On Thu, 3 May 2012 16:50:13 -0700, "Bob La Londe"
wrote:

Ok... I'm kind of at a loss here. When I was looking at spindle design,
and lead screw fixed end supports the thing seemed to be to get matched
pairs of angular contact bearings that load up back to back or front to
front when you clamp them together. Basically loads the bearing, end
eliminates endplay until the bearings start to wear. In my ever expanding
often misguided pursuit of knowledge I can't help but notice that there are
nearly as many Double Row ACBs available as single row bearings. Are the
double row just more surface area for greater load carrying capacity or are
they preloaded in a "back to back" type internal configuration to eliminate
endplay in place of two single row ACBs?


As far as I know double row angular contact bearings always have some
internal clearance; in other words, no preload. The most obvious
reason to use a double row bearing instead of 2 single row bearings is
to save space.

I've never seen double row angular bearings in a precision spindle and
off the top of my head can't think of a reason to do so.

--
Ned Simmons