Author Topic: Knot Test Report: #1425A derived Riggers X bend (resistance to jamming) 2/3  (Read 2622 times)

agent_smith

  • Sr. Member
  • *****
  • Posts: 1470
Part 2 of 3

This is an addition to my test report in relation to #1425A derived Riggers X bend.

Image showing initial/threshold jamming state of 2 dissimilar abseil ropes at 10.0kN peak load.
Rope type: 11mm EN1891 type A
'Bluewater II' joined to 'Edelrid safety Super'.
Both ropes same age and same condition (excellent condition, hardly used, not stiff).

Riggers X bend was tied with S/S chirality/handedness (ie S twist to S twist).

Observational remarks:
The collar on the same side as the lever hoist jammed. I was able to loosen and untie the opposite collar (Bluewater rope) by hand. It 'appears' that one side of the end-to-end joining knot is experiencing greater tensional force which results in greater compression of the rope material. Although Newtons laws of physics would tell us otherwise - since force should be transmitted equally and simultaneously through both sides of the knot.
However since jamming always occurred on the same side as the lever hoist - a theory needs to be advanced to explain this phenomena.
I speculate that force is transmitted via the lever hoist side, and then permeates through the knot structure. It appears that tensional force is initially absorbed on one side and causing that side to crush/collapse at a rate slightly faster than the opposite side. In other words, there 'appears' to be a delay in force transmission.
Further testing needs to be carried out to examine this phenomena more closely and to develop a theory to explain the observations.

Result:
at 10kN  Jammed
« Last Edit: August 20, 2018, 07:16:08 AM by agent_smith »