|Stewart Hart||18/02/2019 14:13:06|
591 forum posts
I've noticed that most Injectors fitted to smaller gauge loco (5" and Below) are mainly the horizontal type. You can get vertical injectors for larger gauges and for full size locos vertical injectors seem to be widely used.
The possible reason for this is that the ball clack that shuts off with the vacuum, needs a little help from gravity so simply turning a horizontal injector on its side will not work. In larger sized vertical injectors it is possible engineer the clack so that this is not so much a problem, but its not so easy for smaller injectors.
Some time ago myself and a friend started to experimenting with smaller sized injectors our objective was to come up with a simple design for a vertical injector suitable for a 5" loco. After a few false starts we started to understand the issues involved and came up with this design.
On my friends test boiler it worked well, at this point I didn't want to fit it to my loco as I had an injector that was working well, but when its hydraulic certificate ran out and it needing a little maintenance , I decide to fit one of our vertical injectors.
I've now testing the injector on my loco and I'm really pleased how it works it picks up straight away even at low boiler pressure.
I was wondering if any one else has had experience with making vertical injectors for 5" gauge locos.
Edited By Stewart Hart on 18/02/2019 14:48:12
|duncan webster||18/02/2019 20:44:58|
2014 forum posts
Excellent, article in ME?
|Paul Lousick||18/02/2019 21:30:52|
|1043 forum posts|
Duncan, Which magazine edition ?
|duncan webster||19/02/2019 00:38:44|
2014 forum posts
I was suggesting that Stew writes one, then we can all have a go (and get incredibly frustrated!)
|Paul Lousick||19/02/2019 04:32:48|
|1043 forum posts|
Sounds good. I would like to make some.
|Stewart Hart||19/02/2019 07:42:46|
591 forum posts
Thanks for your interest gents
Some people say there is a black art in making injectors:- but all that is really needed is a good understanding of how they work this coupled with some careful machining and patience.
I was given a set of instruction by my friend that I followed and was amazed when the first one worked so made another 4 not one of which worked remade the cones being extra carful and they all worked.
There are plenty of good books out there the best for theory is probably D.A.G Brown's (Miniature Injectors Inside and out ISBN 1857611349) but with all respect to DAG his body design is far too complicated, so to his is method for making the cones. LBSC on the other hand is far to simplified relying on good luck more than anything.
This is the first injector I made
And some of the tools required
As for an article there have been lots of articles in the magazine on making injectors I don't know if the Ed would want any more.
The vertical injector body is made in two parts from hex or square bar and can be made in the lathe with the cross holes drilled the two parts can be silver soldered or soft soldered together. The cones:- which are the critical parts, need carful manufacture to get the critical features correct are made the same as any other injector. Our vertical design uses two over flows the top one (copper Pipe) takes the flow from the combination cones it shuts off when the clack valve closes due to the vacuum that's created, the bottom takes the surplus water from the delivery cone.
I think the main advantage of the vertical design is that you can simplify the pipe runs (less Bends) by moving the water feed onto the best suitable face:- I could have had a straight pipe from the water feed valve into the injector if I'd had its water coupling on the face, facing the valve, but I didn't twig onto this until I had the injector made.
Edited By Stewart Hart on 19/02/2019 07:56:36
|177 forum posts|
Stewart, I for one would love to see an article on your injectors, yes lots of articles have been written about them, but mainly horizontal versions and not many of them work, don’t ask how I know! The only ones I have had success with are D.A.G. Browns, his horizontal ones are superb but his vertical design, although a lovely looking thing is in my opinion complicated to manufacture compared to your design.
|julian atkins||19/02/2019 20:42:35|
1196 forum posts
I have a bit of experience making new steam cones for the Gordon Chiverton vertical injectors so am quite familiar with them.
A vertical injector will work no better than a horizontal injector, and has the disadvantage that the gap in the combining cone cannot be accessed for inspection and cleaning. The Gordon Chiverton design also has the added disadvantage that the delivery cone cannot be removed.
I have never fitted vertical injectors to my own locos.
It is not widely known why Don Young marketed only the vertical Gordon Chiverton injectors for many years. Don Young started his own business around 1971 selling boiler fitting and injectors, and published his vertical injector design for 'County Carlow' in ME in 1970 (which incidentally doesn't work).
He had a gentleman's agreement with Arthur Grimmett, both on the Isle of Wight, that he would not make horizontal injectors that Arthur made in the thousands for Reeves and Kennions.
Don Young via Gordon Chiverton only started making and marketing horizontal injectors after Arthur retired.
As you say, there is a lot more work involved in making a vertical injector (especially of the Gordon Chiverton vertical type), plus I have outlined the disadvantages if they need cleaning or dismantling.
Edited By julian atkins on 19/02/2019 20:44:27
|Stewart Hart||20/02/2019 07:18:14|
591 forum posts
Thanks for your input, I've always found your insight on injectors very useful and informative. That,s a very good point about the combining cones not being accessible, it never occurred to me. I'm planning on using the vertical injector for this years running season so we'll see how it goes.
The horizontal injector I've used for 2 years on my tank engine was the best from the batch of five I made, it seems very tolerant of water temperature I don't need to keep the water on to keep it cool, I must have got the insert depth of the steam cone just right (by luck). Getting the cones in the correct position is probably the most difficult part as most home workshops just don't have the equipment to control and measure the critical features to any great accuracy, I've found the best way round this is to just make a number of different cones and test them and choose the best ones.
The injectors I've made, from DAG Brown's chart would have a delivery rate of about 22-25 oz/min which is a bit on the high side for a 5" loco, they soon drop the boiler pressure, but as I use the axle pump when on the move and only use the injector when stationary I don't find this to inconvenient. The Horwich Crab I'm building won't have an axle pump just two injectors so at some point in the future I'll try and make a couple of lower rated injectors for it.
Edited By Stewart Hart on 20/02/2019 07:23:09
Edited By Stewart Hart on 20/02/2019 07:29:44
|Nigel Graham 2||16/04/2019 21:21:36|
|104 forum posts|
Amplifying a point in re Stewart's original post...
The vertical injectors did seem the norm on most full-size locomotives and many road vehicles, so it surprises me most miniature injectors are horizontal.
The starting-valve in these not only have a little help from that which makes apples fall, but are not ball-valves.
Their various types use instead, flap-valves hinged at the top and separate from the combining-cone, a flap-valve which is also part of the combining-cone wall and also hinged at the top, or a two-part combining-cone with the lower section drawn up to seal against the upper.
The types used on the larger full-size railway locomotives are quite elaborate even in simple mode. The exhaust injector is a very complicated beast!
I once dismantled and cleaned an injector from a two-foot gauge loco, and as I recall its non-return valve was of poppet type.
|Stewart Hart||11/05/2019 17:52:05|
591 forum posts
Please login to post a reply.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.