[Towertalk] CRANK UP TOWERS - Not a panacea
Frank C Travanty
w9jcc@juno.com
Fri, 15 Mar 2002 20:02:34 -0800
Jerry, what you suggested below is pretty easy to do with a crank up
tower (with some restrictions). I decided in 1968 to not be a climber and
go with the crank up type of tower. What I'll describe is what worked
well for me over the past 34 years of using crank-ups. The procedure has
been the same for both types of towers I have owned, although Tower #2
was a bit more challenging the first time. My feet never go more than 5-6
feet above the earth.
Tower # 1 Tristao CZ-454FS with TH6DXX - 9' mast, Fulton 1550
winch.
Tower #2 US Tower HDX555 with C31-XR and WARC 2/2 stacked - CR20
mast (140lbs)
First of all I NEVER climb the tower, even when fully nested. Develop a
mind set for safety. ie (These beasts are dangerous even when they are
full horizontal - its pretty easy for a co-worker to manually tug the top
section of an HDX555, but tough on your finger if it gets in the way -
don't forget to push it back in prior to going vertical ... etc..)
All of the work is done using an eight foot and five foot stepladder (if
needed)
I can do all the work myself, although the XYL usually helps.
The towers both use raising fixtures, that allow them to be tilted at the
base.
On initial installation, the rotor and mast is installed first with the
tower horizontal. Positioning/aligning of the rotor and mast is done
using a light weight mast (in my case I use my old 9' mast which only
weighs about 20lbs). Then the 20' mast is inserted, and the five foot
ladder in conjunction with adjusting the tower tilt, is used to relieve
any bending moment at the thrust bearing. - secure the rotor to the mast.
The sleeve below the thrust bearing appears to take the brunt of the
bending moment when the ladder is removed.
The rotor azimuth needs to be determined so that when the tower tilts,
the elements are horizontal to the ground, at the proper azimuth.
The antenna is fully assembled in the ground first. - Then separate the
boom sections.
The antennas are attached to the mast, starting with the boom to mast
section and adding ~six foot assembled boom/element sections, while
tilting the tower higher for each section to be added. When half the
antenna is assembled, tilt the tower to vertical, rotate 180 deg. and
repeat the process for the other half of the antenna.
I can reach the "feed" section of my C31 with using the eight foot step
ladder, by simply tilting the tower. It's pretty easy to reach any part
of the antenna by removing boom sections if needed.
73,
Frank W9JCC
On Fri, 15 Mar 2002 07:51:42 -0800 Jerry Kincade <w5kp@swbell.net>
writes:
> I keep hearing this "ground level" phrase tossed around, and I'd like
> to
> hear from crankup owners exactly what brand and model towers they
> are able
> to work on at "ground level" *with antennas installed*, assuming the
> tower
> is installed in the clear and not next to a roof. Unless you don't
> have
> anything but a mast on top of it, all the sufficiently tall (70'+)
> crankup/tiltovers I looked at cannot be tilted to the point you
> don't need a
> long stepladder to work around the mast, rotator, or baluns/coax. At
> best,
> you can get the actual mast tilted over to maybe 20'-24' or so
> before
> something hits the ground. So as far as I can see a TALL stepladder
> is still
> needed, which is far more dangerous to climb than a tower,
> especially if you
> have to handle anything heavy or long, which you eventually will. If
> you've
> ever had to climb a 16' or 20' wobbly, spindly stepladder carrying a
> load,
> you know what I mean.
>
> Also, I'd be interested to hear how to safely change out a rotator
> or check
> for binding on a thrust bearing on a fully loaded mast when the
> whole thing
> is horizontal, with a zillion pounds of side pressure on the bottom
> end of
> the mast. Knottly problems like this likely lead people to take a
> chance and
> climb a "nested" but not tilted tower, "just this once". So they've
> ended up
> climbing anyway, and climbing a tower that isn't designed for
> climbing to
> boot. I've seen a few fixed towers I thought were too dangerous to
> climb,
> because of deterioration or half-baked installation. I've never seen
> a
> crankup I thought was safe to climb.
>
> In the end, I went with Murpy's #1 Law of Mechanics: "The Number
> Of Things
> That Can Go Wrong = Number of Moving Parts Squared". So I put up 80'
> of
> strongly guyed Rohn 45. Using K7LXC's double safety lanyard climbing
> method,
> I'm totally comfortable up there now, other than getting a bit tired
> if I
> have to go up two or three times in a row, but that's only because
> I'm a lot
> older than most of you young whippersnappers out there.
>
> Thanks to all for all the good inputs and ideas, this is still the
> best
> reflector on the market.
>
> 73 and Think First, Climb Second.
> Jerry W5KP
>
>
> >Why climb? That's what the
> > point of my argument was --- the crankup tiltover can be lowered
> to ground
> > level for any servicing. I replace any coax, any tower cabling,
> and
> > adjustments, any routine maintainance from the safety of ground
> level. >
>
>
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>
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