[tag corrected]

> I'm thinking that using an old battery-powered drill used as the=20
> motor and gear-box might be an inexpensive and reliable=20
> solution

That's a good something to try. I used one as an automatic curtain
opener (winding and unwinding the draw string) and they certainly
do have a surprising amount of torque

As the arm is balanced it should be fairly easy to move. The barriers
at car packs can use quite a small motor as the counterweight does
a lot of the work. This is also true of bascule bridges, clocks, steam
train wheels and elevators (lifts)

The only slight concern, as it's outside, might be the effect of wind.
Perhaps a magnet at one end to hold it to a pole

Joe




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