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Author Topic: Tower lowering questions  (Read 3673 times)
WA8MEA
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« on: October 31, 2012, 11:06:10 AM »

I've got some friends of my son coming here Saturday, and we are lowering a thirty foot tower with about 30 feet of combined mast pipe/fiberglass Comet dual band 2 meter/70 cm antenna attached to the tower.

I have turned this into a tilt over tower, using some titanium pipes, nuts and bolts my neighbor machined drilled and gave to me. (He owns a machine shop)

We simply hammered these titanium pipes into the ground, about four feet deep.  I never did cement.  My neighbor claimed that because the tower is aluminum, not very tall and we have some pretty think clay soil here, concrete really wasn't needed to secure the titanium pipes.

Tower went up like a breeze years ago.  But....it has never come down since that time. (And lowering is NEVER as easy as raising!)  Saturday will be our first time lowering it.  I don't want anyone to get hurt, so we are taking every precaution. (I told the boys that if they feel the tower getting away from them....let it fall and get out of the way.  It's not worth getting hurt.)

It is somewhat top heavy because of the extra 30 feet above the tower.  So I am not sure if walking it down by the five of us is going to prevent the bottom pipes from popping out of the ground.  And....I really don't want the biggest fella standing on the bottom of the tower, either.

Will placing a rope about 25 feet up the tower help to alleviate the chance the bottom popping up and relieve some of the top heaviness?  If we've got a couple of these young men pulling on our VERY high load/high test rope, while the other fellas are walking it down....does this help relieve a lot of the force at the bottom of the tower that might make the bottom lift upward?

(I hope I explained this well enough)

73, Bill
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W8JX
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« Reply #1 on: October 31, 2012, 11:15:11 AM »

I would suggest a 10 or 12 foot 2x6 with a notch cut in end to catch/prop tower when lowering it to give you backup control. You can place it between tower and ground as needed to check decent and take a break and reconfigure.
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W8ATA
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« Reply #2 on: October 31, 2012, 06:13:58 PM »

I have been taught to place the anchor point for a rope or cable at the two thirds up point of the entire structure. Your concern for the bottom kicking out is valid. Maybe you will get some suggestions here. Above all be safe and don't do it on a windy day.

73,
Russ
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WA8MEA
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« Reply #3 on: October 31, 2012, 07:05:55 PM »

Thanks, Russ.

I am well familiar with the bottom kicking out since my Dad and I put up many a tower when I was a youngster.  He was on the tallest hill in our town and wanted to get a particular station on UHF from Detroit.  So he had a MASSIVE bow-tie VHF and Yagi UHF amplified system.

Dad had a tilt over tower that was far from aluminum.  Cheesy  It had a floor and walls surrounding the bottom two feet to put sand in it to help keep the bottom down.  Dad NEVER put sand in it....opting to have me STAND/SIT on the bottom instead!  It was safe.  Everything was in concrete and I weighed more than a couple of bags of play sand.  We never needed to use rope, either.  Dad and his neighbor just walked it down.  Now had I decided to jump off the bottom....those two would have had a bit of a problem.  Hi.  It was actually kinda fun "riding the tower" and fond memories of the good ol' days.  Then one day Dad decided to switch to one of those new fangled "banana towers" to gain another ten feet.  BIG mistake.  Kept having problems with the bottom kicking out.  He finally took a long length of well pipe and just used that to secure the bottom.  He bent the hell out of the pipe and bottom of the tower doing that, but it was sure easier to take up and down.  Why did we have to raise and lower this system all the time?  Poor Dad would either have the rotor or the amp go bad on him, so he had to replace constantly.  Then came the invention of cable TV.  That ended that!

I could have used concrete and it would be free standing.  But since I placed it next to the garage, I have a large brace bolted to the side of the garage with the titanium pipes four feet in the ground.

Ya know, telling you this story just gave me an idea.  Maybe I can "ride the bottom"....just like when I was a kid.  I'm 240 lbs.  Two of the young men can man the rope and two others can walk it down.  Or....if we see the bottom starting to give, I can head over to the bottom and stand on it....

In any event, I've got four pickup truck tires we are putting in line with the tower....just in case we can't handle it.

Not suppose to be windy here Saturday.  Sandy should be long gone....

It's an unusual case.  The tower really is not that heavy or tall.  It is the matching length of heavy duty mast pipe on the top of the tower that is complicating the lowering, because that pipe is gonna bow....

73, Bill
« Last Edit: October 31, 2012, 07:08:43 PM by WA8MEA » Logged
WB2WIK
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« Reply #4 on: October 31, 2012, 07:15:21 PM »

Hams do all sorts of nutty things. Wink

Installing a foundation without concrete can be dangerous no matter what the "earth" composition is.  But it sounds like you're aware of the dangers and are taking precautions to avoid injury.

Training everyone involved to have a "fall clear zone" in case of a mishap is a great idea.
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WA8MEA
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« Reply #5 on: October 31, 2012, 07:43:46 PM »

BTW, John....great idea with the 2 x 6.  Never occurred to me.  But we've got plenty of lumber here.

And thanks Steve for your comments.  Many reasons why I did not want to use concrete.  One of them is always the possibility of having to relocate.  And I wanted to keep those wonderful titanium pipes my neighbor custom made for me.  Funny thing. 

We have spared no expense on safety.  I did not own any real rope....just some stuff for fishing boat anchors.  So I went to my long standing hardware store owner (and friend), and he set me up with the best rope he had in stock, with a bit of a price break since it was so expensive.

