Piston valves

[Compound2632]

A question arising from a combination of ignorance and curiosity, with a dash of Derby snobbery thrown in for good measure:

 

What was the first class of Great Western locomotives to be fitted with piston valves?

[PenrithBeacon]

https://en.wikipedia.org/wiki/GWR_3700_Class_3440_City_of_Truro

Not claiming that this is the first, but it seems that the City class locomotives were converted from slide to piston c1914-16 consequencial to superheating. I would imagine that similar processes were at work with other GWR classes but that these classes were being dealt with concurrently so the answer to your question might be difficult.

I would guess that the first Churchward design would be the Saints and that would be a good approximation. But I'm not sure.

https://en.wikipedia.org/wiki/GWR_2900_Class

Looking at this the OP is really one of was there a GW locomotive before the Saints that had piston valves?

Edited August 3, 2020 by PenrithBeacon
Link added more words

[Jeremy Cumberland]

I think the Atbara class (4-4-0) were the first in 1900, but piston valves weren't fitted to all of them from new, and apparently this first incarnation of piston valves wasn't a success (http://www.gwr.org.uk/no440s.html).

 

It is also possible that the 3600 class of 2-4-2T were built with piston valves. The prototype, No. 11 built in 1900, certainly had piston valves but I am not sure about the production locomotives built in 1902-1903.

 

The Saints appear to be the first major class built with piston valves. The works photograph of 181 Ivanhoe, one of the first batch built in 1905, shows what appear to be piston valve covers.

[Chrisbr]

According to RCTS 4 coupled  tank engines - "Nos. 3600-20, except No.3614, were built with 6 1/2 in, diameter piston valves, which were placed between the cylinders." The rest were all built with slide valves and all those with piston valves had been recyindered by 1908,

[JimC]

Some 2721 saddle (later pannier) tanks were built with piston valves from Feb 1901. RCTS records that "piston valves had been experimented with from 1899", but I haven't managed to identify the earliest fitment. It seems well established that they weren't fully satisfactory until Churchward introduced the semi-plug type from the US.

Edited August 3, 2020 by JimC

[The Stationmaster]

The first of the Krugers' which came out of Swindon in December 1899 seems to have been the first,  Then - as far as tender engines are concerned - the first main batch of  20 'Aberdares built between March and June 1901 then a batch of 'Atbaras'  outshopped from July 1901.   In the early days Swindon was using two different sizes of piston valve plus experimentation with several different arrangements.

[Compound2632]

Earlier than Crewe, the, where piston valves were first used in conjunction with superheating on the George the Fifth class - and, I suppose, for strict accuracy, also without superheating on the ten locomotives of the Queen Mary class. Swindon seems to have been experimenting with piston valves well ahead of superheating.

Edited August 4, 2020 by Compound2632

[The Stationmaster]

On 04/08/2020 at 20:59, Compound2632 said:

Earlier than Crewe, the, where piston valves were first used in conjunction with superheating on the George the Fifth class - and, I suppose, for strict accuracy, also without superheating on the ten locomotives of the Queen Mary class. Swindon seems to have been experimenting with piston valves well ahead of superheating.

Yes,  Swindon started using piston valves in the Dean era although to what extent Churchward's inters was involved is not clear.   Superheating experiments only came along in the Churchward era - when several different types and arrangements were tried - and of course all sorts of other experimentation was taking place in a search for improved power and efficiency.   I have long held the view that Churchward was very careful with superheat temperatures (basically no more than steam driers perhaps?) because he came up against the problems being experienced else where with higher temperatures and even various different designs of piston ring could not overcome the lubrication problems which were common in early high temperature superheated engines in Britain.

 

It's interesting of course that when the use of higher temperature superheating finally arrived at Swindon lubrication problems immediately resurfaced and could only be solved by changing to mechanical lubricators (which had to be bought in) instead of relying on what was otherwise the perfectly satisfactory system of hydrostatic lubrication developed  back in Churchward's time and which was manufactured in house with no fees payable to anybody else.

[JimC]

5 hours ago, The Stationmaster said:

  I have long held the view that Churchward was very careful with superheat temperatures because he came up against the problems being experienced else where with higher temperature

Yes, its easily forgotten that Churchward's early superheated locomotives had higher superheat. The first installation on 2901 had 3 rows of 8 flue tubes in a Schmidt superheater arrangement with 308sq ft heating surface, and 2922's first had 3 rows of 6 in a Swindon designed arrangement for 275 sq ft. The std Swindon superheater for the Std 1was 2 rows of 7 flue tubes for around 260 sq ft (330 for one group with 8 elements per flue rather than 6). Oil consumption was such a big item that it was reported to the board.

[Il Grifone]

Excellent engineering! Keep it as simple as possible. Extra complications are only worthwhile if they bring a valid improvement.

 

For example, how many useless/annoying features has your computer?

My pet hate is how Windows now sorts your files how it wants them and not how I want them.

One of the many new, exciting changes brought in with 'Vista' IIRC. 'XP' was a classic example of. "If it ain't broke, don't fix it!"

Edited August 10, 2020 by Il Grifone

[Compound2632]

All very interesting and enlarging my knowledge of this rather confusing - and hence really most interesting - period of Great Western locomotive design. I wonder what prior examples the Swindon LDO had in front of them in drawing up their piston valves? S.W. Johnson at Derby had used his good friend W.M. Smith's patent piston valves in the 179 Class 4-2-2s of 1893 and all subsequent express passenger designs. Smith was chief draughtsman at Gateshead but the North Eastern was a little slower to adopt piston valves - one of the Class M1 4-4-0s of 1893, was given them as an experiment, then the Class J 4-2-2s when rebuilt from compound to simple from 1895 onwards but the first application to a whole class from new seems to have been the Class R 4-4-0s of 1899. 

[JimC]

57 minutes ago, Compound2632 said:

 I wonder what prior examples the Swindon LDO had in front of them in drawing up their piston valves? 

Dusty Durrant reckoned the US company Brooks Locomotive Works to be very influential. He stresses the importanc of combining piston valves with straight direct ports. 

Edited August 12, 2020 by JimC