Help with 'Speedy' valve gear and other issues...

[David]

Interesting info about the snow!

I have the injector book and I know I can solve the water temperature problem with ice in the tender, which I will no doubt have to do at least once over the next 3 months. Usually Jan and Feb.

I was just having a dig at the 'a pair of injectors is enough for anyone' guys (hi Julian ;) which my own club seems to be filled with. I don't have any pumps on my little loco and given I have not been able to get the water circuit air-tight or debris free in two years of slowly rebuilding it from filter onwards, I am somewhat skeptical of the idea. I spend more time looking at the injector overflows than the track, and that ain't right. And have had to come off early many running days because the damned things just won't work.

I know my workmanship is the problem but a pump would be a comfort. All my workshop time is taken with the B class so not spending it on water pumps.

[Roger]

Ok, that's the last of the modifications to the LH frame. There are still some unwanted LBSC holes that I need to fill in, but basically it's pretty much done. The RH side needs a few more holes because the drain cocks go along that side.

I forgot to mention that I've added a couple of 4mm dowels that will connect the cylinders with the frame. I've been told that cylinders can work loose, so this ought to take away any chance of them sliding on the frame faces.

20181203_214133 by Roger Froud, on Flickr

[ettingtonliam]

Dec 3, 2018 8:30:59 GMT @greenglade said:

I recall reading somewhere about the use of the reverser being preferred to the regulator due to design changes.. early loco's (19th and early 20th century, in general, using the regulator and later more modern (perhaps after 1920's) using mostly the reverser. Alas, I can't remember what changed this, I do recall it was to do with better design/technology.. perhaps slide valve, vs piston valve?... I just can't recall the details. Others with more knowledge (better memory) than I will be able to give a more informed answer. I do know that Gresley pacific's were generally driven on the reverser with wide open regulator used for the entire journey bar stop/start. Again, in one of my books, there are some charts giving details of regulator vs cut off used throughout an entire journey along the East Coast mainline and for comparison the same journey using the regulator. I recall some comment about driving on the regulator is more 'old school' and that, modern locomotives (we are talking 20's-30's onwards) being driven mainly on the reverser.

I still have very little driving time being too busy on 4472's build to play trains with 4470, I have, however, driven 4470 on the reverser and she drives very well and can be notched right back easily.

Pete

I think the older` practice of driving on the regulator rather than on the reverser came from the era of short travel valve gears becuse although they could be notched up, it wasn't by very much. With the advent of long travel valve gears in the first 25 years or so of the 20th century came the ability to be able notch up effectively. Assuming that most of our model locos will (or should) have reasonably effective valve gears, then they should be capable of being driven the same way.

[chris vine]

Also, with slide valves, if you have the regulator fully open with the valve gear well notched up, then the pressure on the back of the valve makes a huge forces - several tons. The friction wastes power and also wears out the valve gear.

With piston valves, this is not an issue. Pistons valves came later, so this probably helped to move towards driving on the reverser in later years.

Chris.

[jma1009]

Hmm..

Perhaps a new thread to be started on'How to drive a miniature locomotive' to avoid serious thread drift from Roger's excellent thread?

My point was that Roger was quite correct with his plan for the bypass outlet pipe as he would not be able to lift up a tank filler lid 'on the run' and to see this.

Personally, and there is more exciting stuff anticipated, I don't think Roger will ever need to use the axle pump. Hand pumps and axle pumps are a throw back to 2.5"g locos where injectors in this scale were unobtainable.

100% reliable injectors are available in the UK from Paviersteam via Len Steel, usual disclaimer.

Cheers,

Julian

[JonL]

Dec 3, 2018 23:17:06 GMT jma1009 said:

Hmm..

Perhaps a new thread to be started on'How to drive a miniature locomotive' to avoid serious thread drift from Roger's excellent thread?

Agreed, thats a great idea, and sorry Roger for cluttering it up!

[pault]

Dec 3, 2018 23:17:06 GMT jma1009 said:

Hmm..

Perhaps a new thread to be started on'How to drive a miniature locomotive' to avoid serious thread drift from Roger's excellent thread?

My point was that Roger was quite correct with his plan for the bypass outlet pipe as he would not be able to lift up a tank filler lid 'on the run' and to see this.

