[TowerTalk] Tower winch failure

[Al Williams]

I have been hoping that a knowledgeable towertalkian would offer a posting 
on how brake winches work but again nobody has.
I am not a mechanical or civil engineer and know little about winches, 
however I can make observations and these are what follows:

About a year ago I was jacking up one side of my LM470 electric winch tower 
in preparation for tilting it down.  When the center of gravity moved enough 
the winch handle started revolving and the tower was falling over on its 
own.  The handle was moving slowly, but definitely picking up speed.  I 
grabbed the handle and stopped the tower from continuing to fall.

I do not know what the conditions were that allowed this to happen. 
However, I have since tilted the tower up and down several times with no 
problems but I am very careful to test that the braking mechanism is 
engaged.

Actually I have two k2550 and one k1550 winch and all three were purchased 
from separate sources with months between the purchases.  All three have 
what I call a "free wheeling" mode and operate similarly.  When the tower is 
being tilted up and becomes near vertical the center of gravity takes over 
and the tower will fall into vertical place releasing the tension on the 
tilting cable.  If the winch handle cranking is continued to take the slack 
out of the cable the tension becomes taut and the winch cannot be cranked 
tighter.  Now, if the winch handle cranking is reversed (like trying to tilt 
the tower back down) but the tower center of gravity has not changed i.e. no 
effort has been made to actually tilt the tower, the handle requires a 
substantial pull to free it to turn and then become easier to turn and 
eventually the weight of the handle alone is enough to turn the winch drum. 
Remember the tower has not moved, all that has happened is that the cable 
has gone slack. (Not quite true I think-- the braking mechanism has also 
been disengaged)

I make the assumption that the braking mechanism has been relaxed or even 
almost removed.  The braking mechanism appears not to be engaged until the 
cable is subsequently made to become taut again by taking the slack out of 
cable and tightening firmly.

When the tower is being tilted down; the braking mechanism is working 
properly and the tower comes to rest on the ground, if the winching 
continues  until the cable tension is removed and the cable becomes slack, 
the braking mechanism appears to release just as I reported above.  The 
winch becomes "free wheeling" but since the tower is on the ground no harm 
can result.

When my near accident of the tower falling occurred, I continued cranking it 
down by keeping hold of the handle.  I suspect that if I had reversed 
direction to crank the tower back up that the braking mechanism would have 
"snapped" into operation.  I don't intend to experiment to confirm my 
suspicion.

Joe may be correct in that "...the winches are not designed or intended to 
freewheel".  However the anomaly seems to be in the design and use and not 
in my particular units.  Users of Fulton k1550 and k2550 braking winches 
should be aware that these winches  can get into a "free wheel" mode without 
a winch failure.   It would be easy to confirm this and I hope that someone 
will and report it.

k7puc





----- Original Message ----- 
From: "Joe Giacobello" <k2xx at swva.net>
To: "Dino Darling" <dino at k6rix.com>
Cc: "Al Williams" <alwilliams at olywa.net>; <towertalk at contesting.com>
Sent: Saturday, March 17, 2007 11:55 AM
Subject: Re: [TowerTalk] Tower winch failure


> That's good to know.  I have never seen the free wheeling problem here.
>
> 73, Joe
>
> Dino Darling wrote:
>> The K series winches are not designed or intended to freewheel.  This
>> is not a feature, but an anomaly.
>>
>>> I'm using 2550s on LM-470s here too and wasn't aware of the
>>> free-wheeling mode.  I'd appreciate hearing the details too.
>>
>> Dino - K6RIX
>> dino at k6rix.com
>>
>
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