DRSkruffy@aol.com wrote:
>
> They have to use a 3450 RPM motor
> to advertise a 5 hp motor.
Speed has nothing to do with power output. It's just more expensive to
build a 1725 than a 3450 for the same power level.
> From what I recall, the 5 hp 3450s are drawing
> like 15 amps, but the 1725s are drawing 30 or more.
That's because the "5hp 3450s" aren't 5hp motors at all. What they do
to lie with ratings is put a big flywheel on the compressor, and then
calculate the peak instantaneous power delivered from the flywheel to
the compressor.
> Also, if you notice the
> shaft size on the 3450 RPM "5hp" motors, it is about half the size of the
> 1725s.
Since power is torque times speed, a 1740 motor has to make more torque
for the same power output, hence needs a bigger shaft. The other thing
is that again, the 3450s are "el cheapo" and use a smaller shaft because
it's cheaper.
> I spent a lot of time on this last summer. When my Sanborn piece of crap
> threw a rod I thought I could just put a better pump on the tank. Simple huh?
> Well, I could have replaced it with something similar but everybody I asked
> said I could not put a 5hp Quincy pump on it because the motor wouldn't pull
> it the way it was supposed to.
It's amazing what you can do with a few pulley changes. The slower you
turn the pump, the less power it takes to turn it.
Randall
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