Double Row VS Dual Single Row Angular Contact Bearings

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?

Reply to
Bob La Londe
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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.

Reply to
Ned Simmons

Ok. That's pretty much what I wanted to know. They are NOT the equivalent of two single row bearings back to back. Thank you.

Reply to
Bob La Londe

IIRC they are beginning to see quite a bit of use these days for high = end circular saw arbors and the like--two sets are installed and = bellevilles are used to slightly load them in a direction opposite from = each other.

Really no reason the same thing couldn't be done in milling arbor--the = advantage being ease of manufacture and assembly....attaining zero = clearance becomes almost a no-brainer at the assembly stage even if = dimensionionial tolerancing is relatively loosely held for the shaft and = housing lengths.

Reply to
PrecisionmachinisT

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