Pulley
A device consisting of a rotating , grooved wheel between two side plates ; used to change the direction of pull in a line .
Ratcheting bollard |
A bollard-type lowering device equipped with a mechanism for lifting loads . |
Reaction force |
A force of equal magnitude exerted in the opposite direction to a force acting on a body . |
Resultant |
A single force equal to the sum of all forces acting on an object . |
Rigging |
A method of using ropes and hardware to remove large limbs or to take down trees . |
Rigging point
Risk
Risk assessment
Risk control ( risk control measures )
The place in the tree ( natural or false crotch ) that the load line passes through to control limb removal in rigging operations .
The likelihood that harm ( death , injury , illness or damage ) might occur when exposed to a hazard .
The process of deciding how dangerous or potentially severe a hazard is ; it combines magnitude of hazard , probability of occurrence and the likelihood of damage to result from such incident .
Actions taken to eliminate health and safety risks so far as is reasonably practicable , and if that is not possible , minimising them so far as is reasonably practicable . Eliminating a hazard will also eliminate any risks associated with that hazard .
Root flare The portion of a tree where the trunk flares out into the root system . Running anchor An anchor that is able to travel along a rope under load . Running end The end of a rope not in use . SAD
Safe Approach Distances describe the closest acceptable approach distances for tree workers and plant operating in the vicinity of electrical conductors .
Scarf A wedge-shaped cut forming the front of the hinge used in felling or limb removal . Speed-line A rigging line strung in such a way as to slide tree segments to the ground .
Spliced strength ( of rope or slings )
Strength of the rope when the splice is incorporated into the loaded system .
Standing part The inactive part of a rope , as opposed to the working end . Stick trick
Strategy of flexibility
Method of moving a rope over an obstacle by tying a stick into the rope mid-line and sliding the stick backwards and forwards over the obstacle .
The tendency of trees and tree parts to bend in the wind , reducing the surface area exposed to the wind , reducing the lever arm , and reducing the angle between the wind and the lever arm .
Stress ( in trees ) An unspecific but broadly adverse condition caused by factors such as drought , waterlogging , extreme temperatures , nutrient deficiency , attacks by pests or pathogens etc .
Stress ( mechanical ) The force applied to a point of a structure divided by the cross-sectional area of that point . Tag line
A pulling rope used to control the swing of a limb being removed ; a rope used to control the direction of fall of a tree or limb being removed .
Tensile strength Force at which a new piece of equipment or rope fails under a static load in testing . Tension
An internal stress in timber where the wood is being ‘ stretched apart ’ under load . Contrast with compression .
Thigmomorphogenesis |
The response by plants to mechanical stimulus , by alteration of growth pattern or habit . |
Throwline |
Light cordage used by arborists to set lines through unions high in the tree crown . |
Turn |
One wrap of a rope around an object . |
UHF |
Ultra-High Frequency device ; a direct broadcast communication device . |
Vector |
Graphical representation of quantities that have both a magnitude and a direction . |
Weight |
Force created by the action of the earth ( gravity ) on an object . |
Working load limit or WLL
The maximum recommended load a piece of equipment should experience when correctly configured during regular operations ; WLL can be calculated by tensile strength divided by design factor ; maximum load that should not be exceeded in a rope or rope assembly when performing its normal working function .
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