[TowerTalk] Tower Lift (with crane) with Antenna's Already Installed

[Charlie Gallo]

On 11/18/2013 Richard Thorne wrote:

<snip>
> So the question (I'm an accountant not an engineer) will the tower stay
> straight up and down or will it tilt due to the weight above the tower/crane
> attachment point?  I honestly don't know what the affect will be since the
> antenna's have the weight distributed along the boom, not directly above the
> fulcrum.
<snip>

OK, here is a rule of thumb for anything hanging from a single point

It will tilt

The real question is "How MUCH will it tilt, not if it will tilt"

The real answer is to plan your lift in such a way that it tilts as LITTLE as possible.  Generally, you want to lift as if you were lifting by the mast, but actually lift the tower (so stuff doesn't slip off).  Basically you are going to want lifting slings (LONG slings) that go around each leg of the tower near the top (yes, 3 slings - or on sling and 2 guys) AND a guy from the top of the mast to the hook to keep things centered.  Then you'll only get a small amount of tilt, and you manhandle things back into position with your drift pins/spud wrenches

Pretty much the only times you don't get tilt when lifting ANYTHING is if they lift on a spreader engineered for the specific load (which will probably cost you more than the rest of the job), or it is a 'simple' lift like an I beam, and someone measures the beam, gets the center, and they do a few inch trial lift to adjust the lift point.  Even with measuring, you usually get a little bit of tilt (few inches over say a 20 ft beam)

-- 

-- 
Charlie
www.baysidephoto.com
www.thegallos.com