Personally, and there is more exciting stuff anticipated, I don't think Roger will ever need to use the axle pump. Hand pumps and axle pumps are a throw back to 2.5"g locos where injectors in this scale were unobtainable.

100% reliable injectors are available in the UK from Paviersteam via Len Steel, usual disclaimer.

Cheers,

Julian

That could be an interesting thread.

I agree that very reliable injectors are available and in reality have been available for many years.
My experience is that the injector is seldom the problem when it fails to work. On a new loco that has never had a reliable injector it is very often the pipe runs or size that are at fault. There was one BR Std 7 that had the injectors mounted on brackets attached to the firebox cladding, they would only work after letting the water run through them for ages to cool them.

Many people say about ball lift in clacks but I have never found this to be an issue. I did make a clack with an externally adjustable stop so the lift could be changed whilst the injector was operating. You almost had to press the ball onto the seat to stop the injector working
On older locos air being drawn into the plumbing is a favourite from leaking water valves, flexible pipes (you can’t white beat silicon tube just pushed onto copper pipe) and the like. I have seen a couple of tenders where the axle has rubbed a hole in the copper water feed pipe. Its amazing how many people have water dripping from water taps or pipe joints but can’t see how it could cause a problem. Injectors suck, so if water can leak out they can suck air in, which they do not like.

Injector problems can be common after a loco has been laid up for the winter. My theory on this is that the dirt and scale dries out and flakes off the inside of the tank. A good cure for this is to stick a hose in the tank, turn it on full and move it around in the tank. Allow the water to flow out of the filler, you may be suppressed just how much crap gets carried out by the water overflowing.
“Blowing back” an injector can often give a temporary fix if there is a lot of dirt floating around. Block the overflow with a rag on the end of a pricker or something similar, turn on the steam then open the water valve. Wait until you hear the steam rattling in the tank. Turn off the steam, let the water run for a minute then try the injector.

Regards
Paul

[dscott]

Well over the weekend I completed the extra stops on the newish mill, biting the bullet and drilling into the base 4 holes and 1 hole in the saddle the other for the bar that moves up to the stops. This held the second saddle lock!
Of course even having the longest travel to date on any mill for this size it still can't do a complete run so forward planning was needed? Yes, mill so far and fit 2 blocks so that the frames could be slid against and milled up to the stop. Giving a continuous cut.
Then the bottom could be done in two goes.

THE INTERESTING SIZE COMPARISON TO A LARGE PRAIRIE TANK FRAME?

For this is what I had left over from the summer when a waterjet cut one came into my ownership plus boiler And set of castings (Abandoned)
Now has anyone wondered exactly why everything is shoved up together on a 15XX?
I thought so. well Mr Hawksworth pondered some new locomotives and although the Large Prairie tanks were superb in the Suburbs they were sods to oil round with a reducing workforce unwilling to get inside and oil and check so put everything outside.
"What have we got in the surplus frames stock?" must have been answered by "Big Prairie Frame un-joggled!"
I know what they meant. I have a Joggle tool but no huge press yet to do them hence (Abandoned)
A quick clean up all round and several shifts along resulted in the marking out beginning in the warm of the sitting room.
My reduced Paddington drawings show 92 mm wide, or 5/16 less than the Speedy putting it in line to use the slimmer 51XX frames.

So we now all know why you can't slide a modern mobile between the parts on 1501. It was all cramped in to fit what they had in stock... And this now goes on to explain the size of cab. TINY!!!

David rewriting history 1984 style now we have the measurements!
Only Roger knows how many tiny holes I need to drill over the next week!!!

[jma1009]

Hi David,

Not sure I understand any of the above!

The 15XX was Hawksworth's only departure from Churchward design precepts, and at the time and until withdrawal was regarded as a 'non standard' expensive failure.

Actually, in miniature, if suitably modified, it has proved to be far more successful than in fullsize, and the SVR have found it's own unique survivor to be very capable trundling along at a max of 25 mph.

The essential problem in miniature is that LBSC did not understand - or fudged/bodged the very close proximity of the upper pin links in the combination lever. In fullsize you can clearly see this, plus the valve rod guide omitted by LBSC.

