On Wed, 15 Feb 2006 14:30:32 -0000, (Chris
Lewis) wrote:

According to Jeff :
Are you sure the engine didn't use
Babbitt bearings
(http://www.americanbabbittinc.com/hi...t_bearings.htm) which
looks similar to aluminum?

It's exceedingly unlikely to see babbitt metal in any small equipment like
this. Small engines either have ball bearing or bearing bronze sleeves.

Their normal operating temperatures are too close to babbitt's melting point,
and it'd wear too fast at the high RPMs these motors generate.

Babbitt metal use is largely limited to _very_ large open bearings on
large and old equipment. Eg: very old and large scale machine tools like
industrial lathes of a few decades ago, large scale shafting (eg: ship
driveshafts), steam engines and the like.

Or small bearings like in Ford Model T and A's and many many older
automotive engines that did not have insert bearings.


You can usually tell a bearing is babbitt, because the housing is designed
so that you can pour molten babbitt into it, and sometimes even remelt the
babbitt. Babbitt bearings are cast in place and are usually quite large
beasties with oil cups etc. As the babbitt wears, you need to periodically
remelt it to reduce bearing slop.

In small engines, babbit bearings are not poured "to size". The
babbit is bored to size after it's been placed. Usually, after the
babbit is poured and before boring it to size a thick shim pack is
installed and as wear progresses, shims are removed.

http://users.michiana.org/rosss/modela.html


It's cool stuff, but most people are unlikely to ever encounter it these
days, except in antique steam engines at museums and country fairs.

Or in those other places I mentioned above.