[TowerTalk] Belt Slippage on LM-470 Towers

k0dan k0dan at comcast.net
Wed Nov 23 14:06:55 EST 2005


Interesting. I'm gonna send a photo to your email address, would like to see
if you can steer me to what you mean by "hub of the driven pulley is a
clutch". I either have no clutch, or it is corroded into non-existence, or
maybe tightened beyond functionality.

I -have- snapped a cable before....under unusual circumstances (excess slack
caused pull-up or pull-down cable (I forget which) to slip of the pulley on
the top tower section, it got pinched and the motor had enough torque to
snap it). Not sure a clutch would have helped, but might have added a little
extra margin (or noise) to warn me before the failure.
As it is now, the motor starts, there is no clutch slippage, maybe the belt
slips a tad but this is not apparent, and the tower instantly begins to go
up or down. No big problem. But a little extra "momentum buffering" would
probably be a good idea.

I have replaced the tower motor twice before (Leeson makes a fairly
inexpensive "washdown motor" which is right size, HP, and bolt pattern for
the LM470 application), however I think you are referring to the clutch
being in the gearbox which is kind of a mystery and certainly a bigger
production to replace than the electric motor.

There is also an odd flange with unexplained bolts on the shaft of the
pulley which comes oout of the gearbox. I think this is what you're
referring to as "clutch" but I want to send you a phot (picture is worth
1000 words).

Thanks and 73


----- Original Message -----
From: <paul at w8aef.com>
To: "Tower Talk" <TOWERTALK at contesting.com>; "k0dan" <k0dan at comcast.net>
Sent: Wednesday, November 23, 2005 11:56 AM
Subject: Re: [TowerTalk] Belt Slippage on LM-470 Towers

> The hub of the driven pulley is a clutch.  This is true on my LM-470 and
> true on my HZN-354.  (Not true on my Tristao TX-455).
> What I call the driven pulley hub is mounted on the keyed worm gear the
> drive shaft and the pulley fits over the tapered hub with a plate and 2
> bolts that secure the pulley to the hub.
> It's been a long time since I made this adjustment on my HZN-354 but I
> recall I inserted a two by four through the lowered tower (so it would not
> destroy itself if the cable broke), removed the drive belt, loosened the
> bolts until the pulley turned freely on the hub, then tightened the two
> bolts until I could still move the tower up and down by turning the pulley
> by hand (no motor) but when the tower was against the stop (2x4) the
> would slip.
> There is no procedure for this in the manual.  It's the procedure I used
> because when I obtained my HZN-354 tower (used) the driven pulley was not
> the hub.
> The ususal weasel clause(s) apply in this case.  Just as the manufacture
> not responsible so am I not responsible for any misfortune you may suffer
> you or anyone else by following what I did.
> de Paul, W8AEF
> ----- Original Message -----
> From: "k0dan" <k0dan at comcast.net>
> To: <paul at w8aef.com>
> Sent: Wednesday, November 23, 2005 6:34 AM
> Subject: Re: [TowerTalk] Belt Slippage on LM-470 Towers
> > What clutch? What clutch adjustment?
> >
> > The "optional" (but should be "mandatory") limit switches should shut
> > motor off just before max up & down positions.
> >
> > I have never been aware of any clutch action on my motor or gearbox, nor
> > is
> > it mentioned in the manual.
> >
> > 73
> >
> > Dan
> > K0DAN

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