The Steamboating Forum

Here's a cool and detailed site by a guy who built his own small compound:

http://aldunlop.com/Dunlop1.375X2.5X1.7 ... ction.html

That's a nice engine and some interesting machining techniques.
I note that Al is using aluminium pistons. This will keep the reciprocating weight down, but somehow I had a notion that iron should be used with steam. Anyone? John

Johnlanark wrote:That's a nice engine and some interesting machining techniques.
I note that Al is using aluminium pistons. This will keep the reciprocating weight down, but somehow I had a notion that iron should be used with steam. Anyone? John

Aluminum works fine for steam engine pistons at traditional pressures and temperatures. Those running 1000F superheated steam need not apply....
One does need to consider the 3x larger thermal expansion rate of aluminum.

- Bart

I can't see any problem with aluminium pistons in the engines we use. Its only when aluminium overheats that it causes problems, and it will only overheat if the friction is too great.

The piston rings should be the only thing touching the pistons anyway, and they shouldn't move much on the piston.

I run aluminum pistons on my compound at up to 165 with no issues thus far....saturated only.

Dave

if you were worried about wear in the ring lands or elsewhere on an aluminum piston (
as well as corrosion), you could always have them type 3 hardcoat anodized.