Roger (K8RI) wrote:
> Is there a good description of the mechanics for a crank up mast on the
> web? I'm looking at three sections or more. I've found a couple of
> basic designs, but I haven't be satisfied with the safety aspect and
> they were basically just crank up poles. Standard pipe (schedule 40)
> might or might not be strong enough so some sections could be schedule
> 80. In addition to the raising cable(s) there need to be guides to
> prevent each section from rotating inside the next larger size. A
> single cable, although easy to route has to support the entire weight so
> it should have some sort of latching mechanism. (a single pulley in the
> base of each section with a single on the outside at the top of the
> section) It'd be even nicer if each section could be raised and lowered
> independently of the rest which of course would mean a winch mounted at
> the top of the previous section which would add overall weight and a
> larger wind profile. Ideally the entire mast would rotate. Also the
> *innards* need to be accessible if the cable breaks or hangs up.
>
Hi, Roger:
I've never built one but we have quite a few 30-foot crankup masts at
work that are made from thick-wall square aluminum material. The lower
part of the mast is probably 6-inch outside dimension. I believe these
are commercially available but there is nothing on the masts to identify
the manufacturer. Neither have I ever paid any close attention to
details of the way the cable and crank assembly are configured.
The square material obviously solves the rotation problem and may be a
solution if the material is not cost prohibitive.
Have fun!
73,
Jack, W6NF
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