[TowerTalk] Tramming

Tue Aug 17 19:56:35 EDT 2004

> Yes, it would be nice to use Phillystran or other Kevlar products.  But
> there are two real big negatives that will keep most from doing it:
>
> 1. Expense - 1/4 EHS equivalent is 6700, $1.29 per foot, plus $12 each for
> big grips (cannot use clamps);

Except for a tram, unless hauling something really heavy 4400 is plenty 
strong with a 4,000# plus rating and it was around 60 to 70 cents a foot.

I use a friction clamp, the same thing I use to pretension the guys.  It's 
just a pair of grips that pivot on a metal plate. They only grip about 2 
inches worth, but work like a charm.

Yes, you can use clamps for a temporary hook up, but I prefer something that 
grips at least an inch wide.  These are also available commercially, but 
they are also expensive.  It's also easy to make good safe clamps out of 
aluminum sheet/stock  IF you have the tools.  The dimensions aren't 
critical, but 1/2 inch stock is convenient.  Cut out blocks 1 1/2 X 4 
inches. Mark a line down the center lengthwise.  Drill for at least two and 
preferably 3 screws.  Drill the first holes all the way through of the 
proper size for threading, or just drill out to use bolts.
Then drill one block with holes that are a slip fit to the screws/bolts to 
be used.
Clamp the blocks together when drilling so there is no misalignment.

With the block bolted together drill two holes lengthwise mid way between 
the centerline and edge.  Finish drilling this hole around 1/16" smaller 
than the OD of the Kevlar cable.

Use two blocks with the cable looped through the second as a safety 
just-in-case to prevent any slippage.

I'd use plain old wire rope before resorting to EHS for a tram line.  It's 
much more flexible and 3/16" to 1/4 inch is *relatively* easy to handle.
>
> 2. Danger - Kevlar can be cut with a knife, or an unlucky encounter with 
> an
> old pulley rim.
>
Yes, it can be cut, but my last experience with *trying* to cut 6700 was to 
finally give up and get a cable cutter. It is easily damaged, but if the 
jacket takes a nick while being used as a tram line it really isn't going to 
hurt anything.  OTOH if a guy takes a nick it becomes open to the elements 
and eventual weakening.

> My 500 foot roll of 1/4 EHS came delivered in a steel banded coil of about
> 2.5 feet diameter.  I can roll it back to a 3 foot coil without a lot of
> trouble and use tape or twine to hold together.  Seems a small task 
> compared
> to the cost/risk of Kevlar.

Yah, but I can pick up a 500 foot roll of 6700 with one hand. Matter of fact 
I have a coil of 1/4" EHS that has never been unrolled since I purchased it. 
(The dealer had a coil laying in the corner) I'm not sure just how much is 
there.  What's it weigh per 100 feet?  I'd gladly part with it for a good 
price as I'll never use the stuff.  Offer enough and I'll throw in a Henry 
2K4 with a brand new set of tubes and a spare pair of Eimac 3-500s.  New 
Peter Dahl plate transformer.  Works well, but relays are noisy like all the 
early Henrys.  I was using it out in the shop with my Icom 751A, but sold 
the 751A.

Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair (S# CD-2)
www.rogerhalstead.com
>
> Keith NM5G
>
> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of Tower (K8RI)
> Sent: Tuesday, August 17, 2004 3:32 PM
> To: Jim Idelson; TowerTalk Post
> Subject: Re: [TowerTalk] Tramming
>
> My preference would be one of the Kevlar based cables which is what I use
> for guy lines.
>
> Although much easier to handle and store, lighter weight, and though they
> are much easier to damage then EHS.  That means the tram needs to have 
> good,
> smooth pulleys, and no sharp edges.  The ends also need to be sealed from
> moisture.  Due to their light weight and strength they have very little
> catenary.  This really shows when you run a tram up one carrying a heavy
> weight as there will be a pronounced dip at the tram the size of which
> depends on the weight and cable tension.
>
> Even taking all that into consideration, I still prefer the Kevlar cables.
>
>
> Roger Halstead (K8RI, EN73 & ARRL Life Member) N833R, World's Oldest
> Debonair (S# CD-2) www.rogerhalstead.com
>
>> Thanks for all the responses. Looks like EHS is the way to go. I like
>> the idea of using Big Grips on the ends so that the terminations are
>> adjustable and so the pulley can travel right up to the mast. The only
>> thing I don't like about this solution is the difficulty in storage.
>> I'd prefer a more flexible material that can be rolled more easily
>> into a smaller roll.
>>
>> 73,
>>
>> Jim Idelson K1IR
>> email    k1ir at designet.com
>> web    http://www.designet.com/k1ir
>>
>> _______________________________________________
>>
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>>
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>
>
> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
> any
> questions and ask for Sherman, W2FLA.
>
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> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless 
> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
> any questions and ask for Sherman, W2FLA.
>
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