David Jones wrote:
> I have a Tri Ex 588 tower I am looking to add a winch to raise my
> winch and tilt it up right. I am looking at a 10,000 pound winch to
> attach to the roof of my house for raising and lowering it from to
> ground to install antenna and do maintenance. My question is that the
> winch is for 12 volt operation wiith automatic braking. I know that a
> hoist is more suitable for stable holing power for in and out cable
> pull. Can the winch be used safeely for the raising and lowering
> since it has automatic braking? I was hoping it would work since the
> total pulling power is way over the limit needed to raise the tower
> since the whole tower only weighs less than 500 pounds. Thank Dave
> KB0CVV
Is this an automotive/4WD type winch? It might not actually be able to
pull 10,000 lbs, especially with some wraps on the cable drum, etc.
"safely" meaning what? I'd not trust it enough that I'd walk under a
load supported by it. It might hold, it might not. The automatic braking
feature sometimes works, sometimes doesn't, especially if it's not
tested regularly: I've had more than one experience where an electric
hoist failed to hold, and the load came down (not a free fall, it's
true, but still faster than was pleasant to watch).
As far as the tower mass and the load on the winch: you've got to look
at where you're attaching to the tower, and the leverages and angles
involved. if your winch is up high, and the tower starts to lay over,
the angle of the winch cable to the tower starts to get less than 90
degrees. There's also the whole load vs angle of tower problem.. when
standing vertical, it's real small, but as the tower lays over, the load
keeps getting bigger. You've got a nasty situation in general with this
sort of thing, because the load is real small when you first start
leaning over, then it gets rapidly higher as it goes further, so if
something's marginal, the "excitement" will be a rapidly going downhill
sort of thing. (This is why the falling derrick scheme is popular, it
helps keep the load more even)
Can your roof (or whereever you're attaching the winch) take the load?
Again, a falling derrick scheme could probably use a suitable piece of
pipe as the extra mast, let you put the winch on the ground, and not
attach to your roof at all.
You might also consider putting the winch on the ground (shorter wiring,
etc.) and a pulley up high. You could even put the winch and pulley on
the tower, run the winch cable up the tower, thru the pulley, to a fixed
anchor up high. That way all the "moving parts" are accessible for
servicing and inspection.
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