It's all about the diameter of the wire under test and the
amount of deflection when the mechanics of the Loos presses
on that wire to deflect it between two points on the instrument. The
amount of
deflection is indicated on the Loos dial which is calibrated to read
tension.
Different diameters of flexible cable will cause the Loos to read
differently
even if the tension is the same. So the Loos, and similar gages,
should be calibrated for the cable to be tested. Note that the usual
guy wire like 3/16" EHS will read differently if a tension gage is
rotated about the axis of the wire. That's because the wire isn't
perfectly round due to the standing.
Charlie, N0TT
On Sun, 25 Jul 2021 13:04:06 -0700 Ken Alker <ka6ken@alker.net> writes:
> If my conclusions are correct, the chart appears to be based upon the
>
> breaking strength of a different type of wire than one would use for
> a
> tower. The chart appears to be based upon stainless steel cable
> (for
> sailboats) rather than zinc coated cable (for towers). The SS cable
> has a
> higher breaking strength, hence, using the Loos would mean one would
>
> over-tention the guys on a tower if using the % scale, rather than
> the LBS
> scale.
>
> --On Sunday, July 25, 2021 3:49 PM -0400 john@kk9a.com wrote:
>
> > Why are you concerned with the Loos gauge's breaking strength
> chart? I
> > just use the table to set the guy wires to the recommended
> tension
> > (usually 10% of its breaking strength).
> >
> > John KK9A
> >
> >
> >
> > Ken Alker ka6ken wrote:
> >
> > I'm new to this, but did a lot of research and found that the Loos
> PT2
> > appears to be calibrated for wire with a breaking strength of
> 4545-5000
> > lbs, while the Rohn 3/16EHS500 wire has a breaking strength of
> 3990 lbs.
> > I assume, based on specs on various types of wire rope found at
> > <http://www.wcwr.com/catalog/webcat.pdf>, that the Loos PT2 is
> calibrated
> > more for 1x19 Stainless Steel type 304 wire rope used for
> sailboat
> > rigging (4700 lbs) rather than zinc coated 3/16EHS500 (3990 lbs).
> Here
> > is my math based upon the chart found on the Loos gauge (from the
> web
> > site quoted by Tim, below):
> >
> > LBS % LBS/%
> > ---- -- -----
> > 240 5 4800
> > 300 6 5000
> > 420 9 4666
> > 500 11 4545
> > 640 14 4571
> > 840 18 4666
> > 1030 22 4681
> > 1240 26 4769
> >
> > In conclusion, perhaps one should pay more attention to the "LBS
> TENSION"
> > portion of the Loos chart than the "% BREAK STRENGTH" if using the
> Loos
> > for 3/16" EHS (assuming it deflects in the same way that the
> sailboat
> > wire rope deflects), or one may overtension their guys.
> (Although,
> > perhaps the error when tensioning to 10% of breaking strength
> when
> > tensioning to 400lbs, or 600lbs in the case of Phillstran, isn't
> big
> > enough to worry about?)
> >
> > Even then, however, I'm very curious as to why the Loos numbers
> are all
> > over the map (4545-5000) rather than consistent at one breaking
> strength;
> > it is not just rounding error since their "LBS TENSION" appears to
> be
> > +-10 lbs.
> >
> > Ken, KA6KEN
> >
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
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> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
>
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