VF1 LS2 140A Mitsubishi alternator, replacement bearings

[Skylarking]

I was wondering what shield (in this case) meant? Wondered if they meant sealed? I've heard sealed for 50 odd years, wondered why all of sudden (just noticed) they call it a shielded bearing?

It’s much of a muchness but I believe shielded bearing had metal shields that didn't contact the inner race and as such had higher speed capability but at the cost of poorer sealing capability that plastic caps would provide.

Plastic capped sealed bearings would contact the inner race and thus their speed rating was lower due to drag/heat of the cap but sealing capability was better.

One can also buy non contact plastic sealed bearings just to add to the confusion…

These days with the amount and type of synthetic plastics, maybe it’s much less of an issue… though one should always look at bearing specs when choosing a replacement.

You’d hope your bearing supplier can help choose the same or better speced bearings than what you removed…