The next couple of days are the preliminaries.  Gotta remove a dipole that has a center insulator dangling about 2/3's up.  And gonna loosen the nuts and bolts on the bottom pipes.  I've been spraying with Liquid Wrench the past few days.

73, Bill

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WN2C
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« Reply #6 on: October 31, 2012, 08:18:03 PM »

Why not just get a crane to do the job. It would be less expensive than any medical bills or possible lawsuit you may incur.  Unbolt from the top of the first section and have the crane lift it and lay it down.  Or at least remove the the mast section. you could use an A frame when lowering it.  Good luck but be safe.

de wn2c  Rick
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K9YLI
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« Reply #7 on: November 01, 2012, 08:07:03 AM »

 MY ideas..  we have set up  30 foot towers at field ay  with just man power.
If possible.....   good rope tied above the 20 foot point.. then  opposite the  tilt direction
snub around a tree, or anchor to  vehicle and use   block and tackle or  come-a-long.
this will hold the weight  only to the  45 degree point. 
if you have the space,, a very sturdy  ladder and a pickup truck. align the truck and its
path.put the ladder against the front of the bed.   and against the tower afterit has tilted about  15 to 30 degrees, depending on the  opposite side method.
then  idle the truck away, with intermediate  blocking  ladders to allow reposition of  longest ladder,, (make it shorter)
Adaquate persons to stabilize the ladder  for side sway,  ropes to each side with personell  would be good. ..   
I have pushed up a   power pole this way..  the hole was tapered so it had to fall in..

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K8AXW
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« Reply #8 on: November 01, 2012, 09:24:56 AM »

MEA:  IF I understand this situation right you'll be lowering the tower pivoted on two titanium pipes driven 4ft into the ground.... no cement.

When you put this tower up you pulled/pushed the tower up which applied pressure to/on the titanium pipes.

Now when you reverse this procedure, you will be lowering the tower with the base of the tower trying to pull the titanium pipes out of the ground!

Without knowing how solid these pipes are I would suggest you make sure everyone on the job knows where they're to be and what to do if something happens.

A 30ft tower is not very high and you shouldn't have any problem.... as YLI points out.  Just be aware of the difference in pressures between "going up and coming down."

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K4DPK
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« Reply #9 on: November 01, 2012, 08:01:56 PM »

If I understand this correctly, you have a thirty foot tower, with another thirty feet of mast sticking out the top for a total of sixty feet, with antennas on top.  You only have the support in the ground four feet, in clay?

That is a recipe for disaster.  If you use a ten foot piece of wood or something to support the tower, you will only be able to reach it well below the half-way point.  That will behave as a fulcrum and will multiply the upward force to extract the support out of the ground.

You need to support the tower from above.  Is there a tree nearby?

Is there some way you can approach the base with a large vehicle, and fasten or clamp the base to the bumper of the vehicle?  That sort of system would add weight to the base and (maybe) offset the forces tending to pull the base out of the clay.

I think you should consider renting a cherry picker.  

I think there is a good possibility for serious injury with the plan you have proposed.

Phil C. Sr.
k4dpk




« Last Edit: November 01, 2012, 08:09:27 PM by K4DPK » Logged
K3GM
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« Reply #10 on: November 02, 2012, 04:54:38 AM »

If you're intent on doing this, I'd first establish a "bail out" procedure and clear a fall zone in case things go wrong.  A rope placed up the tower with a fulcrum point as high or higher such as a roof peak with several men on the end will take the weight off the others that are walking it over.  I helped walk over 50' of eve bracketed steel tower using the rope method and the aid of a tree trunk as a windlass.  But the procedure whould be clear to everyone before attempting this.  You have no idea how much weight that extra 30 feet of mast adds when you begin to tilt it over.
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WA8MEA
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« Reply #11 on: November 02, 2012, 11:30:19 AM »

All is good.  I have installed a HUGE eye bolt through the wall at the bottom of the garage....with a logger chain wrapped around the bottom of the tower several times and chained to the eye bolt.  If the bottom does decided to come up....it won't move but an inch or two from some slack in the chain.

I guess many are missing the point.  This system is NOT heavy in total weight at all....just TOP heavy.  It's a fiberglass vertical, not a beam.  But we still don't want to lose control of the tower with the bottom swinging out from under us.  The logger chain will now guarantee this.

I did the preliminaries this morning.  I took down the horizontal support pipe for the 60 meter dipole and moved that 60 meter antenna out of the way.  Climbed up and securely wrapped the rope around the upper part of the tower and brought both ends down to the ground....tying a knot towards the ends and then about a yard or so up....giving us guys on the rope some added grip.

We will file a report tomorrow evening on how everything is operating....

Bill
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K4DPK
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« Reply #12 on: November 02, 2012, 12:49:36 PM »

Good luck!

BTW, will you be selling tickets?

Phil C. Sr.
k4dpk
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KE3WD
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« Reply #13 on: November 02, 2012, 01:28:58 PM »

Good luck!

BTW, will you be selling tickets?

Phil C. Sr.
k4dpk

How much for the beer concession? 

73
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K9YLI
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« Reply #14 on: November 03, 2012, 07:35:46 AM »

  Sop far i think the obvious has been missed.

climb the tower and  loosen the clamps and   let the  30 foot mast  slide down
to as close to the  top of the tower as possible.
reduce the  top heavy effect...

duh
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