Garden Railway Forum

Billy's right I fear... It's all very well making it look pretty, but unless you want it to grace the mantlepiece and not the railway, I'd be more concerned with making it work.

If you want two cylinders then increase the capacity of the boiler, thus meaning more steam is available and also a longer running time due to the higher water capacity.

You could always fit a dummy second cylinder for aesthetic purposes if it really bothers you- so long as there's next to no compression in it it shouldn't provide too much extra load. Of course you could initially fit it as working and if it proves too much for the boiler remove the steam lines to it and maybe fit smaller 'o' rings or something to the piston so it's a loose fit in the cylinder.

If you want this to work you'd do well to take the very sensible advice of some of the other posters instead of arguing with them- they aren't telling you it wont work out of spite or to be awkward, they are telling you it won't 'cos chances are- it wont!

if a gas burner, even meths burner, can make enough steam for a mamod, then surely it must be able to make enough steam for two mamod cylinders for my loco

andysleigh wrote:if a gas burner, even meths burner, can make enough steam for a mamod, then surely it must be able to make enough steam for two mamod cylinders for my loco

I think the problem is that on the Mamod loco, it has a much more efficient combustion chamber that directs the heat around the boiler, the heat spreads all around the bottom of the boiler and around the sides. On a vertical boiler there is much less area for the heat to transfer to the water, also much of the heat will just draw straight up the chimney and be lost.

Also as the loco is going to be geared down, the cylinders will be running faster than on a direct drive loco so the steam requirement will be higher. I think that single acting cylinders could work quite well, but just using a Gas burner. At the end of the day it's your project and it's clearly been done before as you are working from the article in SMT!

I'd go ahead with 2, and see what happens. If it isnt successful, at least you could remove the pipes to one of them and the connecting rod.

Hi Andy
As suggested before below is my suggestion for gear ratios for 1 or 2
cylinders.
If you use a more or less copy of my boiler as in SMT it will support 2
Mamod type cylinders if you gear between 2 and 2.5 to 1 reduction. This will
give about the same number of power strokes for a given loco speed. To
calculate, 1 rev of loco wheels X gear ratio X 2 power strokes for each
cylinder.
1 X 5 X 2 = 10 for single cylinder
1 X 2.5 X 4 = 10 for 2 cylinders.
So the steam consumption at a given track speed will be the same. Note that
a 2 cylinder loco will happily run with a much lower cylinder speed than a
single cylinder.

Regards
Allen Morgan
W.E.Lt.R.

And now you can see that it was right to question it, it wouldn't have worked properly otherwise.

indeed

I dont understand why nobody makes an engine like this commercially

Id buy 1! probably be a good price to

Any progress Andy?

nope,
I am waiting till the Alexandra Palace model eng show in mid january to buy materials