Harold_V wrote: ↑Sun Mar 12, 2023 4:48 pmRings in a steam engine should NOT attempt to center the piston. [snip] rings should have enough clearance at the root diameter that they can NOT influence the piston. H
Re: my question . . I learned yesterday that it doesn't matter greatly if the ring can be pressed below the surface of the piston as long as there is depth clearance in the groove, and that clears a few things up.
In a conversation with an experienced builder in the UK, he learned years ago that properly fitted metal rings, of the type I have, used with adequate clearances, whether intended or not, will tend to center the piston by simply working the way they're designed. To escape confinement (or expand - however you want to state it) on the power stroke the steam will find its way into the ring groove where it will exert equalized pressure under the ring, expanding it against the bore, thus acting to help center the piston. His experiences, and what I saw in the Mfg's notes, were that side clearance is tightly specified, but groove clearance no so much (although within reason.)
No, of course this effect should never be expected to compensate for wear, mechanical defect, or poor workmanship. That goes without saying, usually.