I wonder if there might be a case for a major design approach change for
rotators.
As noted in the recent thread, prop pitch rotators are getting rarer.
A similar phenomenon occurred with horse hot walkers - they used to be
made from the rear end of a vehicle, a standard transmission set into
first or reverse, (both from a junk yard) and a belt drive from an
induction motor to the transmission. But over the years, cheap surplus
transmissions and rear ends have become more rare. So now it's an off
the shelf right angle drive and induction motor and controller.
These days variable speed drives for 3 phase induction motors are pretty
inexpensive ($150 for a single phase input, 1/2HP). One can get a
small, TENV motor for about $500 (washdown, 1/2 HP, Leeson). You'd
need a gearbox, which is probably another $500 to get from 1800 RPM down
to 18 RPM (and you'd just run the motor slower, because what you want is
something like 1 RPM) I've not gone through the catalogs, but 100:1 is a
standard ratio.
You'd probably want some sort of slip clutch to limit the torque loads
(or not, if the gearbox can be back driven or is "strong enough").
But you could do this all with off-the-shelf commodity components that
are specified for use in the appropriate environments. The value added
in a product would be the bracketry, and the kitting. (I.e. Sure you
could cobble your own together, but it's easier to just pay $4000 and
get a box delivered to you).
3 phase induction motors are nearly indestructible, and if you DO need
to repair/replace it, they're standardized and there's a hundreds of
motor shops to do it.
Weather seals for such items are standard items.
Probably the big issue might be that the motors are 208-240V, but you're
running at low speed, so running it off 1/2 voltage is probably viable.
Or find a 120V single phase PSC in the right package that your
controller can start.
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