GWR 94xx Pannier Tanks, ex-Edward Thompson Thread.

Interesting comment, though put it this way.
If circumstances were flipped, would the SR borrow the 15xx design for the USA tank or buy up 15xx surplus?

 

The design aim was a 24 hour shunting engine which didn't need to go over a pit for oiling. They were actually split between Paddington and South Wales. Unlike the 94s though the concept was really made obsolete by the success of the early diesels at the pure shunting role, which no doubt explains why no more were forthcoming.

 

This is exactly why the Great Western were, as the name says, Great.
Tried and tested methods that proved successful and we never changed it, you just recycle the engines round it, no wonder they are the easiest to maintain and work on.

 

Thanks - forgot about oiling up. I guess it meant they could hire humans, rather than midgets with 8' long arms to oil up.

Coal capacity would've been a consideration as well I would've thought. If a 15XX can do a whole shift without needing to go for coal, why would you buy an S100 that would need coal before a crew change?

 

An interesting question. No doubt others will be far more knowledgeable than me but , from conversations with retired shed maintenance staff, the GWR running sheds carried out quite a lot of work. Swindon built the engines and carried out the heavy generals however there were a number of other places that were also referred to as "works" eg, Oswestry, Caerphilly, Worcester, Wolverhampton, Tyseley , Old Oak. Newton Abbot and probably more that I'm not familiar with. These had purpose-built workshops (factories), in addition to the running shed, where the more extensive work was undertaken. Reference Kenneth Cook's book where he quotes that the objective of a heavy general at Swindon was to return the loco to "as new" condition.

Running sheds ,as opposed to sub-sheds, were all provided with lifting gantries ( for some reason the GWR used very few wheel drops so even a Castle got heaved up at an alarming angle) and a selection of machine tools and workshop equipment together with the necessary skilled staff, all of whom did some of their apprenticeship training at Swindon ( continuity of central standards) . Valve and piston exams, repairs to axleboxes, motion and valve gear bearings would all be dealt with by the running sheds as well as the host of other things that went wrong on a day to day basis. Boiler washouts , inspections and light repairs would also be at the running sheds with components being exchanged in the event of failure. Taking out superheater elements to deal with leaking headers would be a regular task . Even replacement of tubes and stays and the application of patches to fireboxes would be a regular job if it would keep the loco in service until the next booked visit to a works. Not GWR but Bill Harvey's book about his time at Norwich gives a good insight.

The extent of work carried out by the outstation "works" may have varied. eg for Tyseley the chap I talked to referred to it as a "sole and heel" job, rather than the full heavy general for which the loco would have gone to Swindon. I think the GW classification for repairs went something like "light", "intermediate" and "heavy general".

Getting back to boilers there are photos of something being re-tubed at Truro shed and the owner of a , very small, engineering business in Truro who did a lot of boiler repairs around the county, told me that he was regularly called to Truro shed to make repairs to engines that had failed a boiler inspection , even to the extent of fitting patches to fireboxes. he was authorised to order tools and parts from Swindon. Newton Abbot had extensive facilities but I wonder to what extent they would have tackled a major boiler rebuild eg replacement of firebox, wrappers, barrel rings ? Would this only be done if a spare boiler was not available from Swindon? It occurs to me that the amount of work and the approach varied according to local circumstances.

With regard to parts, bear in mind that there was a very large central stores at Swindon with large stores at all of the other works so if something at Penzance or Aberystwyth required replacement parts these would be on a train in a very short time. If you have a look at the maintenance records for any steam loco the amount of time spent under repairs is quite an eye opener , also the relatively short life of fireboxes and tubes. You then begin to understand why such a large repair organisation was required and also why Swindon didn't always have capacity to built new locos , hence the use of the contract loco builders.

Returning to the 94xx ,K Cook refers to this as "rather a tragedy" and opinions that Hawksworth should have stood his ground and built another 200 of the 57xx class!. He ( Cook) quote four disadvantages; the wider cab made it very difficult for the driver to reach the brake valve when leaning out of the cab ( after a lot of complaints modifications were applied) , the heavier boiler raised the axle loading from "blue" to "red" , from the construction point of view the design of the cylinder block was more complicated and required extra work and expense in the foundry, finally a 57xx firebox could be built up and riveted by hydraulic power and then fitted to the boiler shell whereas the belpaire box of the standard 10 boiler used for the 94xx had to be inserted in sections, welded in place then largely handed riveted using wedge-riveting techniques. He also refers to the 15xx as being designed especially as a 24-hour shunting engine which did not need to go over a pit for oiling. Servicing an Austerity tank without a pit is a bad start to a day!

