Ahhh, for that junction a fellow TT member showed me a super simple &
elegant way to form a single loop in the rope and slip it through the
carabiner then pull it back down over the top & on the opposite side.
Kinda hard to put in words but it involved no cuts or hard knots in the
rope. Best of all it can be removed in 5 seconds if need be.
Also not mentioned, once the loop & pulley are hoisted up in the air I
will use a simple loop in the opposite rope to attach to a 1/4"
preformed "S" hook so the ropes cannot move up or down over time.
Gedas, W8BYA
Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 12/9/2019 1:44 PM, Edward Mccann wrote:
And finally, what knot did you use to secure the carabiner into the loop?
Sent from my iPhone
On Dec 9, 2019, at 7:56 AM, Gedas <w8bya@mchsi.com> wrote:
Grant TU for the very useful write-up and description. Yesterday before solid rain and
below freezing temps set in today my wife and I managed to put everything in place and
raised up both towers. Each now has my 2x4 with pulleys arrangement attached &
threaded and I really like the way it turned out. Running up the loop with attached SS
Carabiner clips up & down worked out so well.
I provided a couple of URL's showing the 99% finished setup. Images do not show the SS
pulleys attached to those clips. The images may look a little confusing but I tilt over my
70' Universal towers (with 22' mast) using a system I designed and have been using for over
35 years. The black poles are a pair of 6"x6"x18' PT timbers bolted together and
set into 7' deep concrete (same as the HD tower bases). A double pulley system and geared
winch allows me to tilt up & down the towers in about 10 minutes since I do not climb.
The images show I used a simple square knot to join the rope ends but these
will be replaced with a double fisherman's knot in the next day or so. Thank
you again to everyone who helped out and provided input.
https://drive.google.com/open?id=1VLLuLA9e7lridHe3BgwfX34fbRPZeKti
https://drive.google.com/open?id=12aRNdm-8hnw31shSPDEoO-Lz7QGm4J-R
https://drive.google.com/open?id=1hn2NeCGb5lYBqMVq4dqbvomNpWM0836T
Gedas, W8BYA
Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 12/1/2019 11:40 PM, Grant Saviers wrote:
I looked at your 2x4's with pulleys jpgs. If rope strength is a concern, then
consider that going around a sheave (pulley) significantly compromises strength
in two ways. I thought a comment would be appropriate given the discussion
about knot strength.
The rope fibers are compressed inside and stretched outside in the sheave wrap
so the strength can be degraded 50% or more. The pulleys you appear have a
tiny radius. Repeated passage is cumulative for damage. Check rope specs for
the recommended sizes.
https://www.mazzellacompanies.com/portals/0/Images/Page206_3.png (might be for
wire rope, same problem, bigger loads and life safety = bigger concern)
The second problem is there is a lot of friction in the pulleys. I've seen
tests for hardware store ones where the output tension is only half of the
input tension. I use a good sailing block, the best have polymer ball
bearings. It's amazing the difference low friction makes.
Sailboat pulleys are also made to minimize chafe, so if the load moves or the
rope stretches in the wind you will be much happier in the long run spending
$20 for the good ones. I figure a tower climb costs much more than $20 if the
rope breaks or the pulley fails. Harken, Lewmar, Ronstan, are all great. Here
is the one I am currently using
https://www.amazon.com/Ronstan-Ball-Bearing-Orbit-Block/dp/B002NSSCF2/ref=sr_1_6?dchild=1&hvadid=3527191554&hvbmt=bp&hvdev=c&hvqmt=p&keywords=ronstan&qid=1575260910&sr=8-6
Also, I went back to your original post to understand the goal. You mention 30# load. The actual load in a rope pulled from the side is greatly affected by the angle the rope makes with the a line between the ends. i.e. at halfway actual rope tension is load/sine(angle). That means at zero degrees the tension multiplier is infinite for a load 50% between the support points. Obviously, that never happens since the rope stretches or something fails. When your hoist point gets to the top pulley then that pulley will take all the load and the other line part can be slack, so not a problem. Be aware that when hoisting,there might be a larger tension then expected halfway up if the hoist is a tight loop. And the loop force on the supports is twice the tension. So a better solution is to put a lot of slack in the hoist loop. I always use a loop through my permanent sailboat blocks in trees, just to never lose an end, but they have a lot of slack, also to reach the antenna on the
ground partway out.
Grant KZ1W
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