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Arboriculture & Urban Forestry Online
Volume 38, Issue 1 — January 2012

Breaking Load of Hitches and Ropes Used in Rigging    (View PDF)

Brian Kane

Abstract: The incorporation of hardware like blocks into the rigging system has prompted a change in the types of ropes used as slings to attach blocks to trees. Since large forces can be generated while rigging trees, it is important to determine the breaking load of hitches used to attach a sling to a tree or the rigging rope to a piece of wood. Breaking load and specific strength (the ratio of breaking strength to linear density of the rope) were measured for four common hitches and seven ropes often used in arboricultural rigging. Hitches were tied around a utility pole to simulate field conditions, and tested with a gradually increasing load. Breaking load was similar between all hitches, but varied widely among ropes, while specific strength differed between ropes and hitches. Tying hitches around the utility pole mimicked the arboricultural application of hitches and ropes, but the static application of the load, which did not reflect dynamic loads often generated during rigging, was an important limitation.

Keywords: Breaking Load; Hitch; Rigging; Rope; Specific Strength.

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