[TowerTalk] lowering a lighting tower

[jimlux]

Tom Rowan wrote:
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> Hello I have an alleged accident where a guy says he was lowering a lighting
> tower with a K1550 fulton winch, when the handle spun out of control and the
> mast crashed down. I understand the mast is held by friction disks as it is
> being lowered. Does anyone know how this could have happened?
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Those friction clutch/brake winches do have that failure mode.  If they 
are cranked too fast or overloaded, the little brake pads get hot and 
"fade" (just like car drum brakes), once it starts to slip, it runs 
away.  In some kinds (I don't know about this one specifically) the 
brake is designed (like drum brakes) so that it brakes more in one 
direction (down) than the other (up).  for these, it is possible to 
install it backwards, as I recall (to accommodate situations where you 
want the braking when spooling IN as opposed to spooling out

Now, whether such an event can occur on a winch operated within specs 
(load, speed) and which is well maintained?  The only cases where I've 
seen this kind of thing occur have been where there was a significant 
overload or there was some other factor (water being splashed around). 
The electric winches/hoists from Grainger/Harbor Freight have the same 
sort of scheme inside.