton D3s and so on. It was electrification that caused them to move from suburban to more rural duties, not a desire to remove tank engines. (i.e. there was no intermediate phase of using tender engines on suburban duties; the tank engines remained until replaced by electrics).

As for the Leader, I don't think the intention by the late 1940s was primarily for use round London in any case, since in essence those duties didn't exist for loco hauled trains. Rather, the intention was a go anywhere design in the further reaches of the Southern, particularly in the West Country. The April 1946 specification from the Traffic Manager was as follows:

Routes and weights to be hauled:
Plymouth to Tavistock or Okehampton: 256 tons
Okehampton to Halwill Junction and Bude: 256 tons
Banstaple and Ilfracombe: 325 tons
Exeter and Exmouth: 384 tons
Bournemouth and Swanage: 320 tons
Brookwood (or similar stabling grounds) to Waterloo: 450 tons
Speed of trains: 50 - 60 miles per hour
Distance to be run between taking water and coal: 60 miles for water and 120 miles for coal.
​

That usage is primarily in the West Country, with the addition of empty stock trains into Waterloo. There is a subsequent letter (October 1946) from the Traffic Manager to the General Manager outlining the justification for needing to replace the M7s; though interestingly that letter notes that there were still 104 M7s in existence (25% working empty stock trains between Clapham Junction and Waterloo; and the rest on West Country branch and local services); the proposal in that letter was for 85 locos (i.e. the 25 already proposed, plus another 60). So 85 new locos to replace 104 old ones, though the specification makes no mention of what the target availability was supposed to be.

Tom

 

I read Kevin Robertson's book from cover to cover when it first came out. By all accountants the Leader whilst a fantastic concept was actually inherently and fatally floored in design. The crew were split, the firemans working conditions were totally unacceptable and plain dangerous, the sleeve valve concept was unsuitable for use in railway applications, the crank axle was weak by design, the driver at No1 end was boiled due to sitting in front of the smokebox, the dry backed firebox was unsuitable for use in a transport application due to the vibration, it was massively too heavy/wide/high, weight distribution was unacceptable and it used more oil for lubrication than a 1st gen diesel electric did for fuel over the same distance!

Err no, the Leader was a duck that was deceased before it left the drawing board. That said, hindsight is a wonderful thing and progress is not always in the forward direction.

 

In short a number of suitable loco's existed on other railways - LMS 2-6-4's GWR Prairies, etc that Bulleid could have used as a basis for a new loco - but didnt.