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Re: [TowerTalk] Regarding Worm Gear Drive Winches

To: "'Dennis Vernacchia'" <n6ki73@gmail.com>
Subject: Re: [TowerTalk] Regarding Worm Gear Drive Winches
From: "Mike" <noddy1211@sbcglobal.net>
Date: Mon, 20 Jul 2009 21:12:13 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
No problems for the tilt over fixture, it will easily handle the extra 150 -
200 pounds, make sure you grease the pivot bolts on the fixture.  

 

I don't know if you are using the original winch mounting plate and hole
pattern with your KW3000 Worm Gear Style Winch, but I noticed that the
design in not correct for the standard K-2550 winch when tilting at the 8
foot level because the bolts hole are at the bottom of the winch, this is
fine when you are cranking the tower up from ground level using the top
pulley on the tilt over fixture.  It is not fine when you are using the
bottom pulley to tilt over the tower at the 8 foot level to load the
antennas on.  This is because the cable now runs out on the other side of
the drum to the lower pulley and if you have a 15 foot mast with 80 pounds
of antenna on it you will peel the winch of the mounting plate.  Because the
winch cable must lead out off the drum with a near vertical pull it needs to
turn around and bolts and hole added to the top side of the mounting plate
to stop the load from pulling the winch from the plate.

 

This is hard to explain, but if you run the cable routing through your mind,
you will understand what I mean.  I almost had a nasty mishap here before I
realized what was going on and had to attach a couple of emergency C-Clamps
to the top of the winch and mounting plate to stop the winch from pulling
off the mounting plate to save the day.

 

Mike, K6BR

 

From: Dennis Vernacchia [mailto:n6ki73@gmail.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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>
>
>
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