Tree work words: rigging
Slings, blocks, rings, lowering gear, hitches and load words used when a crew lowers limbs under control, each defined from TCI Magazine, OSHA, SafeWork NSW and WorkSafe New Zealand.
Checked against the sources at the bottom of this page on October 8, 2026. Rules, fees and pay change: the source has the last word.
Rigging means lowering limbs and tree sections under control instead of letting them drop. WorkSafe New Zealand's arboriculture code defines it as using ropes, slings and mechanical devices to lower limbs or sections of tree in a controlled manner. The words below are the ones those sources define, in the order a ground crew meets the gear.
Every meaning is written in our own words from the page named in its row. A word that none of those pages defines is not listed. The wider A to Z list is the tree work glossary.
Words and meanings
| Term | Meaning | Source |
|---|---|---|
| Rigging | Using ropes, slings and mechanical devices to gain a mechanical advantage and lower limbs or sections of tree in a controlled way that limits the impact on the surroundings, in WorkSafe New Zealand's arboriculture code. | WorkSafe NZ arboriculture code, definitions |
| Lowering, pulling or rigging line | A rope used in arborist operations to control the movement of a limb or tree, in the New Zealand code. | WorkSafe NZ arboriculture code, definitions |
| Lowering rope | A rope a climber uses to lower heavy branches or other parts of the tree, in the New South Wales glossary. The glossary adds that it may also serve as a tool line. | SafeWork NSW tree work code, glossary |
| Lowering device | In the New South Wales glossary, an instrument attached to the base of a tree during rigging and used to take wraps with the lowering rope. | SafeWork NSW tree work code, glossary |
| Sling | The strap or rope used to hang a rigging ring, block or lowering device from the tree. TCI Magazine names four main configurations: dead-eye, multi-sling, whoopie and loopie. | Tree Care Industry Magazine article on rigging tools for ground technicians |
| Dead-eye sling | A sling with a spliced eye at one end and a plain finished end at the other, in TCI Magazine. The magazine says that lets the user tie it on with a range of knots and hitches. | Tree Care Industry Magazine article on rigging tools for ground technicians |
| Multi-sling | A sling with many attachment holes for a ring or block, in TCI Magazine. The magazine lists quick setups as a benefit and the difficulty of a tight setup as a limit. | Tree Care Industry Magazine article on rigging tools for ground technicians |
| Whoopie sling | A sling with two eyes, one of which can be adjusted through a bury, a section of material inside the sling that behaves like a finger trap, in TCI Magazine. | Tree Care Industry Magazine article on rigging tools for ground technicians |
| Loopie sling | The same design as the whoopie sling, but one large round loop whose size adjusts, in TCI Magazine. | Tree Care Industry Magazine article on rigging tools for ground technicians |
| Flop | TCI Magazine's word for a rigging ring or block that is not snug against the sling and the material it is secured to. | Tree Care Industry Magazine article on rigging tools for ground technicians |
| Rigging ring | A smooth ring used aloft. TCI Magazine says it creates friction in the way a natural union in a tree does, and that it lets the worker spread load and friction through the system. | Tree Care Industry Magazine article on rigging tools for ground technicians |
| Rigging block (impact block) | TCI Magazine says a block differs from a pulley because a pulley is designed for a load that sits under it, while a block lets the user place it below the load and catch the load as it is lowered. It describes a double-sheave design with rounded soft edges. | Tree Care Industry Magazine article on rigging tools for ground technicians |
| Micro pulley | A small lightweight pulley, in the New Zealand code. | WorkSafe NZ arboriculture code, definitions |
| Friction device | A metal device that controls friction on a line, in the New Zealand code. In rigging, TCI Magazine places a bollard-type lowering device at ground level and a rigging ring aloft. | WorkSafe NZ arboriculture code, definitions; Tree Care Industry Magazine article on rigging tools for ground technicians |
| Basket hitch | In OSHA's slings standard, a way of using a sling in which it runs beneath the load and both of its ends are carried on the hook or on one master link. | OSHA slings standard 1910.184, definitions |
| Choker hitch | In OSHA's slings standard, a way of using a sling in which one end goes under the load and back through the fitting or eye at the sling's other end. | OSHA slings standard 1910.184, definitions |
| Angle of loading | How far a sling leg leans, measured from horizontal or from vertical, in OSHA's slings standard. The standard treats five degrees or less from vertical as vertical. | OSHA slings standard 1910.184, definitions |
| Choker (logging) | In OSHA's logging standard, a sling that wraps the end of a log for yarding. It goes around the load, back through a fitting at its far end, and that end is then hooked to the machine that pulls. | OSHA logging standard 1910.266, definitions and felling rules |
| Rated capacity, working load limit | In OSHA's slings standard, the heaviest working load that section allows. TCI Magazine uses working load limit for the rating of a block, ring or sling, and says ratings of linked parts are matched. | OSHA slings standard 1910.184, definitions; Tree Care Industry Magazine article on rigging tools for ground technicians |
| Safe working load | The safe working load of a piece of equipment as the maker specifies it, in the New Zealand code. | WorkSafe NZ arboriculture code, definitions |
| Shock load | The dynamic load placed on a rope or rigging apparatus when a moving object or a falling person is stopped, in the New South Wales glossary. TCI Magazine links the risk to load locked off at the ground friction device. | SafeWork NSW tree work code, glossary; Tree Care Industry Magazine article on rigging tools for ground technicians |
| Tool lanyard, tool strop | Rope or webbing that attaches the climber's tools to the harness, with a tear-away, in the New South Wales glossary. The New Zealand code defines a tool strop as a short line securing tools aloft. | SafeWork NSW tree work code, glossary; WorkSafe NZ arboriculture code, definitions |
Reading these sources
The sling and block entries come from a TCI Magazine article written for ground technicians. TCI Magazine is the Tree Care Industry Association's trade magazine, so its entries describe how the trade uses the words and are not a standard. Brand names that appear in the article are left out here.
The basket hitch, choker hitch, angle of loading and rated capacity entries come from OSHA's standard for slings. That standard covers slings in general industry material handling, not tree work in particular, so the rows say what OSHA defines and do not claim a tree-work reading. The lowering device, lowering rope and shock load entries come from the New South Wales tree work code of practice, and the rigging, pulling line and pulley entries from the New Zealand arboriculture code.
Words such as load line, tag line and speed line, and the gear around them, are in rigging words by kind. Climbing-side words are in tree work words: climbing.
Contains material from the SafeWork NSW Tree work code of practice, which SafeWork NSW publishes under a Creative Commons Attribution 4.0 licence. Contains material from WorkSafe New Zealand publications. The wording above is ours.
Sources
- WorkSafe New Zealand, Safety and Health in Arboriculture approved code, definitions, read October 8, 2026
- SafeWork NSW, Tree work code of practice, appendix A glossary, read October 8, 2026
- Tree Care Industry Magazine, Rigging tools: an overview for ground technicians, read October 8, 2026
- OSHA, 29 CFR 1910.184 Slings, definitions, read October 8, 2026
- OSHA, 29 CFR 1910.266 Logging operations, definitions and felling rules, read October 8, 2026