I'll try to add a little extra clarification (mostly from memory) about the
friction clutch: On the input shaft (that's the one with the crank handle)
there's a threaded section where one of the clutch parts is assembled. I
can't remember whether it's the friction disk or the pressure plate, and
it's not evident until you disassemble the thing. This threaded interface
causes the friction parts to be pressed MORE tightly together when the CABLE
is applying a load to the shaft. When the CRANK is applying a "pay-out"
motion, the clutch pressure is REDUCED...just enough to allow the drum to
move while still under control of the crank. It's a really clever design,
but not obvious until you take the parts off the input shaft. Bottom line:
the harder the cable pulls, the tighter the clutch grabs; but when you turn
it with the crank (OUT) , the clutch is "eased" and the cable will pay-out;
albeit with some predictable squealing. I remember the "AHA!" feeling I had
when I got the thing apart and realized how elegantly simple and effective
the design was. One important note in the instructions: after reversing the
winch (OUT...lowering the tower), you should crank (IN) through at least one
pawl ratchet in order to "set" the clutch.
I was able to buy a refurb. kit from Fulton a few years ago for $15 or
so...it had a new pawl, spring, etc...all the critical parts and those
subject to wear or rust. I think I just called and ordered on the landline.
Even if the cost has increased, it's a cheap and easy step to peace of mind!
(hoping his memory hasn't slipped)
----- Original Message -----
From: "Alan NV8A" <firstname.lastname@example.org>
To: "towertalk reflector" <email@example.com>
Cc: "Al Williams" <firstname.lastname@example.org>
Sent: Monday, March 19, 2007 9:49 AM
Subject: Re: [TowerTalk] Tower winch failure
> When I examined the winch on my HDX-555, it seemed that the brake
> mechanism applied permanent friction between the shaft and the toothed
> wheel, but when the cable was being wound in the pawl allowed that
> toothed wheel to turn freely. When the cable was being let out, the
> spring-loaded pawl prevented the toothed wheel from turning, the
> friction being sufficient to prevent free-wheeling and in fact requiring
> considerable effort let the cable out and lower the tower.
> AFAICS, the only way it can free-wheel is if something moves out of
> alignment or if the pawl fails to engage the toothed wheel due to spring
> failure or lack of lubrication of the pivot.
> Without bothering to show the math here, it seemed to me that the winch
> is in no way overloaded unless the whole tower is overloaded.
> Although the documentation package I received from UST included nothing
> about the winch, I found the information online at:
> From this I see that the KX1550 has two pawls instead of one (in
> addition to having the cover over the gears). I can't imagine that this
> would add much to the cost, so I am wondering why UST doesn't use this
> instead or at least offer it as an option: both features would surely
> make for increased safety.
> Alan NV8A
> On 03/18/07 10:57 pm Al Williams wrote:
>> I have been hoping that a knowledgeable towertalkian would offer a
>> 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
>> in preparation for tilting it down. When the center of gravity moved
>> 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
>> Actually I have two k2550 and one k1550 winch and all three were
>> from separate sources with months between the purchases. All three have
>> what I call a "free wheeling" mode and operate similarly. When the tower
>> being tilted up and becomes near vertical the center of gravity takes
>> 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
>> 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
>> the tower back down) but the tower center of gravity has not changed i.e.
>> 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
>> 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
>> cable is subsequently made to become taut again by taking the slack out
>> 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
>> 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
>> can result.
>> When my near accident of the tower falling occurred, I continued cranking
>> 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
>> "snapped" into operation. I don't intend to experiment to confirm my
>> Joe may be correct in that "...the winches are not designed or intended
>> freewheel". However the anomaly seems to be in the design and use and
>> 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
>> a winch failure. It would be easy to confirm this and I hope that
>> will and report it.
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