[TowerTalk] Fwd: Fwd: FW: Fwd: Worm Gears

[Richard (Rick) Karlquist]

On 7/16/2015 7:12 AM, David Robbins wrote:
>
> doesn't it get even uglier than that?  at 50% if you stop the worm gear it would stay put, but if it gets bumped and starts moving the friction needed to stop it is more than the friction needed to keep it from starting under a constant load.  So while 50% might be the break point, you actually need it lower to make it self breaking, low enough to overcome the sliding friction when it is running to bring it to a stop.
>
> Jul 16, 2015 10:04:41 AM, hanslg at aol.com wrote:
>
> Kelly,
>

Exactly right.  There is a difference between static friction
(referred to as "stiction") and dynamic friction.
When I had my KW3000 winch, and the tower was near
vertical so there was only a moderate load on the winch,
I could spin the handle to let the tower go down.  The
handle might go around 5 or 10 times with one shove.
So the winch was barely self braking under those conditions.

Rick N6RK