I fail to see the comparison with a 51XX chassis. Note the 15XX was the only loco built by the GWR with inclined cylinders, another detail LBSC omitted.

Cheers,

Julian

[Gary L]

Dec 5, 2018 0:13:17 GMT jma1009 said:

Hi David,

Not sure I understand any of the above!

The 15XX was Hawksworth's only departure from Churchward design precepts, and at the time and until withdrawal was regarded as a 'non standard' expensive failure.

Actually, in miniature, if suitably modified, it has proved to be far more successful than in fullsize, and the SVR have found it's own unique survivor to be very capable trundling along at a max of 25 mph.

The essential problem in miniature is that LBSC did not understand - or fudged/bodged the very close proximity of the upper pin links in the combination lever. In fullsize you can clearly see this, plus the valve rod guide omitted by LBSC.

I fail to see the comparison with a 51XX chassis. Note the 15XX was the only loco built by the GWR with inclined cylinders, another detail LBSC omitted.

Cheers,

Julian

Julian is right of course. And judged with hindsight, it is strange that (for example) completely new cylinder patterns* and non-standard motion parts were ordered for just ten locos. I can only suppose (without a shred of evidence) that Hawksworth had in mind developing a series of new standard outside-cylinder small locos, e.g. to replace the elderly Dukedogs, but the idea was stillborn with Nationalisation. (There is rather more evidence that he did this with the County class, whose driving wheel patterns were to be shared with a hoped-for Pacific.) We will never know for sure.

-Gary

*pattern singular actually, there was only one cylinder casting, duplicated each side.

[delaplume]

Dec 5, 2018 0:13:17 GMT jma1009 said:

Hi David,

Not sure I understand any of the above!

The 15XX was Hawksworth's only departure from Churchward design precepts, and at the time and until withdrawal was regarded as a 'non standard' expensive failure.

Actually, in miniature, if suitably modified, it has proved to be far more successful than in fullsize, and the SVR have found it's own unique survivor to be very capable trundling along at a max of 25 mph.

The essential problem in miniature is that LBSC did not understand - or fudged/bodged the very close proximity of the upper pin links in the combination lever. In fullsize you can clearly see this, plus the valve rod guide omitted by LBSC.

I fail to see the comparison with a 51XX chassis. Note the 15XX was the only loco built by the GWR with inclined cylinders, another detail LBSC omitted.

Cheers,

Julian

Hi Julian......Have you been rolling that "Wacky-baccy" again ?? LoL !!}------- Quote}--"Note the 15XX was the only loco built by the GWR with inclined cylinders, another detail LBSC omitted."........Er, not so old mate !!......From personal, hands-on experience I can confirm that the following are all Ex-GWR and have inclined cylinders}---2251 class ( 3205 at SVR).-- 56xx ( 5619 at Horsehay ),...57xx
( 5764  at SVR ), ..... 

In the first photo ( 3205 ) I actually white-metalled, re-machined and fitted that R/H Cross-head whilst one of the full-time staff did the other one.....


My understanding of the 15xx existance was purely for Empty stock shunting at Paddington .......As you mention the 25mph it's because of the huge "Tail-wag" that develops at speeds higher than that due in part to it's short wheelbase coupled to 2, fat, outside cyls................

One line of thought has it that the outgoing GWR Board wanted to spend the last remnants of cash before the new British Railways people took over....Urban myth but -----?

[Roger]

It surprises me that the GWR persisted with inside cylinders when you consider what a pain that arrangement is to maintain. The only reasons I can think of for doing that, besides not changing things, is that you can have a shorter locomotive and use Stephenson's valve gear to give equal performance in both directions?
The cost of making a crank axle and the extra parts for the valve gear doesn't seem to have been enough to precipitate the change.
Doubtless those in charge had reasons that seemed sensible too them at the time. Change doesn't usually happen without a compelling reason to do so. Perhaps the tipping point was reached with 1501 with the requirement for more power. That's not easy to achieve by simply increasing cylinder diameter when they're between the frames. Increasing pressure would have meant a new boiler design too, so maybe this is why outside cylinders were adopted. I'm assuming they are bigger in diameter or have longer stroke of course, and that might be wrong!