 

Would the 56xx 0-6-2 tanks not have done for ECS at Paddington?

 

I'd merely point out that there were 9 S100s still in use in March 1967 and 4 in use at the end of Southern steam. I think that is a pretty good return on investment.

What I find ironic is the whole defence of building GWR designs in the name of standardisation, a policy that then goes completely out of the water when it comes to dieselisation and the completely non-standard designs used. Or were they also standard but just in the west? Won't somebody think about the storemen?

 

They probably said the same at the transition from Dean to Churchward.

And hollow laughter from those earlier storemen who had to keep 2 different lengths of axle in stock...

 

There's going to be an, if you like, critical mass, where the benefits diminish. If you have to keep one of each of 20 lines that's an issue, but there's less to be gained if you have two lines that you need to keep 10 of each or 3 lines and 10/5/5.

 

I would personally take the view that there as many issues with the Hawksworth 15xx as with his 94xx.

Model Engineers have spent 70 years trying to get to grips with the 15xx walschaerts valve gear. And run it on computer simulations. The 94xx has an ancient pedigree for it's valve gear.

The USA tanks had a much better valve gear geometry and envelope than the 15xx.

I just think that Hawksworth was using up his budget otherwise the GWR shareholders would not get from the Labour Government on Nationalisation the compensation agreed.

 

Considering the limited RA of a 94xx. What would the RA of an Austerity and an S100 have been?

 

The 15s had a long gestation though. The NRM has some early proposals for what became the 15xx, and the earliest is dated February 1944. If I read the descriptions in the NRM drawings list correctly it looks as if the design was finalised at the end of 1944. It appears they were designed before the 94s.

 

They're more comparable with a 57 than a 94 though. Unless you subscribe completely to the story about domes, the 94s (and remember the last lots of 57s were built concurrently with 94s) must have been intended to have capability greater than the 57s. And as I expect I've said above the obvious differences between the two are greater adhesive weight/brake power and more boiler capacity. Remember they were intended primarily for the Welsh industrial areas where AIUI all the routes were red restricted. Indeed some of the absorbed Welsh classes were over the standard red route axle weight. The Austerities and USAs were *at best* no more capable than a 57 - indeed the KESR web site used to state that their 16xx was about equal to an Austerity, let alone a 57.

 

The WR standardised on 3 designs of diesel hydraulic-101 hymek, 61 Warship and 74 Western. At the time, these were proven proven technology in Germany. Those 3 types, DMUs and a bucketful of 09 08s would have sufficed for the whole of the region. That really does go along with a standardisation policy. It just doesn't go along with everyone else's thinking.



At the same time, British Railways board ordered:

635 small shunters under 300 hp, 18 different types

1412 shunters, 300-799hp, 15 different types

455 Type 1 locomotives, 800-1000hp, 12 different types

1109 Type 2 locomotives, 1001-1499hp, 11 different types

508 Type 3 locomotives, 1500-1999hp, 3 different types

393 Type 4 locomotives, 2000-2999hp, 5 different types



Most of these ranged from woefully inadequate to simply garbage, and from the 64 different types, about 8 actually made the grade. The decision to standardise diesel-electric instead of diesel hydraulic was made by the LMS-centric British Railways management, as a political decision, rather than one based on actual shortcomings of diesel hydraulics which were pretty reliable (as far as I have read-I am really not interested in diesel trains)

When compared with the baby-deltics, metrovicks, BTH type1(TopsCl15),NBL Type1 (Cl16)Clayton Type1 (Cl17), (need I go on ?) all of which distinguished themselves with truly execrable reliability, and bearing in mind BR went on to order another another thousand or so diesel electrics of a half dozen different types, does the ten year operational life of the diesel hydraulics seem such a failure?

