[TowerTalk] Prop pitch question

[jimlux]

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.