[TowerTalk] FW: Crank up questions.

[Roger (K8RI) on TT]

On 11/27/2013 3:28 AM, Matt wrote:

A raising fixture similar to the commercial ones is very easy to build. 
Whether the tower will easily adapt to one is something else, but with a 
little ingenuity should work.

73

Roger (K8RI)

> This may or may not be of use to you but thought I would offer an
> alternative.  I have 4 cranks-ups and 2 don't have raising fixtures.   For
> each of these without fixtures I elongated the foundation excavation and
> dropped a 20 ft stick of schedule 40 pipe centered at the appropriate
> location prior to placing concrete.  I welded cap plates and reinforced
> mountings for a 2-ton chain hoist at the top of each of these the pipes.
> Suggest to do the stress and flexure analysis on the lifting loads for the
> tower before sizing the pipe.   I ended up with 6" pipe on one installation
> and 8" on the other (a larger HD tower).  On the advice of my structural
> engineering friend, I fabricated the rebar cages with additional "U" straps
> wrapped around the pipe on a 2" larger radius tied back deep into the center
> of the concrete with angle turnouts on the ends.  - and doubled up on the
> spacing through the bottom (and top for good measure) few feet of the
> foundation.   This is to strengthen the foundation for the side loads (ie
> avoid blowing out the side of the foundation at the bottom corner) that are
> imparted when the pipe is under bending stress.
>
> To raise or lower the tower I just hang the chain hoist on the pipe, connect
> to the tower and she comes right up - very sturdy.
>
> Good luck on your tower project.
>
> 73
> Matt
> KM5VI
>
>
>
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