[TowerTalk] Help With Rohn 25 and Winch
Grant Saviers
grants2 at pacbell.net
Wed Jul 20 22:43:09 EDT 2016
As long as your eave is strong enough, that winch should do the job
without any more pulleys to gain mechanical advantage. That assumes the
other pulleys are good ones with low friction, although it is not clear
in your post what "a series of pulleys" means. 800# pulleys vs 2000#
winch seems like a bad idea. The cheap (eg Zoro) 800 and 2000# pulleys
and turning blocks are steel pulleys on steel bolts, without grease
fittings or bronze bearings, pretty much junk for your application since
they are out in the weather and probably not rated "for lifting".
It would be wise to add a 2 x 8 or larger inside the eves across several
studs and bolt thru with threaded rod to the top turning block. Better
yet, add some diagonal bracing (e.g. an angle iron with end cut and bent
and drilled for lags or bolts) from the 2 x 8 back to the attic floor,
onto a 3/4" sheet of plywood nailed or screwed to the joists. Eave
studs have little structural resistance to pull over and the sheathing
only has small nails holding it onto the studs. I've done this at two
houses, one with a 30' of R25 and a bigger beam on 15' of exposed mast
and they and the house survived hurricane winds.
Grant KZ1W
On 7/18/2016 9:15 AM, Ross Lambert wrote:
> I put up 16 feet of Rohn 25 g ( 10 foot section and a 6 foot section. )
> This tower is bolted to upper section of house near eave of house at the
> 10 foot up from the
> a 3 ele tribander (TA33M ) and a 3 element 6 meter beam is going on it.
> The tilt over base is on a flat roof .
> I would like to use a winch and block and tackle to tilt over and tilt up
> tower.
>
> I bought a D and L WG2000 worm gear winch
> 7/32 aircraft winch cable
>
> I plan on routing the cable through a series of pulleys rated at 800 lbs up
> to the ten foot level
>
> The question is should I use a block and tackle arrangement between the
> wall of the hous and the tower?
>
> And will this short tower be ok with the winch? I'd like to be able to
> raise and lower the tower with the antennas on it.
>
> The antennnas dont weigh much. The tribander will be just above tower top
> and the 6 meter 4 or 5 feet above.
>
> Any comments or suggestions?
>
> Please copy your response to e-mail address below
>
> Ross
>
> K3HR
>
> k3hr at k3hr.com
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