[TowerTalk] Regarding Worm Gear Drive Winches

[Mike]

Do yourself a favor when you tilt the 470 over or lift it up with a mast and
antennas on it, attached a couple of hundred pounds of weight on the base
end to counter balance, you will find the whole procedure goes way much
easier.  This only applies with the LM-470 when you tilt over at the 8 foot
height using the tilt over fixture of course. 

Mike, K6BR

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Dennis 

Just picked up a NEW Fulton KW3000 Worm Gear Style Winch today which I plan
to use with a 1/2 inch variable or low speed Drill  motor to tilt a
LM-470D tower that has around 1300 lBs dead weight on the cable when
tilting.

Anyone have any bad experience with this particular winch ?

Will it hold under load or tend to creep. I don't intend to not lock down
the
handle but good be good to know any anomalies with this setup


BTW they are on sale right now at Grainger for $143.( while supply lasts
whatever that means )

73, Dennis N6KI

On Mon, Jul 20, 2009 at 12:27 PM, Dan Zimmerman N3OX <n3ox at n3ox.net> wrote:

> >
> > Depends on the particular worm gears (more specifically, the pitch of
> > the worm).  It's like whether you can backdrive a lead screw. Sometimes
> > you can, sometimes you can't.  The finer the pitch (= higher numerical
> > gear ratio) the more likely you can't backdrive.
> >
>
> You have to be a little careful too, even if it "appears" to be self
> locking.
>
> The mechanism that disallows back-driving is ultimately that the static
> friction becomes stronger and stronger under load when you try to
> backdrive,
> "locking" the thing in place.
>
> But if you have some vibration and a moderate load, just like any other
> frictional pinning, it might creep.
>
> And if it gets going, then you aren't looking at a static friction
> situation
> anymore, and it might not be *dynamically* self locking.
>
>  And as N2JFS says, it might be easier to backdrive over time.
>
> So I'd say don't rely on it.  And that's what worm gear drive
manufacturers
> would say: don't rely on a self locking worm drive in place of a proper
> braking system in an application where it may be dangerous if it slips.
>
> 73
> Dan
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