 

Doing a bit of number crunching, it seems to me that the J94 and S100 were definitely locos of one type; and the 57xx and 94xx were locos of a different type; and the 15xx seems to sit uncomfortably between, being neither one nor the other.

Here's the numbers for the five designs, comparing some physical characteristics (weight, wheelbase, minimum curve radius); some boiler parameters (grate area, firebox and tube heating surfaces); and some derived numbers (notably Tractive Effort, and - I'll explain - the ratio of firebox and total heating surface to swept cylinder volume). Figures are from Wiki except the boiler dimensions of the GWR types which come from @Jimc's website:

So first if you compare the J94 and S100 against the 57xx and 94xx: on the one hand you have a pair of short wheelbase designs able to traverse very tight curves (less than 2.5 chains for the S100); on the other long wheelbase designs able to traverse "normal" curves (5 chains).

Also very notable, particularly on the J94 is a small firebox and large cylinder volume. If you take the firebox heating surface as a proxy for the rate of steam production, and the swept cylinder volume as a proxy for the peak steam consumption, then low ratios of heating surface to swept cylinder volume are essentially saying the locos are under-boilered (or over-cylindered). Take all those together and you have exactly what you'd expect for shunting locos: lots of tractive effort, but without the boiler power to sustain that effort; and short wheelbase to go round tight curves. Whereas the 94xx and 57xx are clearly designed to make sustained runs along the mainline.

Which leaves the 15xx, which seems to be neither Arthur nor Martha. It's got a short wheelbase - but not that short: the minimum radius isn't as flexible as the J94 or S100, but it isn't going to be as stable doing trip workings on the line. If it is designed for shunting, why the superheater which is basically an expensive and weighty hinderance? And why the boiler power to cylinder ratios equivalent to the 94xx and 15xx? But if it is designed as a line loco, why the short wheelbase?

(One other anomaly is that the S100 is the smallest of all of them, but has the biggest grate area. I suspect it was designed with poor coal in mind).

(Edited - see below)



Tom

 

Presumably an LMS Jinty would be comparable with a 57xx? The LMS did not build any more steam shunters after the Jinties, apart from a handful of 0-4-0 saddletanks and one Sentinel.

They went in for diesel traction for this work and the 08 was a development of the final LMS design.

On the western diesel hydraulics, I've heard that the WR drivers liked them and that they were excellent haulers

 

Oddly enough, it looks more like a long-wheelbase J94. Same cylinder size but a relatively small firebox, grate area and heating surface. The long wheelbase is odd for a pure shunting engine: I couldn't find a minimum curve, but presumably no better than the 57xx given an even longer wheelbase.

It has the Victorian feel of big cylinders / low pressure: 160psi against the 200psi of the other designs. Locos like that seem to keep on pulling strongly even if they go off the boil a bit, provided you don't completely muller them.



Tom

 

That's an interesting and useful bit of work Tom, thankyou.
The 15xx boiler wasn't superheated, it was an unsuperheated variant, also used on the outsourced 94s. The tube heating surface was 1246 sq ft so total 1348.
The Std 10 and the P Class (57xx) boilers were really the only choices from the standard range for a big 0-6-0 tank, but it would be very interesting to know why the larger and heavier Std 10 was preferred to the P class for the 15.

It has occurred to me that the 15xx wheelbase might be for other reasons than curves. My theory is this: having inside cylinders, the 57 and 94 cylinders are set partially between the wheels. The big outside cylinders on the 15 can't be, so the leading wheels have to be set back relative to the boiler to make space. Then the trailing wheels have to be set forward for the locomotive to balance. The 15 is heaviest on the leading wheels and lightest on the 3rd pair, whereas the 94 is opposite. Be interesting to know what someone better versed than I on the subtleties of steam locomotive designs makes of that idea.

Your work also inspired me to look at the numbers for the 1600, that at least one KESR writer has considered equal to the Austerity, presumably for trip work. The 16 boiler is 14.9 grate, 79.5 firebox, 8, 772 tubes so not a million miles from the Austerity as a trip locomotive, but with 41T weight and 18,500 TE, nowhere near it as a pure shunter.

 

Damn you GWR types with your standardisation that is no such thing

I've edited my post and table above - hopefully correctly.

Tom

 

Interchangeable != Identical!