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brucedownunder2
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Posted: 30 March 2018 at 9:31am | IP Logged Quote brucedownunder2

Hello ,
Well ,I'm stubborn. I'll have to admit ,I need help ,please.

My tower bends so much when I lift it ,I'm too scared to go further .

It's around 100x100x8 back to back bolted angle -structual steel.around 60 feet long .

I have 3 wire ropes , through a couple of sheaved pulleys that ,I thought, would equalize the pullin/lifting load. All coming back to a single winch wire rope.

The winch is strong enough-fine.

My problem is , I start the lift and a bend developes about 3/4 way from the bottom of the tower length.

I've tried moving the point -of-attachment wire ropes ,,helps to some degree .
But really just moves the "bend" to a different area-tried many adjustments.

So, I can,t lift my windgennie,which weighs around 80 kilos,all up .

Would anyone with mechanical lifting experience be able to help .

I live in the gold coast hinterland if that helps.

Thank You

Bruce

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Posted: 30 March 2018 at 9:45am | IP Logged Quote fillm

Hi Bruce,

I am fairly busy at present but could probably come over to have a look in a week or 2 . You can give me a call if you want , you have my number.


Edited by fillm on 30 March 2018 at 9:46am


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Posted: 30 March 2018 at 9:52am | IP Logged Quote brucedownunder2

Thank You Phill , I'll do that .

Stubborn old 73 yo ,but I now know I can,t do these things of yesterday.

Bruce

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Posted: 30 March 2018 at 10:53am | IP Logged Quote Alastair

Bruce,
You already have several connection points by the sound of it. Years ago I used to help a guy who repaired windmills - usually bore pumps. Many of the towers were old and dodgy. He used large planks of wood under the wire at the connection points to spread the stress. Put the planks vertical and try to span as many structural members as you can.


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brucedownunder2
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Posted: 30 March 2018 at 11:43am | IP Logged Quote brucedownunder2

Thanks Alastair,

This is a bit different , it,s not really a structual problem ,it's lifting the long single member length . It requires(I think) , support at intervals ,but the lifting cable has to have an equal lifting force equally along that length at the attachment points .

How this is achieved is what I can't fathom ....

Bruce

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Posted: 30 March 2018 at 5:20pm | IP Logged Quote brucedownunder2

picture of tower



hope this works

OK, so the pic works, now , that is a pic of the old LIGHT F&P wind gennie,so the tower is able to be erected ok with that light load .

Now I have a heavy 'er windgennie and it's heavier, so this is where the problem is .

Not the lifting , but the bending of the steel..

I'll grab some pic's of the pulley block set-up later.

Bruce

Edited by brucedownunder2 on 30 March 2018 at 5:24pm


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Posted: 31 March 2018 at 8:36am | IP Logged Quote Alastair

Bruce,
I assumed it was a fabricated tower not a pole. Apologies.

How heavy is the new generator?


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Posted: 31 March 2018 at 9:45am | IP Logged Quote brucedownunder2


Hi Alastair,
No need for apologies,just thankfull of your feedback ,it's what makes this forum tick.

OK, weight ,it 's a Exmork 2 Kw chinese generator with fibreglass blades ,probably all up weight around 70 Kg. It takes a couple of us to fit first the generator to the mount ,then we fit the blades and tail.

The steel is recovered TV tower structual steel of high quality and bolted with their special high tensile bolts together --sort of equal angle ,back to back .

I've got it rigged with a huge winch ,which used to haul a 30 foot launch out of the brisbane river up a slipway,,so it's plenty strong with 8mm (3/8inch) wire hauling rope.

it's been up and down 20 plus times since I built it ,I have it rigged so that it is a one man operation .can lower it in 3 minutes or so raise it in about the same time .

so , thats about it,

Bruce



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Posted: 31 March 2018 at 4:46pm | IP Logged Quote brucedownunder2


OK found a pic of the bending ,I'm talking about ,and you can see the attachment fixings on the tower steel -I've tried moving these fixings to other places ,but still get bending.
by the way,these attached wire cables are actually one only ,going back to a sheave block . It is then pulled up tight by the winch cable.that may be where my problem is?

Bruce





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Posted: 02 April 2018 at 12:42am | IP Logged Quote yahoo2

brucedownunder2 wrote:

by the way,these attached wire cables are actually one only ,going back to a sheave block . It is then pulled up tight by the winch cable.that may be where my problem is?


the topmost cable takes all the lifting weight, the lower ones are there to just stop things flopping around and hold the weight of the mast. if you are pulling on the lower cable the mast will bend.

I think you have two options,
use a gin pole
or
build a stiffer mast.

Three options for a stiffer mast, large diameter thinwalled tube, lattice mast, or add outrigger stays to the centre section of the existing mast.

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Posted: 02 April 2018 at 6:01am | IP Logged Quote Warpspeed

The crazy yacht guys have fairly similar problems raising the mast on a boat, and there are quite a few discussions and pictures on the internet about using shear legs to step a boat mast.

However, your mast is a lot longer, and a lot heavier, especially with the wind machine mounted at the top.

If I had to do this all by myself, I would also worry about getting it down again at some future date. As I am now almost seventy years old myself, I can really appreciate your situation.

I think I might investigate getting a driller to bore a sixty foot deep hole and fit a a steel liner. Then lower each section down the hole and bolt the next section on top of the first, and so on. Then finally fitting the wind machine on top (at ground level).

Then winch the whole thing up vertically slowly letting out the guy wires as it goes up. It could be lowered fairly quickly the same way for maintenance. If the whole thing is built vertical to start with, the bending problem is avoided altogether.

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Posted: 02 April 2018 at 7:05am | IP Logged Quote brucedownunder2


Thank You Yahoo and Warpspeed for your ideas.

The outriggers ,as in yacht "spreaders" seem to be the easiest way ,if it works ,no reason why not. As you said the most weight to lift is at the far end .

When i lift it or lower it with the lighter windgennie on , it still bends , but once it gets ,say, 45 degrees,things start to straighten out and she is OK. but , of course,most of the weight now is in compression and the base is taking it.

I tried several different attachment points, mostly trying to convince myself "she'll be allright" sort of mental thing.

Phill is coming over when he's got time and we'll sort it out ,I'm sure.

more important to get Ilda home at present ,

Bruce

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