On 5/22/20 9:29 AM, Stan Stockton wrote:
I have an extra large prop pitch that has been turning a large 40m Yagi for
13.5 years. Unfortunately the gear reduction on the extra large prop pitch is
only 5830-1 instead of 9576-1 for the small one. I am guessing the small prop
pitch would hold it. At any rate, although it does a fine job of turning the
antenna, and would hold most any antenna you could imagine, the prop pitch has
never been able to hold this antenna in place. I've probably replaced the coax
jumper between the hardline at the top of the tower and the hardline on the
boom a dozen times after big winds.
I know that mounting the prop pitch outside the tower with the proper gears and
chain I could make it hold the antenna. What I would prefer is to install a
brake of some kind that would stop the shaft coming out of the bottom of the
motor to keep it from turning. I would think the torque would be small. I
haven't tried it but want to think I might hold that antenna in place with my
fingers on the shaft coming out the bottom of the motor??
Anyway, the question is this. Does anyone have an idea for an off the shelf product that
could be adapted to stop that shaft when I wanted to "park" the antenna or
after it is rotated with a delay?
Grainger (and most industrial suppliers) have electric brakes which
connect with standard industrial motor shafts. They come in two flavors
- power to apply and power to release. There's some pretty small ones
in the catalog.
There are also things more akin to the parking brake in a automatic
transmission - a cogged rotor with a spring loaded pawl that can be
pulled out of engagement. That's more of a low speed, high torque
If you want a "modify something" adventure, most of the small AC powered
shop winches have some sort of brake scheme to hold the spool when not
extending or retracting.
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