On 7/22/23 2:33 PM, Richard (Rick) Karlquist wrote:
On 7/22/2023 10:08 AM, Lux, Jim wrote:
I wonder if there might be a case for a major design approach change
for rotators.
I have an HDX-5106 tower where the top section is only 15
inches wide. Only the small prop pitch, and the Orion rotator, and
the upcoming DXE rotator, will fit into my tower, while
having even a prayer of turning my MonstIR. Smaller rotors that
will fit into Rohn 25 don't have the power. There are larger
really heavy duty rotators that don't fit my tower, while also
allowing it to crank down. They all have the motor sticking out
which only works for a fixed tower.
Does your paradigm fit into towers like mine?
I would think so - a standard 56 frame motor is 5 -5/8" (5.625") in
diameter (approximately) and about 9" long (without the shaft).
I've seen both inline and right angle gear boxes.
The critical dimension is the clearance between the vertical tubes.
Would someone want to install this inside Rohn25? the center to center
of the tubes is 11" 1/4" and the "tube to side" is 9 3/4" so I think it
would fit.
Inline gearboxes are almost always the same diameter as the motor frame.
I think, though, you'd need to stack two gearboxes to get the ratio big
enough (e.g. a pair of 20:1 would give you 400:1, 4 RPM max output speed.)
The trick would be finding "off the shelf" units that are inexpensive
(you can buy a 56 frame 400:1 planetary reduction assembly, but it's
probably $5000, at which point the motor is essentially free)
Worm gear boxes tend to be right angle
https://www.automationdirect.com/adc/shopping/catalog/power_transmission_(mechanical)/worm_gearboxes/aluminum_worm_gearboxes/wga-63m-100-h1
or dimensions:
https://cdn.automationdirect.com/static/specs/wormgearspecs-al.pdf
I think if you went the worm gear route, the motor would be horizontal
and sticking out the side of the tower.
There's definitely some bracket fabrication involved - it's not going to
be something you bolt together from parts from the local hardware store
or order from Amazon. But these days, getting plates drilled and cut is
a mail order thing. Welding is probably a "go find a shop".
25 years ago when I was doing a lot of this kind of thing, I was
surprised how much of this power transmission stuff is inexpensive and
"get it tomorrow from Grainger" kind of stuff.
BTW, an interesting idea would be to use a small hydraulic motor at the
top, and a pump at the bottom. Drive the pump with a reversible motor.
You'd have to rig hoses or tubing up and down, and it's guaranteed to
leak a little, but the motor (and pump) are tiny. This is a low
performance application, so hoses would be fairly inexpensive ($1-2/ft)
because you don't need a big honkin' 3/4 ID. I'd have to find my
hydraulic system calculator, but this is one of those "could be really
lossy and still work" systems.
At least there's no wires to the rotator, so lightning might not be a
big issue.
Running a hydraulic motor at 1 RPM is easy.
I'm not sure, though, whether you've saved yourself one hassle
(custom/surplus motors and such) and gained another (hydraulic fluid
maintenance). The sealed motor and gearbox thing is literally a "don't
touch it for 20 years" kind of solution.
73
Rick N6RK
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