[mbrown]

Surely there are lots of good reasons for choosing inside cylinders for a "general workhorse" loco.... Three parameters would be important (apart from power itself) - length, weight distribution and stability on the road. An inside cylinder loco can, as Roger notes, be made shorter with a smaller front overhang and the cylinders giving a better balance to the weight of the firebox at the rear. With the drive between the frames, the tendency to "box" as noted on the 15XXs is reduced. You get a compact, relatively powerful and stable, loco with no need to worry about the complexities of carrying wheels, pony trucks etc.

[mbrown]

(... not sure what happened there. Seem to have sent the post by accident before I finished....)


The 15XXs were apparently designed to have a deliberately short wheelbase for access to sharply curved tracks. That would have made inside cylinders tricky to fit in without making the connecting rod very short and angular. The price Hawksworth paid was a loco with a tendency to box - and thus to damage the track - and probably some difficulty getting the weight distribution right on all three axles. Plus, as noted, the need to design new parts, invest in patterns etc.


I think all locos built for docks and tight curves - apart from 0-4-0s - had outside cylinders. Caledonian (Rob Roy), LMS (Twin Sisters) and so on. But it was a compromise solution for a specific set of traffic requirements. The inside cylinder 0-6-0 was compact, balanced and short in relation to its power. Beyond a certain size, or speed requirement, carrying wheels become a necessity, and then the advantages for inside cylinders over outside ones become more marginal. I don`t think the choice of Stephenson`s valve gear has much to do with it - although it is undeniably convenient with inside cylinders.

Malcolm

[pault]

There is always the obvious answer... the GWR did it because they would never do what others were doing. Takes cover 😀

[delaplume]

and you'll need to because the Flak will be coming from 2 opposing camps I think !!

[jma1009]

Hi Alan,

My apologies - meant to type "inclined outside cylinders" instead of "inclined cylinders". As you know, Churchward would not countenance inclined outside cylinder locos.

Cheers,

Julian

[delaplume]

Dec 5, 2018 8:26:52 GMT Roger said:

It surprises me that the GWR persisted with inside cylinders when you consider what a pain that arrangement is to maintain. The only reasons I can think of for doing that, besides not changing things, is that you can have a shorter locomotive and use Stephenson's valve gear to give equal performance in both directions?
The cost of making a crank axle and the extra parts for the valve gear doesn't seem to have been enough to precipitate the change.
Doubtless those in charge had reasons that seemed sensible too them at the time. Change doesn't usually happen without a compelling reason to do so. Perhaps the tipping point was reached with 1501 with the requirement for more power. That's not easy to achieve by simply increasing cylinder diameter when they're between the frames. Increasing pressure would have meant a new boiler design too, so maybe this is why outside cylinders were adopted. I'm assuming they are bigger in diameter or have longer stroke of course, and that might be wrong!

What's more amazing is that at that time they could have bought a very similar loco "off the shelf" from America---------ie the USA type that the Southern had shunting at Southampton Docks............................http://www.bluebell-railway.co.uk/bluebell/pics/usa.html



OR}--- bought /hired some embryo Class 08 Diesel shunters from the LMS....for short term use...They already had these }--------    en.wikipedia.org/wiki/GWR_diesel_shunters


Question for you---- apart from The Duke of Gloucester, why did the British Transport Commission call for all the Standard range of locos to be outside cylinders with Walshaerts valve gear etc ??


Answer = COST reductions via simplicity of design..!! As Roger pointed out a crank axle is an expensive bit of kit  to make.....Also maintenance costs were rising, the labour pool was diminishing and turnround times in the workshops were being reduced.....

[Gary L]

Dec 5, 2018 8:26:52 GMT Roger said:

It surprises me that the GWR persisted with inside cylinders when you consider what a pain that arrangement is to maintain. The only reasons I can think of for doing that, besides not changing things, is that you can have a shorter locomotive and use Stephenson's valve gear to give equal performance in both directions?
The cost of making a crank axle and the extra parts for the valve gear doesn't seem to have been enough to precipitate the change.
Doubtless those in charge had reasons that seemed sensible too them at the time. Change doesn't usually happen without a compelling reason to do so. Perhaps the tipping point was reached with 1501 with the requirement for more power. That's not easy to achieve by simply increasing cylinder diameter when they're between the frames. Increasing pressure would have meant a new boiler design too, so maybe this is why outside cylinders were adopted. I'm assuming they are bigger in diameter or have longer stroke of course, and that might be wrong!

