Tower Raising fixture ideas ?
DOUGLAS SNOWDEN
moving into. I would like something I can handle easily by myself, meaning
either crankup or tiltover aluminum. I was thinking about maybe a Heights
or Universal aluminum 50-60ft on a tiltover base, not the foldover base. To
save money I would like to fabricate some sort of steel post along the side
of the tower, with a pulley/winch arrangement. Not being an engineer, I am
looking for ideas on how high the pole shoule be - maybe as a ratio of the
tower height and what would be a good safe diameter pipe. Am I looking for
trouble? Typical commercial foldover mechanisms are expensive. Should I
just rent a cherry picker for the occasional times I would be tilting the
tower over? As light as it would be that should be a solution.
Doug
N4IJ
'Doc
Take a look at a few of the tower sites that show
accessories. You don't have to buy from them, but you
can copy their fixtures...
'Doc
Roger Halstead
Raising a tower whether fold over, or using a raising fixture is a
whole series of tradeoffs.
Some things to think about:
A lot depends on how much room you have...can you lay a 50 foot tower
straight out?
Actually with a tilt over base three men can walk up a 50 foot ROHN 25
G, but not with much of an antenna on it. At 40 foot three men can
walk up the tower with a small tribander on it.
If you want 50 feet and plan on using a raising fixture (post int he
ground) as opposed to a fold over, it can take a pretty hefty post
with a heavy base.
Remember that with a raising fixture the loads exerted on the base
hing(s) can be tremendous. Make sure th tower is capable of
supporting that much diagonal pull. When you start raising almost all
the pull is at 90 degrees to the base. Something the tower legs may
not be strong enough to support.
The taller the fixture the less load on the tower legs. The farther
out the attachment to the tower the greater the load on the tower legs
and up to a point the less effort required to raise the tower.
When pulling a tower up using a raising fixture the two points with
the largest forces are the base and the attach point. Raising the
tower so it's already part way up...supported by a ladder, or some
such device can reduce the side load at the attach point and base
substantially. Depending on the size/weight of the antenna, mast, and
rotor the weight supported at the attach point can be considerable.
>
The taller the raising fixture and the farther out the attach point
(in general to a point) the less side load at the attach point.
OTOH the taller the raising fixture the heavier the material required
for the fixture.
One additional point. IF you use a raising fixture AND have several
men helping by lifting and pushing against the tower it can greasily
reduce the effort required by whoever operates the raising fixture and
it can reduce the side loads on the tower at both the attach point and
the base.
Typically fold over towers are reinforced at and within some distance
of the pivot point.
Mine, we installed one section at a time using a gin pole.
http://www.rogerhalstead.com/tower.htm
Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)
>
>Doug
>
>N4IJ
>
>
DOUGLAS SNOWDEN
to do this, if I should. I figure an aluminum tower will be easier to
raise, but of course at the same time aluminum will be weaker than steel.
The foldover system that Heights towers has is somewhat amazing to me. It
seems to me that there would be a huge amount of stress on the system.
Doug
Doug
"'Doc" <w5...@cwis.net> wrote in message news:3F381A60...@cwis.net...
Tarmo Tammaru
other than a crankup tower. Bite the bullet and buy the stuff that is all
supposed to work together. If you extrapolate from how they are set up, a
raising fixture for a 60 foot non crankup tower would be about 30 feet high.
Tam/WB2TT
"DOUGLAS SNOWDEN" <sno...@peoplepc.com> wrote in message
news:vje2dv9...@corp.supernews.com...
Brian Kelly
Engineering a tower installation is not rocket science but only for
for those educated and experienced in the field of structural analyses
and design. Towers "engineered" by those who don't have appropriate
backgrounds are potential deathtraps.
Don't raise a full-height tower via a pole, cherry picker or sign
crane unless you have a grip on all the reaction forces & streses on
the structure based on the location of the lift point.
Select a catalog tower and stick 100% to the manufaucturer's
installation and operation directions. It'll cost more but you'll
sleep better.
> Doug
>
> N4IJ
w3rv
Roger Halstead
After seeing the work I put into mine, the size of the parts, the
strength of the guys, the 17,000# guy anchors, my wife put her foot
down and said no more climbing the other guy's towers around town.
Course, she says I shouldn't be doing that kind of work for the young
guys at my age although I hear no complaints when I go up and work on
mine. http://www.rogerhalstead.com/tower.htm
We had one who was going to install a 100 foot 25G and mount the rotor
at the base. Although basically a sound idea in theory, he
unfortunately was using 1 1/2 chrome molly tube with 1/2 inch wall
and the rotor was supported between the tower legs about a foot above
the base.
I could barely manage to pick up one section of the tube and he had 6.
(I'm not all that big, but I do lift weights) Imagine the weight on
the rotor and tower base, let alone the momentum from the mass even
without the antennas.
We had a longggg talk.
He decided to mount the rotor on a separately supported steel plate
anchored to big concrete blocks on either side, but finally abandoned
the idea as getting too complex.
Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)
>
>
>> Doug
>>
>> N4IJ
>
>w3rv
Brian Kelly
> >Select a catalog tower and stick 100% to the manufaucturer's
> >installation and operation directions. It'll cost more but you'll
> >sleep better.
>
> After seeing the work I put into mine, the size of the parts, the
> strength of the guys, the 17,000# guy anchors, my wife put her foot
> down and said no more climbing the other guy's towers around town.
> Course, she says I shouldn't be doing that kind of work for the young
> guys at my age
She's right.
> although I hear no complaints when I go up and work on
> mine.
She knows when to stick and when to fold.
> http://www.rogerhalstead.com/tower.htm
Yumpin Yesus! Whatta "backyard" antenna farm!
> We had one who was going to install a 100 foot 25G and mount the rotor
> at the base. Although basically a sound idea in theory,
Done all the time and saves a lotta climbing.
> he
> unfortunately was using 1 1/2 chrome molly tube with 1/2 inch wall
> and the rotor was supported between the tower legs about a foot above
> the base.
No . . ! Good thing he didn't design yer nice old Debbie . .
> I could barely manage to pick up one section of the tube and he had 6.
> (I'm not all that big, but I do lift weights) Imagine the weight on
> the rotor and tower base, let alone the momentum from the mass even
> without the antennas.
>
> We had a longggg talk.
I'll bet.
> He decided to mount the rotor on a separately supported steel plate
> anchored to big concrete blocks on either side, but finally abandoned
> the idea as getting too complex.
Ya take the vertical antenna & mast load out with a thrust bearing
either in the top plate or somewhere close to the top, run some loosly
guided 2-3" EMT down the tower and . . . does a great job of knocking
down the torsional start/braking/wind spikes throughout the system AND
reduces the number of climbs. A second thrust brg just above the
rotator is even better. I dunno where they come from.
> Roger Halstead (K8RI EN73 & ARRL Life Member)
> www.rogerhalstead.com
> N833R World's oldest Debonair? (S# CD-2)
w3rv
Roger Halstead
>Roger Halstead <newsg...@rogerhalstead.com> wrote in message news:<23tnjv8fqktm5bi3c...@4ax.com>...
>> On 12 Aug 2003 09:08:08 -0700, ke...@dvol.com (Brian Kelly) wrote:
>>
>
<snip>
>
>> http://www.rogerhalstead.com/tower.htm
>
>Yumpin Yesus! Whatta "backyard" antenna farm!
>
Thanks...I think...<:-))
All put up by hand...Mine...with the aid of a friend pulling on the
rope to the gin pole now and then. Took something like 2 to 2 1/2
years to finish. When I started I figured maybe a couple of months.
"One of these days" I plan on going up there and shooting a panorama
and then stitching the photos together. I've done several partials,
but I really need to fasten the camera to the mast and then turn the
thing maybe 20 to 30 degrees for each shot.
I gotta take the mast out of the rotor, the rotor out of the tower,
then unbolt the tribander, hook up a come along, loosen the thrust
bearings and THEN let the mast down to the point where I can work on
the 6 meter antenna . The boom support came loose and now just lays
on top of the boom instead of holding it up. No problem for wind, but
if we get any ice it'll be all done.
As long as I have that much to do, I will probably lower the whole
works down to where I can replace the pig tails from four antenna
systems. I don't know if I'm going to leave the vertically polarized
144 and 440 arrays up, or just replace them with a "repeater" duo band
vertical and lower the top of the mast by 14 feet.
The only machine work was digging the holes for the guy anchors. It
took me two days to dig the one for the tower base and I had lost all
desire to dig three more about 2 1/2 times that size. The guy that
dug the holes "with a back hoe" shown in the photos, had a pole he
could fasten to the bucket on the front and he used that to carry the
guy anchor posts and set them in place. It was well worth the price.
<snip>
>Ya take the vertical antenna & mast load out with a thrust bearing
>either in the top plate or somewhere close to the top, run some loosly
>guided 2-3" EMT down the tower and . . . does a great job of knocking
>down the torsional start/braking/wind spikes throughout the system AND
>reduces the number of climbs. A second thrust brg just above the
>rotator is even better. I dunno where they come from.
This is pretty much the way mine is set up, except I use both 1 1/2
and 2 inch steel tube with 1/4 inch wall. Thrust bearing at the top
of the tower and one just above the rotor which is about 25 feet or so
down in the tower.
I didn't want to run the steel tubing all the way to the ground as
with this antenna load it would get pretty "springy".
The ROHN 3" thrust bearings are "about" $80 to $85 each. Maybe more
now. You can get them from quite a few distributors. Mine came from
Texas Towers. The tower itself was a closeout from Michigan Radio
down in MtClements MI.
Another "one of these days" I'd like to replace the steel tubing with
1/4 inch wall chrome molly. Tis expensive, but I'm not going to be
able to keep climbing forever. (although I'd kinda like to think so)
Zoran Brlecic
> All put up by hand...
Roger, what is the point in using a concrete form? I never understood
why it would be beneficial to purposely weaken the tower foundation just
to have a perfectly square concrete block that no one can see in the
ground.
73 .... WA7AA
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