Bulleid Pacifics - Past or Present

She's due a retube, so the boiler will go to whoever won the tender, and the bottom end by all accounts needs bugga all doing to it.

 

My guess would be Southall.... But only a guess....

 

Slight tangent, but I Remember reading that one Bulleid WC/BB was selected for rebuild but was later released without rebuild having been deemed too non standard for a rebuild, its place went to another class member.

Does anyone else know of this story, which one and why it was deemed too non standard to be rebuilt ?

 

Would Ropley have the workshop space to undertake the retube? its not a boiler off job after all

 

Have to ask them, I dunno!

 

I think I'd heard she was going to Tyseley for her "heavy intermediate". IIRC, I read that on here in response to speculation that she might go to Crewe, now it's part of LSL. Or maybe I'm confusing her with Bittern?

 

Confusing innit............................

She ends up where she ends up, whether in part or whole!

Can we "assume" that if she goes whole, she goes under her own power?......

 

Well, I'm a bit late on this one, but here goes:

The chain driven valve gear was, in my view, an evolutionary dead end. After all, if you want a low mass valve gear with a self-contained comprehensive lubrication system, then the various rotary cam valve gears have got to be the way to go. Fit a sealed roller bearing big end, as was tried out on a few Royal Scots, sealed needle roller small end, mechanically lubricate the crosshead, and that's nearly all the oiling between the frames eliminated. But that isn't on the rebuild or the original, so we can't do any of that.

Don Ashton, who's a bit of a valve gear specialist, reckons that the outside valve gear on the rebuilt MN is the best implementation of Walschaerts gear he knows of, in terms of quality of events. The inside gear ... is not. The reason for this is partly available space, and partly that it's easier to get good valve events and long travel for outside admission valves (specifically with Walschaerts gear). So make the inside cylinder outside admission as per the original, redesign the conventional gear to suit, and see if that quietens a few of the comments about the rebuilds being 'detuned'.

Given that the inside valve gear will now be behaving the same way as the outside, it may be possible to have no balance weights, so the Light version might be able go to north from Meldon (I'd be interested to see a detailed justification for why the rebuilds needed balancing, I can only assume it was due to the inside/outside admission mix meaning that the valve gears don't get close to cancelling each other out).

The steam reverser on the originals seems to be a bit variable, so although better versions are available, stick with the screw reverse. On the other hand, some crews apparently liked the steam operated firedoors, and it's better for the boiler, so I'm tempted to include those, because you don't have to use them.

As far as I know, the originals were never put through carriage washers, but if you dig out Last of the Giants on youtube you will see a UP Big Boy going through an arch-shaped jet washer, which was apparently routine. Since I prefer the look of the rebuilds, my version will look like a rebuild.

 

Surely what needs balancing, if anything, is the mass of the connecting rods, as those are much more massive than the valve gear and move through a much greater distance. I don't see why the rebuilding would have made any significant difference to those and therefore to the need or otherwise for balancing of the reciprocating component (with consequent hammer blow).

 

Well quite. In theory, with a three cylinder layout the connecting rods get close to cancelling each other out longitudinally (close because the planes and masses aren't the same on a Bulleid), but you still get a moment (J.M. Jarvis calls this the swaying couple) trying to rotate the loco about its vertical axis.

BR knew that the Bulleids coped perfectly well with this, and used a similar the idea on the 9Fs. They couldn't fit in big enough balance weights to balance each side individually (for reciprocating forces), so they had all the balance weights in phase and balanced both sides as one, thus reducing the longitudinal forces but leaving the swaying couple largely unaffected. The 9Fs still had hammer blow from the balancing like any other 2-cylinder loco, but it was the same on both wheels of any given axle.

So given that BR knew that the Bulleid balancing scheme was good enough to use, the only sensible reason I can think of for balancing the rebuilds is the unusual out-of-phase inside valve gear. As I said in my previous post, if somebody can give me the definitive reason (as opposed to just the same level of rampant speculation I indulge in), I'd be glad to know.

Edit to add link, the stuff about the 9F above is just summarising this: http://5at.co.uk/uploads/Articles and papers/The Balancing of the BR Class 9 2.PDF

 

Latest issue of Heritage Railway reports 34046 is going to Crewe for the overhaul and will be out of action for six months.
They also report that her boiler ticket expires on 27th September.........
But she is rostered for the CE from the MHR to the Bluebell on 2nd October?!

 

Been granted a wee stay of execution given how little she's actually done during the time of the current ticket?.......

As for going to Crewe, makes perfect sense now that JH now owns it - no need to put things out to tender anymore!

 

I guess they put in for the ticket extension when the scale of the problems with 70000 became apparent. HR reports that the 70000 work is "now an open ended project with no immediate forecast of timescale".

 

I know that this is a bit of thread drift, BUT it seems that they've opened a can of worms with the Brit - but shouldn't whatever they've found have been dealt with at Crewe when it was there not so long ago under Waterman's ownership?... I only ask as I forget what she was there for!

 

Okay I'm confused now. Just read another article about CE trips which says that 70013 is now replacing 34046 on the 2nd Oct. But when I looked on the Icons of steam site this evening it says 34046 is working the trip.

 

Still shows 34046 on Icons of Steam website as doing the MHR to Bluebell trip.

Edit Green Five beat me to it.

 

Are you saying that the movement of a wheel on an axle, that has only happened recently, should have been detected at Crewe a few years ago?

 

No, because I don't know. I'm just wondering just what Crewe's remit was!

Or is this something that has been manifesting itself since then, and possibly accelerated by events between now and then - ie didn't she suffer some minor collision in the last few years, and is now suffering the affects of "whiplash" a la the Duke has suffered since its own incident?.......

 

LNWR gave Britannia a full overhaul. You seem to be making assumptions about 70000 and 71000 without foundation in both cases.