Pistons for Emma Victoria

Will soon have the cylinders finished and my thoughts turning to the pistons.

I've chopped the cylinders out of a solid iron tractor weight that a farmer gave to me.

In the series in M.E. packing and O rings are shown as 2 methods, in detail for bronze running in bronze but no details of iron running in iron other than the suggestion of using iron rings.

I have in the past successfully made iron rings for small i/c engines so I'm not worried about actually making them.

The pistons are 1 1/4" d x 1/2" thick.

Is there any advantage to having 2 rings in each piston or will 1 be ok ??

Hope someone can advise please .. John

Two allows thering joints to be staggered so less blow past.

Hello John

You are correct, in my write up I just mentioned if the builder prefers to use cast iron for the cylinders, then I suggested the use of cast iron rings. I used cast iron on my simplex which has been and still is running since 1976 on my home made cast iron rings with no loss of performance. I put two rings on the piston and made them 1/16"thk. x 3/32" wide and staggered the gaps as pointed out by Jason B to help prevent blow past. Whether having two rings is better than one apart from the blow past as mentioned and having one extra in case one should break, then I would not like to say. Again, I point out the need for an oiling point on the steam chest for giving a dose of oil after running is finished to prevent rusting. I hope this is of help to you.

Cheers Henry

Many thanks to you both, that's killed a pig .. John

Cast iron on cast iron is the best bearing surface. I had not seen it until I rebuilt a Stuart Turner S9 steam engine, this engine has a 1 1/2" dia piston 3/8" deep, with a 1/4" ring groove, in that I put 2 x 1/8" wide cast iron rings, when fitted the gaps were staggered 180*.

Ian S C

Ian, did you put 2 rings in 1 groove only because it was a narrow piston or is there any other advantage?

JK - If you struggle to make the rings or to fit them without them braking you could do a lot worse than use packing instead. Its available ont tebay for little money and it is so much easier. I was very wary of this method until I tried it for myself, excellent results!

The engine was a rebuild, and the piston had been made with the 1/4" wide groove, is seems Stuart Turner used the method, and it works ok, and in a piston 3/8" wide there is little room for two 1/8" grooves. I did some repair work on a ST Progress vertical slide valve engine, it to had a single groove, but I packed that with Teflon plumbers tape. I could have made and fitted two cast iron rings, but the cylinder on that little (1/2" bore), is bronze.

Ian S C