Rigging words: what the crew calls what

Rigging is how a crew lowers limbs and tree sections under control instead of letting them drop. The New Zealand code defines it as using ropes, slings and mechanical devices to lower limbs or sections of tree in a controlled manner. This page lists the words. The few figures in it are quoted from a named code or maker and are not instructions.

Most meanings below come from two TCI Magazine articles on rigging gear, a 1989 paper in Arboriculture and Urban Forestry, the New South Wales tree work code of practice, US and UK rules, and the New Zealand code. The 1989 paper is old, so the entries that rely on it say so. For the wider list of tree-work words, see the A to Z glossary.

Same rope, different name

Rigging ropes get different names by country and by crew. Each row is what the named source says.

The word	What it means there	Source
Load line	The rope that carries the weight of the piece	US, 1989 paper
Tag line	A line that controls swing	US, 1989 paper
Tag line	A separate rope used while lowering to control where the load lands	Australia, NSW code
Lowering rope	A rope the climber uses to lower heavy branches. It may also be a tool line	Australia, NSW code
Pulling, lowering or rigging line	One rope used to control the movement of a limb or tree	New Zealand code
Strop or tag line	Named together in the New Zealand rule on rope strength	New Zealand code

Gear

Block: a rigging pulley that lets the user place the tool below the load and catch it while it is lowered. TCI Magazine says a pulley is designed for the load to sit under it. Rigging blocks are often called impact blocks and have a double-sheave design.
Micro pulley: a small lightweight pulley (New Zealand code).
Sling: the strap or rope used to hang a block, ring or lowering device from the tree. The four main kinds in TCI Magazine are below.
Dead-eye sling: a sling with a spliced eye at one end and a plain finished end at the other.
Multi-sling: a sling with several attachment holes for a ring or block.
Whoopie sling: a double-eye sling where one eye adjusts, because of a "bury" inside the sling that works like a finger trap.
Loopie sling: the same design as the whoopie, but one large round loop whose size adjusts.
Rigging ring: a smooth ring used aloft. TCI Magazine says it creates friction where the rope runs through it, much as a natural union would.
Anchor sling, friction saver, cambium saver: the New South Wales code says a friction saver or anchor sling is used to reduce friction at an anchor. The New Zealand code says friction saver and cambium saver are the same thing.
Lowering device: a friction device mounted near the base of the tree that the lowering rope runs through or around. A bollard-type device creates friction at ground level. The New South Wales code defines it as an instrument attached to the base of a tree in rigging, used to take wraps with the lowering rope.
Bollard: a round object to take wraps of rope against. The 1989 paper borrows the word from naval use and gives a pipe bumper as an example.
Friction device: a metal device that controls friction on a line (New Zealand code).
Carabiner (karabiner): a connector with a gate. The New Zealand code lists karabiner and points to carabiner. The UK HSE lists karabiners as lifting equipment in arboriculture. The New Zealand code says an auto-locking one closes into the locked position by itself and needs at least three distinct movements to open. The New South Wales code says a karabiner or shackle should not be used in place of a pulley.
Tool strop, tool lanyard: a short line that secures tools aloft (New Zealand code). The New South Wales code says a tool lanyard or strop attaches the climber's tools to the harness and should incorporate a tear-away.
Eye splice: an eye made in the end of a rope by splicing. TCI Magazine says "spliced eye". The 1989 paper says "eye-spliced rope".
Come-along: a hand tool the 1989 paper uses to adjust tension on a speed-line or to hold back a leaning trunk.
Ground anchor: something on the ground a speed-line is tied to when nothing else is handy (1989 paper).

Ropes and lines

Load line: in the 1989 paper, the rope that carries the weight of the piece.
Tag line: a line that controls the swing of a piece. The 1989 paper says load lines carry the weight and tag lines control swing. The New South Wales code says workers should use a separate rope, the tag line, during lowering to give more control over where the load lands.
Lowering rope: in the New South Wales code, a rope the climber uses for lowering heavy branches or other parts of the tree, which may also be used as a tool line.
Bull rope: a rope the 1989 paper names next to the tag line. It says a throw line sets either one in places that are hard to reach. The paper does not define the term, so crews may mean different ropes by it.
Pull line, lowering line, rigging line: the New Zealand code lists these together as a rope used to control the movement of a limb or tree.
Throw line: a light line used to set a tag line or bull rope in a hard-to-reach place (1989 paper). The New Zealand code describes a throw bag on a light line.
Climbing line: the rope the climber is attached to, not a rigging rope. The New Zealand code says climbing lines are built for tree climbing with a breaking strain of 22 kN when new.

