LBSC's Rainhill

[robinw]

Hi all,

Following in other's example I thought I would just create a singular thread where I can ask any of the questions that come to mind as I attempt to build my first steam loco, and to post pics as things develop. Back when I was 16 I bought the drawings and 20 years later am finally at a point where I can start work.

I am expecting to take  a number of departures from the original drawings, as I want to hide a bit of weight into the engine and use slightly more up to date methods, where my limited equipment and experience will allow. 

The first of the two questions that come to mind while I work on the engine and tender beams, and pump stay are:

How big should the axle pump be? Reading through the forum, I get the impression that LBSC's standard sized axle pump on his smaller engines were quite oversized. Is there a best guided ratio for the maximum steam consumption of the loco at maximum speed versus input?

Mathematically speaking the current ratio seems to be about 15 times the maximum steam usage at 80psi for 11/16" x 1 1/8" cylinders doing 6mph at 85% cutoff. Surely it would be better to reduce the size of the axle pump so that it is more like 6-8 times greater than the maximum steam usage?

I'm thinking about reducing the size to 1/4" x 1/4" from 5/16"x 3/8" 

Thank you in advance for any advice given.

Cheers,

Robin

[joanlluch]

Hi Robin,

First of all let me start by stating I am no expert as I have yet to complete my first locomotive. However I have quite an interest into all theoretical aspects of steam locos and I have made a spreadsheets to calculate basic aspects of steam raising, fuel consumption, water consumption, required water pump size, and so on. On my spreadsheet I work on the basis of a 1.5x overcapacity for the water pump with respect to the theoretical maximum steam usage of the locomotive. The axle pump water supply is proportional to speed, but in practice the locomotive will not use that much steam/water for continued periods of time because you may run at shorter cut-offs and a partially open regulator. So that's why I considered only 1.5x capacity was required for the axle pump. In any case, you should have at least one more way to provide water to the boiler specially when the loco is stopped.

[robinw]

Hi Joanlluch,

Thanks for your thoughts. Definitely will be more than one water supply to the boiler. I thought it was a requirement that there were at least two functioning water supplies?

I just want to know how big or small the axle pump needs to be before I drill the hole for it in the pump stay.

Robin

[joanlluch]

Hi Robin, I'm not from the UK, but yes I think it is a requirement to have at least two separated ways to feed water to the boiler. Most people seem to rely on two injectors, a manual pump, and NO axle pump. Others fit the axle pump as an additional safety measure. In my case I am going for what I have seen people using in my Country. With temperatures in Summer above 35º injectors doesn't seem to be considered reliable enough. For instance max temperature in Girona area from next Tuesday to Thursday is already forecasted to be 36ºC and possibly rising over the following weekend. So instead of injectors we use steam powered donkey pumps almost exclusively. A manual pump in the tender is also a must in my opinion, and then a carefully sized axle pump can be considered optional.

[jma1009]

hi robin,

by all means fit a smaller axlepump, reducing the bore and outer diameter by 1/16".

Rainhill is not a common LBSC design, in fact it hasnt been listed in the old catalogues i have for over 30 years. i have never seen a completed example. unless you have progressed quite far with the build i would be inclined to build something a bit bigger and more well known and which is capable of hauling you such as LBSC's Juliet.

joan, Rainhill is a 3.5"g loco based on Stephenson's Rocket 0-2-2 loco. it has slip eccentrics and is a rather basic loco and the general principles about valve gears and expansive working wont apply to Rainhill.

cheers,
julian

[GWR 101]

Hi Robin, sorry can't help with the Rainhill but I am building a 3 1/2" Juliet. The drawings specify a 3/8" dia. pump ram with a 1/2", stroke following advice I have reduced the ram to 5/16" dia. As I had already machined and fitted the eccentric I have left the stroke at 1/2". I was advised to go down as small as 1/4" dia. but decided against this, as mentioned I understand at least two separate boiler feeds are required so I will be fitting an ejector and of course also have a hand pump.
Although unlike Joan we may not be subjected to prolonged periods of hot weather as my engine is a tank engine due to the possibility of the water in the tanks becoming warm (hot)I have decided to supply the injector from a large capacity tank in the drivers trolley. Hope this is of help, can't say how mine will work as it is still under construction but hopefully I will know by the Autumn. Regards Paul

[robinw]

Hi Julian,

Thanks for your message. Unfortunately my lathe and small mill won't cope with anything much bigger than the smallest of the 3 1/2" gauge engines. As this is my first attempt at building a steam locomotive, I wanted to build something that will give me a taste of what's to come, when I get onto building what I really want to build. I could have gone down the stationary engine and boiler route, but felt that a tinkered with Rainhill would fit the bill better, even if it in the long term it becomes a mantle piece model.

As I don't have any training in metal work/engineering I felt it was better to start with something very basic and achievable than to become another one of those who start an overly ambition project and give up.

Hi Paul,

Sounds like your Juliet is coming along nicely :-) good to know that people had suggested that you make your axle pump smaller. I just don;t see the point in fitting a way over sized pump if I don;t need to!

Thanks guys for your comments.

Robin

[alanstepney]

I have only seen one Rainhill, and, from memory, it would only haul the driver plus one (or perhaps 2) people.
Just what one would expect from a small locomotive.

Good luck with the build.

As for machine V model size, it is surprising how much one can do with small machinery.

