Best piston material for cast iron cylinders

[IanmacParticipant @ianmac]

Another request for some advice.

I'm just about to start to the cylinders of my 7 1/4 Terrier. They are cast iron.

What is the best material to use for the pistons?

Ianmac

[IanmacParticipant @ianmac]

[SpringbokParticipant @springbok]

Well in my mind cast iron with steel piston rings. Do your drawings mention a material.

Bob

[IanmacParticipant @ianmac]

Bob,

the drawings relate to Iron or Gunmetal and I assume the later if a gunmetal casting is used for the cylinder.

I have already been caught out with vague information on this build so am being cautious.

With one eye on when the drawings were produced, some 23 years ago, and what materials are available now, prompted my question. I hear of cases where a combination of cast iron for both piston and cylinder is very rust friendly and siezure can occur if the loco is left dormant for a period.

My motorbike with Cast iron liners in their cylinders use aluminium pistons?

Ianmac

[SpringbokParticipant @springbok]

Hi Ian
If the drawings are that old keep an eye out for errors,missing holes that only apear on a different sheet.

Bob

[Jens Eirik Skogstad 1Participant @jenseirikskogstad1]

Cast iron cylinder —> cast iron piston or aluminium piston + cast iron rings.

Steel cylinder—> cast iron piston or aluminium piston + cast iron rings.

Rare used steel rings in model engines. In large engine with steel rings is often chrome applied on steel against wearing.

[Paul LousickParticipant @paullousick59116]

Some full size engines use aluminium with cast iton rings to reduce the mass of piston.

Car engines have aluminium alloy pistons and cast iron rings.

[61962Participant @61962]

Cast iron cylinder, cast iron piston, cast iron rings. This follows prototype practice and is recommended on model locos. At the end of a run give the cylinders a shot of cylinder oil and you'll have no corrosion problems even after a long lay up.

I also use the combimation of gunmetal pistons and cylinders with iron rings. The rings wear after a lot of running but the cylinders just get polished. One of my 3 1/2 " locos ran five seasons on this combination (probably 2000miles) and was quite steam tight . The rings had about 10 thou wear, but the cylinders were exactly as they were bored.

Aluminium in a steam engine? Not likely. Mixed with water you will get rapid corrosion.

Eddie

[Anonymous]

Posted by 61962 on 03/02/2013 22:40:21:

Aluminium in a steam engine? Not likely. Mixed with water you will get rapid corrosion.

Aluminium pistons are commonly used in model traction engines. I'm planning to use aluminium pistons in my 4" scale compound traction engines, with cast iron rings. I haven't heard of corrosion problems.

Andrew

[NJHParticipant @njh]

Sorry Guys wrong thread! – moved to LSBC thread,

Time for bed methinks!

N

Edited By NJH on 03/02/2013 23:42:22

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