ST Heads in the Pacific NW

[hotater]

Doug---

Aluminimum housings have a different rate of thermal expansion so the bearings loosen as they get warm.  That's why radial thrust ball bearings are usually used with aluminum housings.  Use a thrust spring under any bearing in aluminmum and it'll last longer.

[Doug]

I do remember those thrust springs, used mostly on smaller motors. Asea used to have a complicated set of shims and spring washers in their larger alum frame motors. Others used steel inserts in the end bells but the small cheap stuff didn't and thats why they never did last.

Its been a long time since I did any work inthe motor shops.
I don't miss it.....

Doug