Hi Al,
I've trammed three 4-el SteppIRs and a 165 lb 2D-40A up my 110' Rohn 55
tower, so "been there, done that."
Your setup for the tram and sling sound good. The tiller is an absolute
must. The large SteppIR beams are not very well balanced, and it's tough to
rig the sling to get perfect balance in all planes. For my three SteppIRs, I
used a tiller off the back of the beam with a pilot line to the ground. By
tugging on the line I could more-or-less keep the beam from rotating and was
able to vary the attack angle a bit. But results varied and sometimes I
couldn't exert enough force to control the beam. We'd have to tram it back
down and reset the sling for better balance and attack angle. Also, this
setup didn't prevent the boom from turning in the sling, which had a
tendency to happen. Instead of using a standard cinched-loop strap, I had to
use hose clamp to hold the straps in place. I wasn't comfortable with the
notion of the steel hose clamps digging into the straps.
I figured the ground-managed tiller wouldn't work for my 165 lb Cal-AV
2D-40A, so I went with a different arrangement that worked a whole lot
better. I considered a tiller off the back with a pulley riding the tram
line. Many have used this setup successfully, but I was concerned that the
pulley would allow some side-to-side motion (i.e., crabbing), and might not
work well to keep the boom from turning in the sling and pitching the front
elements down (I figured the pulley would do a good job keeping the beam
from pitching in the opposite direction.)
At the suggestion of a TowerTalk participant, I ended up using a tiller off
the front of the boom -- i.e., facing the tower. The tiller is made of
heavy-duty angle-aluminum. A couple of holes allow it to be fixed the boom
with a U-bolt. A hole in the other end accepts a carabiner, which in turn is
attached to the haul line (actually, for quick-disconnect, I used two
carabiners -- one on the haul line and one on the tiller.) It's easy to set
the attack angle by varying the angle of the tiller to the boom. The beauty
of the front tiller is that the force of the haul line won't let the tiller
move with respect to the tram line. This keeps the antenna from crabbing,
rotating, tilting etc. It worked very well.
As for clearing the top plate, I like Dave's suggestion of pulling back
toward the back stay anchor point if you can find an angle that will clear
the top plate.
Another thought is to mount the SteppIR mast plate to the mast and attach
the pulley to an eye bolt stuck through one of the holes on the edge of the
plate. The mast plate is quite large and may give you enough clearance to
get over the top plate. If not, a short piece of 2" galvanized pipe will
allow you to mount the pulley out beyond the mast plate. You're not exactly
pulling sideways on the mast, but the force won't be straight down, either.
If you have a steel mast, I believe it will be able to handle the forces
involved.
Finally, you can do it the way I did. My three SteppIRs are mounted on TIC
rings below the top of the tower, but the Cal-AV is mounted on a short 1/4"
aluminum wall mast directly above the thrust bearing in the top plate. I
didn't feel at all comfortable putting any sideways tram/haul forces on the
aluminum mast. So, I attached the tram line to the tower just below the top
plate. I used a pair of short sling straps around each leg, connected with a
carabiner through the loops. The tram line was connected to the carabiner
(again, I used a second carabiner on the tram line for quick disconnect.)
The haul-line pulley was attached to the tower just below the tram line, in
a similar manner.
--> Note that my method won't work if your top guys are attached to the top
plate. The top guys on my tower are 15' below the top plate. In effect, I'm
using an extra 10' tower section instead of a 10' longer mast. Rohn 55 is
beefy enough to deal with that. I believe my tramming method will work if
your guys are at least 5' below the top plate, which is the standard Rohn
configuration.
