Explanation:
The rigging line is typically the weakest component of a rigging system. The arborist only needs to make sure that the remaining equipment is within the working-load limit of the rigging line. Naturally, dividing the tensile strength by the design factor yields the working-load limit. The default design factor is often five.
Explanation:
To prevent excessive wear on a cable that is attached to anchoring hardware, use a thimble. In addition, the thimble can be utilized to enhance the bend radius when used with rope or to safeguard the cable's termination loop. A tool called a cable aid is used to wrap dead-end grips, open steel thimbles, and tighten lag screws. Lag hooks, sometimes called J-hooks, are open-eye, lag-threaded cable anchors. An example of a drill bit with an open spiral design is a ship auger. These are the tools that arborists use to drill holes for installing cables or bracing.
Explanation:
The rigging system with blocks has a 3:1 bend ratio if the pulley's diameter is three times larger than the rope's diameter. The diameter of a branch or sheave divided by the diameter of the rope encircling it is known as the bend ratio. A rigging system with blocks must have a minimum bend ratio of 4:1 to prevent damage to the rope and blocks caused by using a too-big rope for a particular pulley.
Explanation:
In a small tree, a lag-threaded rod would be adequate. Large trees, trees with soft wood, and decaying trees shouldn't be equipped with lag-threaded rods. Only machine-threaded rods will work for these trees. The lag-threaded rod is self-anchoring and has fewer threads per inch of the rod than the other type. The drilled hole should have a diameter that is one-sixteenth to one-eighth inch bigger than the rod when using machine-threaded rods.
Explanation:
Screw links are best suited for connectors that are rarely opened. An oblong metal ring with a spring-loaded gate that can open or close is called a carabiner. Carabiners are used in both static and dynamic rigging applications. A fitting with a U-shaped hole and a pin through it is called a clevis. A connecting device with a threaded closure mechanism is called a screw link. It fastens branches to rigging lines or other climbing and rigging components collectively.
Explanation:
Generally speaking, the first notch made when felling a tree should not be larger than one-third of the tree's diameter. Conversely, the hinge's length ought to be roughly four-fifths of the tree's diameter. The standard method for felling a tree is to make a notch and then a backcut. Open-face, Humboldt, and standard notches will all be used by arborists. An arborist can exert control over the tree for a longer duration if the notch is larger. Solid fiber provides a much superior hinge, therefore the arborist should strive to avoid placing the notches anywhere near deterioration or splits. Additionally, the arborist should refrain from cutting through the notch apex because doing so could damage the most crucial fibers that regulate the hinge.
Explanation:
The butt end of a branch that has been tip-tied will separate from the cut. The process of tying a line to the end of the limb that has to be cut off is known as tip-tying. The location of the rigging point has a significant impact on how far the branch will swing out. When tip-tying, climbers should use caution to steer clear of the area where the swinging limb is most likely to fall. In order to prevent the branch from hitting a target below the climber, the arborist may occasionally tip-tie the branch and have someone on the ground push it off the cut using a mechanical advantage.
Explanation:
Rigging is the process of taking down entire trees or removing limbs using ropes and other tools. Cutting a wedge into a tree trunk or branch and then making a reverse cut to finish the cut is known as notching. Branches are lowered to the earth during landing. A landing zone should be set up close to the tree by arborists. During removal, this is where big branches and leaves are supposed to land. When a moving load is suddenly stopped, shock-loading occurs, which is the sudden application of a dynamic force on the rope or rigging equipment.
Explanation:
A cow hitch should be used to secure the block to the tree while installing a false crotch. The arborist should tie two half hitches next to the bight in the cow hitch, close to the splice, after the knot has been tied. The working end of the sling is led around the stem, under the splice, and around again in the other direction to tie a cow hitch. Both the taut-line hitch and the Blake's hitch are popular climbing knots that are used to ascend and descend a climbing line. A girth hitch or English prussic knot in particular may occasionally be referred to as a "prussic hitch," which is a general word for any friction hitch.
Explanation:
For a huge branch growing parallel to the ground, propping would be appropriate. The act of placing strong structures between a branch and the ground is known as propping. When removing a branch is neither feasible nor wanted yet there is a risk of it falling and hitting something or the ground, this method is employed. There is no hard and fast rule when it comes to prop materials; successful props have been made out of concrete, metal, and wood. All that is required of the arborist is confirmation that the material selected will be robust enough to support the branch and that, once installed, the prop will require adequate upkeep.
Explanation:
One cycle for a rigging line is one raise and one drop in terms of rope. Cycle count is a unit of measurement for rigging line wear. In particular, a rope's lifespan can be expressed in terms of cycles till failure. Every usage cycle wears down the rope, regardless of how well it is maintained. Poorly maintained or unclean ropes will deteriorate much more quickly. Long before it hits its cycles-to-failure point, a rope can break.
