[TowerTalk] FW: Crank up questions.
Roger (K8RI) on TT
K8RI-on-TowerTalk at tm.net
Wed Nov 27 04:12:52 EST 2013
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.
> 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.
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