Here's the method: When the antenna reached the haul line pulley, we slowly
let the slack off the tram line so that the beam would fall gently against
the face of the tower. At this point, the antenna was being held up by the
haul line only (attached to the tiller.) I climbed up and removed the tram
pulley (actually a trolley) from the tram line and sling. Then I
disconnected the tram line from the tower, moved the tram line under the
antenna, and clipped it to a tower rung with its carabiner. Obviously, with
the method I used, the tram line has to be moved below the antenna in order
to haul the antenna up to the mast. Previously, I had attached a come-along
to the top of the mast, which extends about five feet above the top of the
tower. I attached the come-along cable to the sling, tensioned the
come-along so it was carrying the weight of the antenna, disconnected the
haul line and removed the tiller The haul line was moved out of the way and
clipped to the tower, as was the tiller. I then used the come-along to haul
the antenna up and over the top plate to the mast. I was a little worried
that the antenna would get hung up on the lip of the top plate, but this
didn't end up being a problem -- I was able to push the antenna out a bit
and crank the come-along to get it over. If two people are on the tower,
this would be even easier. Or, if you're working alone, you can use a short
section of pipe fixed to the mast with a steel plate to get the come-along
out over the top plate. From that point, it was relatively simple to haul
the antenna up the rest of the way to the boom-to-mast plate, which was
already mounted on the mast.
Hope this helps.
73, Dick WC1M
> -----Original Message-----
> From: David Robbins K1TTT [mailto:k1ttt@arrl.net]
> Sent: Sunday, November 23, 2008 7:17 AM
> To: 'Al, N6TA'; towertalk@contesting.com
> Subject: Re: [TowerTalk] Tramming help sought
>
> Well, either put something smooth on the edge of the top plate to let
> the
> rope slide easier, or pull back toward the back stay anchor point.
>
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt@arrl.net
> web: http://www.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
>
>
> > -----Original Message-----
> > From: Al, N6TA [mailto:n6ta@yahoo.com]
> > Sent: Sunday, November 23, 2008 04:54
> > To: towertalk@contesting.com
> > Subject: [TowerTalk] Tramming help sought
> >
> > I won't bore the readers with the usual retread questions. Already
> did
> > the reading etc. and lowered the old beam a month ago. This is one
> on how
> > to rig the haul line to pull up the 110 lb SteppIr yagi.
> >
> > The tram line is to be rigged about 3 feet above the top on the Rohn
> 45
> > tower which has a flat top plate. The boom will be mounted right
> above
> > the top plate. The tram line is continuous in that it goes thru a
> pulley
> > and down to a 'back stay point'. Trying to allow the tram line some
> > ability to move but direct most of the force down the mast to the
> rotor.
> >
> > The beam will be hung from a sling that connects a pulley to the
> tram
> > line. The boom will hang about 18 inches below the tram line. A
> > tiller/torque arm will be attached 'behind' the boom, keeping the
> boom
> > from rotating in two axes.
> > The haul line is half inch polyester double braid and will be tied
> to the
> > boom close to the CG point. The bracket that holds the tram line
> above
> > the tower top has a place for a pulley to be mounted for the haul
> line,
> > probably attached with a snap link or shackle. The question I have
> is how
> > to rig the haul line's pulley such that I can pull straight down
> and not
> > have interference with the tower's top plate. The bracket for the
> pulley
> > is about 3 inches out from the mast and the tower needs about 9
> inches
> > clearance from the mast to go straight down without rubbing on the
> edge of
> > the top plate. I fear way too much friction if I allow this. I
> lowered
> > the prior beam this way and used the friction to advantage but do
> not want
> > such issues when pulling up the new beam.
> > If I rig the haul line pulley ( a CMI 2.375 inch 95% eff. rescue
> type)
> > such that it is hanging out far enough to clear the top plate, I end
> up
> > pulling sideways on the mast.
> >
> > There must be a standard practice here but I have not yet read any
> > postings about this detail. I usually just 'go for it' and keep the
> > fingers crossed. I have way too many PhDs in the School of Hard
> Knocks
> > and prefer to not get another....
> >
> > If I can pull the beam up as far as it can get, to the haul line
> pulley, I
> > plan to relax the tram line and let it settle the boom down where it
> will
> > rest on the top plate until I can use other means to raise it the 6
> inches
> > to the boom to mast plate.
> > Willing to call to talk about it.
> >
> > Tnx in advance.
> > Al
> > N6TA
> >
> > Yeah, I'm missing the CW test due to delay in getting this up.
> >
> >
> >
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
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