> I have a Dadant 10/20 Stainless Steel radial extractor.  The bottom
> bearings on the main shaft usually burn out every third year, right in
> the middle of extracting.

I wonder if pressure washing could be part of the problem?
http://www.honeybeeworld.com/diary/incl/DSCF4598.JPG

Pressure washers are able to easily and accidentally push water past 
seals and into otherwise waterproof parts.

It is important to keep both water and honey from entering a bearing. 
If water sits in a bearing for long, it will rust and pit, then become 
noisy and fail after a few hours of service.  Even a little honey will 
cause it to heat and bind.

Bearing types designed for radial loads may have some thrust rating, and 
_can_ sometimes be used for an application with thrust, but doing so is 
risky design and likely to result in a short service life.  Best to use 
a bearing type intended for thrust in a thrust application.

The bottom extractor bearing is subjected to both trust and radial loads 
(unbalance can generate significant radial loads), so the bearing 
selected should be adequately rated for both types of loads.  The top 
bearing load is principally radial, although there is always a trust 
component due to flex if it is locked to the shaft, as it should be.

Also it is easy to forget that the same bearing number from different 
sources can differ significantly in noise level and also service life. 
(I covered this before under a Dakota Gunness discussion, pointing out 
that the original bearings were very noisy, but German replacements were 
silky quiet).

Price is an indicator, but sometimes a cheaper bearing is better for an 
application.  A good bearing supply shop can advise.

That said, I borrowed one of these extractors one time and I seem to 
recall that they are not designed for more than very light and 
occasional use and that the construction is very lightweight and basic.

I also seem to recall that the bottom bearing supplied did not appear to 
be a real thrust-rated bearing, but one designed for principally radial 
loads.

It is possible to use a light-duty extractor in heavy service, but 
problems are probable as usage hours accumulate. I used a 4-frame 
reversible to extract 100 hives when I started out, but it was built 
back before engineering had advanced to the point where manufacturers 
felt confident enough to scrimp on material.  It was heavier than a 
modern 10 or 20-frame unit.

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html

Guidelines for posting to BEE-L can be found at:
http://honeybeeworld.com/bee-l/guidelines.htm