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[TowerTalk] Tram Questions and Observations

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Subject: [TowerTalk] Tram Questions and Observations
From: (Steve Sawyers n0yvy)
Date: Wed, 03 Sep 1997 10:52:03 -0500
Lee Buller wrote:
> This weekend, K0TQ and AB0S spent a whole lot of time (6 hours) on K0WA's
> tower replacing the top section, mast, rotor, etc.  They put up heavier
> stuff in preparation for a larger antenna.  I want to thank them publicly.
> Although the larger antenna was not ready to ascent to new heights we did
> put up a TA-33 until the other antenna (TH-6DXX) is rebuild and ready.
> To raise and lower the antenna, we used the tram system described on the
> reflector earlier this year.  My observations are as follows....
> ===>Do not use nylon rope.  It streaches way to much.  Should be a help rope
> like a climing robe that will not streach.
> ===>The sling has to be made just right or problems will occure.
> ===>A "tiller" needs to be installed to keep the antenna parallel to the
> tram line....but...what is the best way to do that?
> ===>The tram line rope needs to be tied at least 2 to e times higher than
> the sling height above the boom.
> Here are some of my questions.....
> Do you use a come-along to tension the tram line?

Yes - to the hitch on my pickup - currently changing over to a hand
winch with 30' of cable to let the trolley down (see below).

> Do you use 1/8" aircraft cable for the tram line so there is no flex?

I prefer 1/4 EHS guy cable - have lots of it.

> How do people make the sling on the boom?  We used norman hemp, tied in the
> middle and balanced.  

I made a two wheeled trolley using Unistrut and V-belt pulleys for
wheels. We call it Gondor the Condor.

The wheels are on top of the cable, and the UniStrut is cupped upward
with the trolley cable in the middle of the U. The trolley cable has to
be threaded through this Main Beam. The Main Beam (along the trolley
cable) is about 15 inches long. Bolted/welded to that is a Cross Arm
which is another piece of UniStrut about 3 feet long that we use to tie
to the antenna boom. Then straight up from that we have 12 inch member
that we use to lash the antenna's truss support to so we keep the
antenna elements parallel to the trolley line. We have a haul line run
from the nose of Gondor to a pulley on the tower so the ground crew does
all the work. We have a pull back line on the tail of the Gondor's Main
Beam to get the contraption back down the trolley line to get the next

The Cross Arm has lashing ropes and a cleat permanently attached to it
so a couple of wraps around the boom, two loops on the cleat and a half
hitch or two and you are done putting the antenna . Same thing at the
top of the tower to take it off.

The Cross Arm is about 6 inches from the nose of Gondor. That puts
enough weight on both pulleys to keep things straight, and gets the
antenna boom closer to the mast at the top of the tower.

The Cross Arm also has permanently attach tag lines at the end for
leveling. The tow, retrieve and tag lines are attach to the Cross Arm
with screw style chain repair links. The thought is nothing loose to

The point of building Gondor was to minimize the distance from the cable
to the antenna boom.

I am currently working on a design that will carry the antenna on top of
the trolley line. Then the trolley line attaches to the tower and not
the mast. We are planning on having a rigid arm hang below with a weight
to keep the center of gravity of the antenna/Gondor assembly below the
cable so it won't turtle on us. We want to put up W0EJ's stack of
monobanders as soon as he gets done refurbishing them. So have to get
back on that project.

>Do people you cable that is semi-perminantly installed?

We take them down.

> How long is the tiller and does it lead or follow the boom?  Does it have
> its own pully...or do you use a carabiner?  How tight is the tiller attached
> to the tram rope/ other you use a rope to attach the
> tiller to the tram line or do you use something rigid?
> Comments from the experts are needed.  The TH6 is waiting and the bands are
> getting pretty good.
> Thanks people....
> Lee Buller

de n0yvy steve

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