Jim Hargrave wrote:
> >Although I saw some one say they run at
> >several thousand RPM my guess
> >would be closer to 680 to 800.
> >The easy was it to count the
> >number of
> >poles and do the math.
>
> Roger,
>
> I was the one that made that statement. My reference was to the Prop Pitch
> drive motor, not the Tailtwister. Apples and oranges. Following is the
> reference:
>
Ok, I read it as the Tailtwister.
> >I am getting ready to "retire" an overloaded Tailtwister
> >rotator with a "small" prop pitch motor (9,576:1 reduction
> >ratio) and was wondering about a couple of details in
> >regards to putting it in service.
>
> Now lets do the math. If the output shaft turns @ 1 RPM, then I submit that
> the motor better be turning @ 9,576 RPM. Bear in mind this is a series DC
> motor and basically the rpm is limited by inertia and friction, including
> the target load.
>
True about rpm limiting and the RPM for the prop pitch motor. I can
understand why they went to hydraulics <:-)) Theoretically one without a
load would be capable of an infinite RPM, but they have very little
torque. An unloaded series motor with little friction will run extremely
fast, Given very little resistance they have to be built fairly sturdy
so as to not fly apart. The rotator I had apart did not run fast at all
and the motor could easily be stopped by sticking a pencil eraser
against the rotator. I think die grinders would likely be series wound
as they run up to 30 or 40,000 RPM.
73
Roger (K8RI)
>
>
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