I would concur with John. I installed 3 AB Chance anchors a couple
of months ago and would never think of installing them myself.
After very carefull consideration, I had decided on a particular type
of screw attachment, and after inspection by a qualified installer,
it was decided that a different type was needed for my soil type.
They also require a digger derrick for proper installation.
That being said, once properly installed, that should last a lifetime
or much longer.
GL!
73,
Larry K4AB
On 6/25/14, John Langdon <jlangdon1@austin.rr.com> wrote:
> The Chance anchors are widely used, but are usually put in by one of their
> installers, who sample the soil and twist the anchors in and have the
> equipment to confirm the calculated holding strength in your soil. I would
> not consider installing them yourself.
>
> 73 John N5CQ
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
> Byron
> Tatum
> Sent: Wednesday, June 25, 2014 1:25 PM
> To: TowerTalk@contesting.com
> Subject: [TowerTalk] Screw Anchor "Tripleye" Heads
>
> Hello-
> ( Preface: I will be the first to admit that I do not wish to get outside
> of
> any manufacturer ratings and make improper substitutions. This post is only
> to receive comment and to try and learn something that I may be overlooking
> or have not thought about.)
> I am considering using some of the Hubbell (AB Chance) extra heavy duty
> helical anchors for a 120' tower. These are screw type anchors with a 14"
> auger and 1-1/4" rod 8' long, grade A-575 (select forged) steel with the
> forged "tripleye" end connection. I am studying using them in concrete guy
> anchors,and how to interface between the "tripleye" end and 3 guy
> wires terminations ( 5/8" turnbuckles). I will be the first to say "why not
> just use the Rohn concrete guy anchors" but the particular ones I want
> (GAC5655top with 1-1/4" rod grade A-572-50 steel) will cost almost $1000.00
> for a set of 3 shipped to me. The AB Chance anchors with 1-1/4" rods are of
> comparable low-alloy high strength steel, hot dipped galvanized and cost
> from 61.00 (10" helix) to 99.00 (14" helix) and are available locally.
> To interface to the set of 3 guy wires I am considering using one
> of the Crosby high strength alloy shackles, but it appears to me from
> studying the tripleye drawings that to attach a shackle of any size to the
> tripleye I will need to put the bolt of the shackle through the tripleye.
> It
> would seem better to have the curved part (bow) of the shackle engaging the
> tripleye, but it appears from drawings that a 5/8", possibly 3/4", shackle
> may be the largest one I could get on in this fashion. If I went this route
> I could install an equalizer plate on the 0.88" diam bolt of the 3/4"
> shackle, if it will fit on tripleye. A 3/4" alloy Crosby shackle would
> provide a 15,400# working load, proofed to 2 x working load, ultimate
> strength of 4.5 times working load.
> To use a larger shackle, from studying drawings of tripleye, it
> appears I
> could get a bolt of about maximum 1-1/4" diam through it, so that would
> alloy me to use a maximum of 1-1/8" shackle (over 30,000# working load).
> The
> anchor manuf (Hubbell) actually supplies an extension rod that has a clevis
> end with a 1" diam bolt that attaches to the tripleye. Although this is of
> no use to me, it shows that it is acceptable to pass a bolt through the
> tripleye and retain strength ratings. I was trying to avoid removing the
> tripleye as it is forged onto the rod and the manuf states it is stronger
> than the rod itself. Is it acceptable to use a large shackle as an
> "equalizer", with smaller shackles, of appropriate rating, connecting the 3
> individual turnbuckles to the larger shackle? It appears this could be done
> without creating any off-angle, side or other such loads that can
> de-rate on
> any part of the system. Crosby states in their specs that single-point
> loads on the bow of the shackle are acceptable to full ratings. Another
> question is in order to do this the tripleye would need to be oriented
> horizontally (normally it would be oriented vertically), in order for the
> bow of the shackle to be oriented vertically. Someone may say that by the
> time you add up the cost of shackles the cost savings may not be so great,
> however I have a large collection of shackles here in my tower hardware
> inventory.
> I have thought about attaching a set of equalizer plates to the
> tripleye using a large high strength bolt, such as 1-1/4", with each
> equalizer plate half being 1/4" steel. What I do not like about this is the
> large size of the tripleye, requiring a spacing of well over 2" of the
> equalizer plate halves. This may not be an issue if I use large enough high
> strength bolts in the equalizer plates to attach turnbuckle eyes to, and
> spacers to keep the turnbuckles centered over bolts.
> I studied some installations of towers well over 100' tall using the
> larger helical anchors holding in soil (as depicted in pictures on
> internet), with various types of shackles attached to tripleye, so
> that prompted me to study this.
> Thank you, Byron WA5THJ
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