Knots and hitches, by name only

Cow hitch, timber hitch, girth hitch: hitches TCI Magazine names for attaching slings and lowering devices.
Running bowline, closed clove, multiple half hitch: other hitches TCI Magazine lists for tying on a dead-eye sling.
Clove hitch, figure eight, sheet bend, truckers hitch: knots named in the 1989 paper.
Choker hitch, basket hitch: sling configurations defined in OSHA 1910.184. In a choker one end passes under the load and through an end attachment. In a basket the sling passes under the load with both ends on the hook.
Prusik loop: in the New South Wales code, a loop of rope smaller in diameter than the climbing rope, attached to it with a prusik knot.

Rigging methods

Natural crotch rigging: running the line through a fork or union that is part of the tree. The 1989 paper says natural crotches work when they are strong enough and in the right position.
False crotch: a rigged support for the line, built with a block and a sling in the 1989 paper. The New Zealand code defines it as any system other than a natural crotch. It says one that supports a climbing line must have rings or a pulley, with each part rated to at least 22 kN.
Butt hitch: a single hitch tied near the point of cut, so the tip drops (1989 paper).
Tip tie: a single hitch at the tip, so the butt falls away and down (1989 paper).
Double hitch: a tip tie combined with a butt hitch (1989 paper).
Negative rigging: a term used in the TCI Magazine pointers on lowering devices, which ties it to shock or impact loading on the tree and the climber. The article does not define it.
Speed-line: a line rigged to a ground anchor, with a come-along to adjust tension, in the 1989 paper.
Taking wraps: wrapping the rope around a bollard or trunk to add friction.
Locking off: holding the load line static. TCI Magazine describes ears on a lowering device made for that purpose.
Blocking: in the New South Wales code, taking the trunk down by gradually removing manageable sections after the canopy has gone.
Sectional felling: in the New South Wales code, felling sections of the tree by cutting at height and letting each section fall, as against lowering it on a rope.
Dismantling: the New Zealand code's word for reducing a tree's size or height in sections or pieces from aloft.

Load words

Working load limit (WLL): the maximum working load the manufacturer designed the item for. TCI Magazine says it is the minimum breaking load divided by a safety factor.
Minimum breaking load (MBL): the figure a WLL is worked out from, per the same article.
Safe working load (SWL): the maximum load equipment can safely lift. The UK HSE lifting equipment page says lifting equipment must be marked with it. The New Zealand code defines it as the figure the manufacturer specifies.
Rated capacity: the term OSHA uses for a sling's limit. OSHA 1910.184 uses "rated capacity or working load limit" for the maximum working load of a sling.
Dynamic load, shock load: a sudden load on the system. The New South Wales code defines shock load as the dynamic load on a rope or rigging apparatus when a moving object or a falling person is stopped. TCI Magazine warns that too much friction at the ground device can lock a load off and create one.
Kilonewton (kN): a unit of force. The New Zealand code says 1 kN is about 100 kilograms.
Proof test: a tension test done by the sling maker to check construction and workmanship (OSHA 1910.184).

A few figures a code puts on rigging gear, quoted and not advised:

Item	What the code says	Source
Climbing line	22 kN breaking strain when new	New Zealand code
False crotch parts	Each rated to at least 22 kN	New Zealand code
Strops and tag lines	Ultimate breaking strength of three times their safe working load, inspected regularly for wear	New Zealand code

Who does what on the ground

Ground worker: in the New South Wales code, the person responsible for controlling the load. The code also says using lowering ropes takes co-ordination between at least two competent people.
Drop zone: any area where parts of the tree may be felled or dropped (New South Wales code).
Hanger: a partly cut branch left in the tree. The New Zealand code says hangers must not be left unsecured when work ends.

Calls on the job

The New Zealand code says effective communication must be set up between the arborist in the tree and the ground crew before cutting or dropping branches. It does not set the words. A TreeBuzz forum thread, which is crew talk and not a rule, names these:

Stand clear: said by the climber. The ground answers "all clear".
Headache: said by the climber to mean get out of the way. The ground answers "clear".
Coming under: said by a ground worker who is entering the drop zone.

The thread says calls vary by crew and should be agreed before work starts.