On 17/01/2020 02:47, Bill Wright wrote:
I was trying to think of all the sacrificial things. Sacrificial anodes
on ships, yes. But... how about the face of a wooden mallet? Because the
reason it's wood is because steel would be too hard. Because the wood is
softer it's more likely to get damaged. Stretching a point? A wooden
gramophone needle, which wears out quickly but doesn't damage the
shellac? Can anyone think of sacrificial things?

Bill

Not quite sacrificial but white metal bearing linings are used for two
reasons, firstly they melt without damaging the shaft if they lose the
oil supply, secondly large abrasive particulate in the oil embeds deeply
enough *not* to make it become a lap.

Tip: this does not apply to bronze bushes running (lubricated) on
hardened steel shafts. A colleague once thought it might be a good idea
to polish some car internals with (snaffled) diamond paste. Evidently he
did not clean it sufficiently well, because there was enough in the
system to turn the bronze camshaft bushes into laps, which wore out the
camshaft bearing sites in a few thousand miles.