I'm about to pull a HWS671 vertical. There's a pad welded on the outer
section. For those with an erection fixture it was used to install a
pulley wheel to winch up the tower. I don't have a fixture, but I do
have a tractor that I intend to pull it up with. The plan is to use 1/4
inch 7x19, same stuff the tower uses, on a thimble around a bolt through
the pad ordinarily used for a pulley with the erection fixture.
The question is, what grade of bolt do I buy that will pull it up and
not break? I see it as a fight between ductility and brittleness, grade
8 being brittle for shear loads like this. The hole is for a 5/16 --
which seems a bit small to yank up this tower. I'm sure it used to work
when these towers were new 30-40 years ago. The alternatives are, drill
out the hole for a bigger bolt or use a chain, either one putting the
galvanizing at risk.
HWS671 is a 4 section 71 ft middling strong crankup weighing about 1400 lb.
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