Bluebell Motive Power

Update on the overhaul of P class 27 - this is I think the same text as was in the last e-Newsletter, but with added photos for illustration:

http://www.bluebell-railway.co.uk/bluebell/loco_news/oh_27.html

Also, the Q made a light engine trip up to HK and back.

Tom

 

In appearance it is very much like a Fowler 4F (a considerably older design) apart from the cab and what I assume to be a steam reverser. How different is it internally? Could the Southern have saved themselves some bother by buying a few from the LMS? (According to my spotter's book there were only 20 Qs, but hundreds of 4Fs.)

(Ready to run and hide if necessary!)

 

I've always thought the same thing... If it had straight sided firebox it'd look completely Midland to me!


Sent from my iPhone using Tapatalk

 

James Clayton, who was Maunsell's second-in-command on both the SECR and SR, and chief draughtsman, was ex-Midland Railway, which explains the somewhat Midlandish outline in details such as the cab shape, tender shape etc of many Maunsell designs. Underneath, however, they were rather more sophisticated, since Maunsell bought Churchward practice in valve gear layout etc! The device on the left hand running plate is indeed a steam reverser. It is the same Eastleigh design as that on a Bulleid Pacific, so it will be interesting to see how it compares with the Ashford design on all the Chatham engines, which is excellent.

I think as well that, the major companies were forbidden from making engines for each other, so even if it had been desirable, the SR couldn't have bought LMS designed locos. I suspect that if Maunsell had survived, there might have been more Q's, but Bulleid found them somewhat pedestrian for their time, and did a total redesign to produce the Q1, of which there were another 40.

Tom

 

i dont know about the LMS 4Fs, but the Maunsell Q class is rather unusual in having stephensons gear with loco links and rocker arms driving outside admission piston valves.

at the time the Q was designed James Clayton was quite ill, and Maunsell wasnt too well either. the outside admission piston valve arrangement required a new cylinder block design, which is rather odd when one considers the SR's lack of money to spend on steam locos during the Maunsell era, and Maunsell's policy of standardisation. if anyone can shed anymore light on why this occurred i would be very interested. (there is a story about Eric Forge at Eastleigh which i dont believe!)

the Q chassis design (including the cylinder block with outside admission piston valves and the valve gear) was later used by Bulleid for his Q1.

i always thought the Qs had the Ashford type of steam reverser.

cheers,
julian

 

There were 4 f built for the Somerset and Dorset or was the ruling on post 1923

 

I think the S&DJR was a special case, in that it was essentially a shell company that was operated by a committee comprising the LSWR / SR (who looked after the infrastructure) and the MR / LMS (who looked after the rolling stock).

I seem to recall the issue about railway companies not providing motive power for each other came after the LNWR started providing engines for the L&Y, but I might be wrong.

Tom

 

as a bit of an aside to Tom's earlier post, their isnt anything 'GWR' or 'Churchward' about the valve gear on the Q!

the arrangement of stephensons gear used on the Maunsell Q (and copied on the Bullied Q1) is most unusual with a large suspension offset on the loco type expansion links - a potentially awkward and un-orthodox arrangement due to the indirect drive (rocker arms) and outside admission piston valves. a far better arrangement would have been to use launch links, with far less suspension offset and die block slip, and also less throw on the valve gear eccentrics. this suggests some non Pearson and Holcroft thinking in the Q design, valve gear expert Holcroft being otherwise engaged on other work at the time.

why Maunsell would sanction a new design of non standard cylinder block with outside admission piston valves and an unorthodox valve gear arrangement for a relatively small class of freight locos has remained a mystery to many for some years! the L1 cylinder block and valve gear could have been adopted instead using existing patterns and many standard parts!

cheers,
julian

 

I was simply meaning learning the lessons of long valve travel, not anything specific about the details of the arrangement.

It is an interesting question about why Maunsell chose to build the Q class, rather than, say, an additional batch of N class moguls that would probably have covered the same duties easily and should not have been significantly more expensive in capital.

Tom

 

I think he might have though that a design over 20 years old was due for replacement.

 

I'm not so sure - Maunsell was above all a pragmatist, and certainly doesn't seem to have been hung up on newness for newness' sake - as witness using the ancient Stroufley E tanks for the E1r rebuilds (rather than a new design for the duty) or the "bitsa" nature of the Z tanks. So I'm sure that had he felt the N class would have been the best solution, he would simply have built some more, twenty year old design notwithstanding.

Tom

 

Interesting that Collett too introduced an inside cylinder 0-6-0 at much the same time, albeit a much smaller and lighter one primarily for branch line usage. Does anyone here have access to the build cost for both the Ns and the Q class? Might be instructive. I suppose length and weight are other potential factors.

 

But why did he fit them with slide valves when pretty much everything else being built at that time had piston valve.

 

the Collett 2251 class were very ancient apart from the tapered belpaire boiler - with slide valves, loco links top suspended, and chassis based on the 1880s 'Dean Goods', which themselves harked back to much earlier Armstrong designs. there is no connection whatsoever between the Collett 0-6-0 and the much more modern Maunsell Q design.

there seeems to be a lack of info over the Qs plus some mis-information badly researched in the Oakfield biography of Maunsell. Holcroft doesnt mention them at all - which strongly suggests he wasnt involved or knew of the design process at all (and he been so, the valve gear might have been quite different plus the cylinders - as he designed the L1 valve gear and the cylinders/piston valves!)

what is even more remarkable is that Bulleid, having critisised the Q as being 'out of date' then used the chassis motion and cylinders without any alteration at all on his Q1s!

the Bluebell have done a wonderful job in getting the Q back into service!

cheers,
julian

 

Then Bullied built the best and most powerfull 0-6-0 to run in the uk seeing that in the future trains would be all fitted so there was less weight required in locos to provide breaking force.

 

Wasn't suggesting a design connection between 2251 and Q. But I find it interesting that both lines, with excellent and successful outside cylinder 260s, found a need to revert to inside cylinder 060 designs.

 

Unfortunately, that never transpired, hence the reputation the Q1s acquired for poor braking performance. Given that mechanically, the Q1s and Qs were closely related, I suspect the reputation for poor brakes on the Q1 when the Q had no such reputation is more because the Q1s could pull bigger loads but without enhanced braking capacity.

HAV Bulleid wrote the following about the Q1 brakes:

The Western Section S15s of course had double-bogie tenders.

Tom

 

And I think the brakes on the NYMR's S15 are pretty poor, double-bogie tender or not!

 

Given that Bulleid's pacifics also have a reputation for being a bit of a handful on loco brakes only, I'd hazard a guess that the Q1 brakes aren't too special either. A Q1 would have to tow around an extra Queen Mary brake to have as much weight on braked axles as an S15 (and it would still be lighter overall).

 

Well if their really no good, I'm sure there are people who will be more than willing to take them off their hands...