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Machined components are a critical difference
Another
factor affecting alignment is proper fit of component parts such as
the shaft, bearings, bearing mounting, and pulley. Some fan manufacturers
Purchase and assemble these parts without providing for a machined
fit. This can greatly increase bearing load due to imperfect alignment,
or worse, components may shift and cause binding between parts. These
problems can be avoided with machined and fitted components,
as used in American Coolair Type JBH/JBHX Upblast and Type PBH Hooded
Power Roof Ventilators, as well as CBL/H/X wall fans.
How
blade assembly design affects fan life
The blade assembly is one
of the hardest- working pans of a Fan or PRV. This assembly is subjected
to conditions that encourage vibration and in turn can reduce fan
life.
When blades are mounted on spider type arms, support is minimal
and vibration problems can increase. For this reason American Coolair
hubs incorporate a circular support that increases blade
assembly rigidity by a factor of at least two.
The
difference is a factor of at least two
Blade alignment and blade
rigidity also affect the potential for vibration. For this reason,
bolted blades of heavy gauge are the most reliable. Welded
blades are difficult to align properly, and riveted blades lack
strength.
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