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lifting with pulleys


By imsmooth, Section Mechanical
Posted on Sat Oct 31, 2009 at 05:54:29 PM MST
Any pictures

Does anyone use pulleys to raise their tower with the winch to cut the lifting load?  If so, any pictures of your setup and where you got your rigging hardware?
lifting with pulleys | 9 comments (9 topical)

Re: lifting with pulleys (3.00 / 0) (#1)
by Volvo farmer on Sat Oct 31, 2009 at 08:02:09 PM MST

I'll second that request... A tractor is a nifty, useful thing, but I got some pretty sweaty palms pulling the tower up in front of the 20+ people who came to my erection party. I see a winch and pulleys in my future.

Volvo Farmer




Re: lifting with pulleys (3.00 / 0) (#2)
by tanner0441 on Sun Nov 01, 2009 at 01:57:22 AM MST

Hi

I use a 12V winch designed for pulling boats onto trailers.  Pulls about 3000 pounds, nylon webbing rated over 4000, I normally also push the mast from the back as well until it is past 45 degs.

Brian.

[ Parent ]



Re: lifting with pulleys (3.00 / 0) (#3)
by frackers on Sun Nov 01, 2009 at 02:19:13 AM MST

I use a trailer winch - the sort of thing used to pull a boat onto the trailer.

Mine came with 5m of 5mm HT cable which was way too short but the spool had plenty of room on it so I got the local wire rope supplier to reuse the hook on the end and replace the cable with a 12m length. I think the cable is rated at just over 1 tonne.

The original 5m length came in very handy making up safety wires to go across the guy adjusters.

5:1 ratio on the crank and a good solid pawl to lock it in any position it works great - I just took my 3m mill down this afternoon for its 6 monthly check (only 2 months late!!) - it took less than 15 minutes on my own to let down 250kg of tower and mill and position it on the stand.

Everything was clean after generating nearly 250kw/hr this last session:-) Just got to remove the dissected flies from the leading edge and rebalance the blades as I didn't do a very good job a year ago.
Robin - Down Under (or are you Up Over)



Re: lifting with pulleys (3.00 / 0) (#4)
by TomW on Sun Nov 01, 2009 at 02:34:48 AM MST

smooth;

I use a single pulley rigged to the gin pole and a cable through that back to near the hand winches. The pull is smooth and while less effort to crank it is 2X the turns to get the same lift distance.

Folks always say it is easier on the lifting gear this way. I am not sure about thet. Not sure you would want to lift 1000# with a 500# rated winch this way is my point.

I tried truck lifting on my short 4 leg tower. Too coarse for my liking. With the winch setup I can lift it 1/16th of an inch if i want and the truck was much coarser. Direct pull lifting from the winch is ok but again takes more effort on the handle. Be sure your cable length is sufficient when using pulley[s].

You can use multiple pulleys, too but it takes a lot of cable but multiple reductions can get you a LOT of pull from a relatively small force on the winch handle. Do not mistake me for an expert but I have worked around this type stuff a lot over the years and it is all simple physics

I do not have any good photos of the rigging but a properly sized, solidly attached pulley and proper cable is about all you need to worry about.

Really busy filling the woodshed lately but maybe I can snap some pics of them today.

This is the winch on the new 40 foot tower for the 12 footer I will not get done this year.

The one on my 3 foot 4 leg tower is a worm drive Harbor Freight one that weighs less than the handle on that real winch above. It works OK but needs some repairs on bushings and thrust washers or simply buy another. They are pretty cheap but do work.

Maybe get some pics later today. No promises this time of year. Sun goes down pretty early these days.

Tom

Ignarus can exsisto rememdium. Sardus est forever




Re: lifting with pulleys (3.00 / 0) (#5)
by Janne on Sun Nov 01, 2009 at 07:53:05 AM MST

A picture of my pulley system, it adds the reduction of 9 to 1..

http://anotherpower.com/gallery/album101/P1030220
contact: #otherpower @irc.otherpower.com



Re: lifting with pulleys (3.00 / 0) (#6)
by ubud on Sun Nov 01, 2009 at 09:35:26 AM MST

Yes on lifting with pulleys.
I'm raising a 48' HDBX Rohn tower with 7' extension out the top.
My gin pole is in a fixed position at about 70degere 18' long, the winch is a 3000lb. boat winch re-cabled with 3/16" multi strand.
cable goes to top of gin pole, around pulley to top of tower, around another pulley, and comes back to top of gon pole.
my lower time is less than 1 min.
raise time is about 1min 15 sec., loaded with mill in place.      
Frank
CIWIH (cause its what i had)


Re: lifting with pulleys (3.00 / 0) (#7)
by scoraigwind on Sun Nov 01, 2009 at 11:10:24 PM MST

Pulley ratios cannot be taken at face value because friction adds quite a bit to the work.  So a single pulley for example will not reduce the force required in half exactly.  But it does help a lot.

Using vehicles is usually a pretty scary way to lift a tower.  You will need one with a very low gear indeed and plenty of weight and a nice dry surface.

The best tool in my opinion is a griphoist/tirfor type of rope hoist.  Personally I favour the jet rope hoists because they cost less and are easier to use.  I have not encountered any safety issues.

http://www.southern-tool.com/store/wire_rope_grip_pullers.html

Slow and safe.
Hugh Piggott http://www.scoraigwind.co.uk



Re: lifting with pulleys (3.00 / 0) (#8)
by Flux on Mon Nov 02, 2009 at 12:08:56 PM MST

I agree with this, the friction on simple pulleys can be far more than you expect. A single pulley is a great help but more than that means a lot of rope and if you use a winch a large drum. You probably don't gain over a stronger winch with a shorter pull.

If you happen to have a low power winch and plenty of thin cable then it may be worth the effort but unless you use pulleys with ball bearings you can soon get down to 50% efficiency with high ratios.

If you have to use a vehicle then a pulley reduction is a good idea to keep the speed down to something you can control. I agree with Hugh that most vehicles are far too fast for comfort.

Flux

[ Parent ]



Re: lifting with pulleys (3.00 / 0) (#9)
by SparWeb on Mon Nov 02, 2009 at 01:16:14 PM MST

Hugh,
I only just learned about the griphoist from reading Paul Gipe's book.  Before that, I never considered one, even though I was looking for a suitable winch for my tower.  It took some time and research to learn that it is not the same as a come-along, because I've never used one personally.  Too late for the tower, I have the winch already, but now I'm determined to get my hands on a griphoist anyway, just because it sounds useful for many other things.
Steven Fahey
[ Parent ]


lifting with pulleys | 9 comments (9 topical)
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