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Re: [TowerTalk] Regarding Worm Gear Drive Winches

To: Mike <noddy1211@sbcglobal.net>
Subject: Re: [TowerTalk] Regarding Worm Gear Drive Winches
From: Dennis Vernacchia <n6ki73@gmail.com>
Date: Mon, 20 Jul 2009 20:35:09 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Yeah I already thought  of that and actually use a 2000 lB rated come along
as I don't happen to have a few hundred pounds of weight around

and also I wonder how much weight the tilt structure
is rated for and don't want t overload and crumple the tilt fixture !!!

73, Dennis N6KI

On Mon, Jul 20, 2009 at 8:26 PM, Mike <noddy1211@sbcglobal.net> wrote:

> 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@contesting.com
> [mailto:towertalk-bounces@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@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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