[GWR 101]

Hi Robin, apologies in advance if I am telling you something you already know. Whilst ordering some parts for my build I notice that GLR Kennions on line catalogue list some parts for a 3 1/2" Rainhill (usual disclaimer other than a satisfied customer). If this is news to you and you are determined to build this loco I would certainly give them a phone call as I have always found them most helpful.

It certainly looks a like head turning loco but as Julian and Alan states it's pulling capacity may be limited. I would not want to even appear to question their knowledge and experience as it is far in excess of mine, but at the end of the day the decision is yours, so good luck with what ever project you embark upon. Regards Paul

[robinw]

Thanks Alan and Paul for your messages.

I've been using GLR for a number of years getting the few bits of metal that I've needed for building harps, and was indeed where I've procured the castings for Rainhill. Mostly they look ok, though there are a few I think I'm not going to bother with using and will fabricate instead.

I'm fully expecting the hauling capacity to be limited, after years as a late teenager and in early twenties being stuck on the club diesel the last thing I want to do every time i want to play trains is haul passengers. Really this engine is a stepping stone towards building a climax logging locomotive. Though in reality there may be a few engines built before I tackle the Climax.

[mbrown]

I don't often get to see Model Engineer, so I can't give chapter and verse - but I am almost certain that the ME ran an updated version of "Rainhill", called (I think) "Northumbrian", a few years ago. This would hopefully have sorted out any glitches in LBSC's original design and adapted the design to more modern methods. Worth looking it up, in my opinion....

Malcolm

[robinw]

Yes there was an updated version of Rainhill called Northumbrian that was serialised a few years back. For some reason I prefer LBSC's slightly over scale version. Perhaps I should have a nosey at the updated version too.

[doubletop]

Jun 30, 2015 6:46:09 GMT robinw said:

Yes there was an updated version of Rainhill called Northumbrian that was serialised a few years back. For some reason I prefer LBSC's slightly over scale version. Perhaps I should have a nosey at the updated version too.

Search on this forum for northumbrian and find my thread and peteh's thread

Pete

[robinw]

Jul 1, 2015 19:36:20 GMT doubletop said:

Search on this forum for northumbrian and find my thread and peteh's thread

Pete

I've already had a good read of your build Pete. I think I might have seen your engine sat in the steaming bays at the open weekend at Mariner Park, in Palmy back in 2013.

[doubletop]

Jul 2, 2015 5:01:01 GMT robinw said:

Jul 1, 2015 19:36:20 GMT doubletop said:

Search on this forum for northumbrian and find my thread and peteh's thread

Pete

I've already had a good read of your build Pete. I think I might have seen your engine sat in the steaming bays at the open weekend at Mariner Park, in Palmy back in 2013.

Robin

Which club are you with Parmy or New Plymouth?

Small world, yes the very same, but it was 2014. It didn't get very far that day as I had trouble with the hand pump and with the big boys (7.25") running on the same track they kept holding me up so not wanting to risk a water feed problem I pulled off. It only occurred to me on the way home I could have put a block of wood under the front buffers and kept it running free while I was waiting. I went back again this year and had a more successful run getting in a good few laps in despite the big boys getting in the way again. (for the others the Palmerston North track in NZ is GL, 3.5", 5" and 7.25" all running together. Some of the 7.25" locos are big as they are scaled from 3ft gauge, or less, prototypes)

As others have said, and I'm sure you will realise, Rainhill isn't going to pull you far. I'm sure it is possible to pull somebody and I've seen videos of Canterbury Lamb pulling people, but the trouble wuth Rainhill/Northumbrian there isn’t enough weight on the front to get much traction. However I really should try it again sometime as mine runs freely now and the HVMES track is smooth and very flat.

Good luck with your build.


Pete

P.S. I built mine on a Lorch watchmakers lathe (2.5" center height) until I couldn't stop the chatter doing the small wheels so forked out on a bigger lathe, but by that time I hand made all the other motion parts and the boiler.

[steamcoal]

Pete & Robinw

Good to hear of some small gauge building in New Zealand.

[robinw]

Hi Pete,

I was involved with the Hvmes While I was at university in Wellington approx 1999 - 2002ish Nelson and Palmy prior to that. Currently my step-father is the president of the PN club. It was definitely March 2013, as I currently live in the UK, and that was the last time I was in NZ. Sounds like your Northumbrian runs well, even if its a bit light footed. Being aware of the lack of weight problem I'm planning on building some extra weight into the engine, heavier horns, filling the bottom of the smokebox with lead etc. If nothing else, building Rainhill is allowing me to learn how to use a lathe and mill properly. :-)

Just about have a set of engine and tender beams and pump stay machined up now...

Robin

[gingerneer]

Hi Robin

I run a Canterbury Lamb (similar boiler and cylinders but 0-4-0) yes the pump could be reduce in size, I have been looking at reducing it to 4 mm diameter. Also if possible put the feed water clacks at the front of the boiler, or if they are on the back head fit extention pipes to feed the water in at the front tube plate. For additional adhesion it would be worth fitting steel tyres to the wheels.

Will

[robinw]

Hi Gingerneer,

Thanks for the heads up on the feed pump. I assume the C Lamb's feed pump was originally the same size as Rainhill's at 5/16 x 3/8 (approx 8 x 10mm)?

Thanks too for the observation about the water feed clack. Was going to ask about that in the future when I got that far into the build.

Robin

[gingerneer]

Robin

I will have to double check the loco but I think it's more like 1/4". While she will run on the Bournemouth Model engineers track the length is not a problem it's the gradients. On a flat track she will be quite happy.

Will