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RE: [APD] Eheim shafts -- or - Bearing the Ehiem Design



Ceramic is more fraigle than steel, but it wears very well.
Eheim's have used ceramic shafts for years and years and
years and years -- well, you get the idea. Other pump
makers have since copied the design.

I did break a ceramic shaft once -- I stepped on it. No,
not on purpose. But they have very little tensile strength;
if you try to bend, on purpose or not, it will break.

Speaking of water pump shafts, Here's a first impresson on
the new Pentair pumps. I had a chance to see one of the new
line of pumps sold under the venerable name of QuietOne.
These use a stainless steel shaft that is fixed on one end
to the stator inside the cavity for the rotor. The rotor
fits over the shaft, held in place only by the magnetic
field and centered by the shaft. So one won't be replacing
bearings in this pump ;-)  The Eheim, uses a rubber bearing
(or "bushing" might be more accurate) on each end of the
shaft to hold the shaft in place and thereby keep the rotor
centered. The QuietOne design has one less part than the
Eheim design -- there's a certain elegance in that :-) 

They're too new to know if they are as reliable as the pump
that formerly sold under the Rainbow Lifegard QuietOne
name. But they are epoxy filled instead of water cooled --
so there's no seal to give out. They can be run in and out
of water but the smaller ones don't have intake hook-ups
for non-submersed use.


Scott H.
--- "Gegner, Eric" <egegner at mpcproducts_com> wrote:
> The Eheim has a ceramic shaft which is very fragile. A
> weak link.


=====
S. Hieber

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