Practical Issues in Preserving Steam Locomotives

Well, If I were going to evaluate the relative success of a class I'd want to know four things:
Could it do the work required?
What was the capital cost of building it?
What was the total cost of ownership per mile (including all repairs)?
What was the availability?
A great class would be equal or superior to all its contemporaries in all 4. Obviously its fairly easy to deliver any one if you are less concerned about the others. Truth is though, I'm not even sure to what extent that data is available in directly comparable figures. I certainly don't have it.

 

I would also add, to what extent did it represent or embody largely successful innovative technology, and how did it transform the operation of the lines it worked and thus the lives of the people who rode behind them?

No Bulleid Pacific is ever going to beat a BR Standard on the bottom line... but I dare to suggest that the great railway pioneers of old would find more to admire in the Bulleids. That, and they ride a lot smoother than Britannias and don't spin their centre driving wheels on their axle (the only trouble in that department being the Crewkerne incident, never repeated)...

 

Just to correct one statement, BB: frame replacement constituted a repair, not a rebuild. Many Black Fives did receive replacement frames as part of their maintenance, while Bulleids didn't. But the Bulleids received a lot of constant repair work in traffic which the Fives didn't need.

The Bulleids needed this constant repair to components which were often almost inaccessible. Whatever footplate crews thought of them, fitters didn't regard them fondly, which is why the attempt to foist them on to the GE section was doomed to failure: they went for Britannias instead.

 

Not quite true about the factor of adhesion - as built (280psi) the figure for a WC/BB is still greater than for a Schools class; and once the pressure was reduced to 250psi, the figure was fairly ordinary - greater than, for example, an A4.

(Greater in the sense ratio of adhesion to TE, i.e. bigger number = more grip, all else being equal).

Of course, a Schools has no trailing truck on which to transfer weight on starting, which helps. All sorts of other factors help or hinder starting which is why I think focusing on one factor or one loco type is wrong: regulator response, steam chest volume, even the typical starting points (getting a heavy train away out of London Bridge is a different proposition to some other termini, for the sample).

There was a thread on wheelslip here, which apart from anything else had comparative figures from @Steve for a number of currently-preserved locos, especially those that do, or have, worked on the NYMR.

https://www.national-preservation.com/threads/bulleid-wheelslip-question.543086/

Tom

 

Indeed, HAV Bulleid makes the point that when the Pacifics started to come on stream, the footplate crew generally loved them, because they did what any engineman wants: pulled anything you could throw at them with plenty of steam available. Senior shed staff had a diametrically opposite view, as the main desire for shed staff is to get the locos off shed when needed, and the Bulleids had low availability. (I suspect lowly shed fitters probably just accepted the overtime payments with a wry smile!)

Tom

 

I rather suspect all this belongs on the long-running Bulleid thread, however!

Is it just me or are we, as steam enthusiasts, chronically incapable of sticking to the point without drifting off at a tangent?

 

Drifting is fine. it is what you are supposed to do with a piston valve loco to help reduce maintenance so it is on topic!

 

Steve, what exactly is 'drifting'? I'd always assumed it was a nonspecific unscientific term for a loco that had shut off steam and was being carried purely by momentum.

 

On a piston valve loco, you leave a little bit of steam on when coasting to stop the valves and pistons pulling a vacuum - this is known as drifting.

 

Err no - that is the purpose of snifting valves. Drifting is simply moving without using steam.

 

So when do you get the back end hanging out? Ala Top Gear.
oops off topic again.

 

No, drifting is coasting with a breath of steam on. As regards snifting valves, it depends where they are fitted. Most are on the steam side, either at the steam chest or in the superheater circuit (LNER). It does prevent a vacuum from being created initially but there is a point where the piston valve closes to admission and a vacuum will then be created which will draw in exhaust gases when the point of release is reached. Drifting steam avoids this and also helps with the lubrication and provides a cushioning effect on the reciprocating masses.

 

Well were anyone unwise enough to build a Dean 3521 0-4-2 tank in its original form it would most likely be able to demonstrate that...

 

A further point with regard to drifting is the provision of a 'D' position on the reverser of Stanier locos. This indicates the recommended position for setting the reverser when drifting. About 45%. BR, in its instructions on the standard locos, simply referred to coasting and not drifting but said that you should coast with a breath of steam on. It didn't specify a cut off other than to say no longer than 40% and 20-25% was perfectly acceptable.

 

That gives me an opportunity to link to this excellent piece by Bert Hooker, describing a run on an unfitted coal train with a Urie Arthur. Although he doesn't specifically describe the breath of steam, he does notch up as short as 20% when drifting, commenting that he considered drivers putting piston valve engines into full gear "completely insensitive to their engine." That particular practice used to have rather catastrophic results on long-travel N7s, which were prone to bending their valve spindles if put in full gear at speed, as the GE drivers were accustomed to doing.

There's lots of good stuff on running a loose coupled coal train in the piece too; that wasn't Bert Hooker's normal business at the time and he makes no bones about his relief at getting an Arthur with a big bogie tender, instead of the usual H16 heavy tank engine, particularly with respect to stopping the train.

 

Why so? I've found few photos of it, no idea what's original or what makes it so bad.

 

And also helps keep Cylinders Hot.

 

As enthusiasts, we look at locomotives from quite a different standpoint to those who ran them on the railways in their service lives.
For us, the locos exist purely for pleasure. Yes, we might get our hands (very) dirty and need them to do a job hauling trains - but even that we are doing voluntarily, for our own personal enjoyment, and the passengers are just having a fun day out.
So little surprise that the aesthetics, the noise they can make, the top trumps statistics on power or steaming rates - these are what wows us.
When engines had to earn their living in more mundane circumstances, you can be sure that accessibility for maintenance, economy, availability, suitability for the job, lightness on the track, etc., were all much more important.
If I may use a slightly mischievous allusion, there is a sort of person you might have a crush on, but know all too well would be a big mistake to marry - and the sort of person you would be happily married to for decades. The personal qualities you might look for in a crush or a fling are not quite the same as those you might look for in a spouse...!

(Whether this has anything relevant to say about certain pacific locomotives from the southern parts of the country I really couldn't say. But you can be sure that cash-strapped parsimonious BR, in the process of moving away from steam, wouldn't have parted with huge sums of cash to embark on a rebuilding programme without some pretty hard realities...)

 

I rode on the footplate of a NG16 garratt in South Africa this year. There was a pull out lever on the right of the cab. I asked the driver what it was and he replied that it opened the drift valve. The regulator was shut and the drift valve opened. I understand that this supplied unsuperheated steam. He also said it could be used for shunting. This was the first time I had heard of this fitting. Was it common on garratts?