Hi Roger

We can only guess. It is important to remember what a highly successful family the GWR pannier tank family were; and although we tend to think of the Churchward standards in terms of the outside-cylinder classes, the pannier tanks, especially the later classes, also constituted a GWR standard, and the largest one numerically by a very large margin. But in the main, even the most up-to-date dated from the late 20s and early 30s when labour was plentiful, and cheap, and inside cylinders generally gave better roadholding at speed, which is very important when the loco has no guiding wheels.

When the GWR tried to 'modernise' the standard pannier tanks, the results were not especially happy. The 94xx were strong locos, but too heavy, and the modern taper boiler with Belpaire firebox (virtually the same as the 15xx) necessitated a wider cab, which made them less useful for shunting than they should have been.

It is a matter of record that Hawksworth decided on outside cylinders for the 15xx primarily for easier maintenance and thus greater availability in post-WW2 conditions: "the 24-hour shunting locomotive." Unfortunately a better 24-hour shunting locomotive already existed on other lines in some numbers, particularly the LMS, and they were powered by diesel engines, so the 15xx was doomed before it was built. We can see that now, but it wasn't so obvious at the time.

One canard that must be disposed of altogether is the suggestion that the 15xx was part of some pre-Nationalisation spending spree. There is no evidence at all that railway officers before or immediately after Nationalisation took such a nihilistic attitude to their responsibilities. Things were different then; the country was on its knees after a devastating war, and waste of any kind was socially unacceptable. More to the point, the early drawings for the 15xx are dated 1944, well before the General Election of 1945, and at that early date the prospect of a Labour victory ousting Churchill and ushering in Nationalisation was utterly unthinkable. (It was shocking enough for many people when it actually happened!)

No, I am firmly of the view that in 1944 Hawksworth foresaw a wider use for the new parts built into the 15xx. He had been brought up in the Churchward Drawing Office; he knew the value of standardisation, but he also knew that there were aspects of the Churchward scheme that needed to be swept away. The gigantic cylinder + half-smokebox saddle casting and the weak forward extension frames necessitated by it were one such, and he showed his intentions very clearly in the "Modified Halls" and the Counties. It seems a perfectly natural and logical progression to do the same thing with the smaller engines, and the 15xx would have been a perfect testbed for these parts, if history had turned out differently.

All speculation. I might well be wrong; but I think we are way beyond proving it, one way or the other...

Best regards

Gary

[jma1009]

Hi Gary,

I think things are bit more complex. Churchward never built any 0-6-0 tanks other than the few replacements for the Cornwall Railway locos, when he rolled out the original drawings for Harold Holcroft, and tasked him with designing the replacements, which were pretty much a copy of the originals with Allan valve gear.

Churchward otherwise had enough Armstrong and Dean 0-6-0 tank locos to fulfill duties.

Collett had to do something about the absorbed South Wales companies post 1923 - the Rhymney, Taff Vale, and Barry Railways principally. The 56XX was the result. Then Collett had to do something to replace the by then worn out Armstrong and Dean 0-6-0 tank/pannier tank locos; the 57XX using a chassis of 1880s vintage was his response. To replace the Armstrong 'Standard Goods' 0-6-0 tender locos, the 2251 class (using the same chassis as the 57XX class and dating back to the 1880s) was built.

Hawksworth designed the 94XX 0-6-0 pannier tanks apparently due to a comment from a member of the Locomotive sub committee of the GWR board - it was a 57XX with a tapered belpaire firebox boiler on again a 57XX chassis of 1880s vintage!

I don't think anyone knows why Hawksworth designed the 15XX as per 'Speedy'. If they were to go round Newport Docks, they were never used for this purpose! They ended up pretty much nearly all the class at Old Oak Common steaming in and out of Paddington hauling empty coaches a short distance, which a 57XX and a 94XX were quite capable of doing.

Cheers,

Julian