Glossary of Technical Theatre Terms – Rigging

American Society for the Testing of Materials. Founded in 1898 and based in Pennsylvania. The ASTM arose out of efforts by Charles Dudley to standardise specifications for materials used across the construction of the Pennsylvania Railroad. 
ASTM Website

See BAR.

Scaffolding Base Plate A metal plate which prevents damage to floors when using scaffolding or trussing.

The generic rigger's term for using a basket hitch with an extra shackle to ease or speed fitting or removing slings at height or in awkward situations.
Submitted by Chris Higgs

A method of slinging that employs a sling wrapped around an object and both ends or eyes being connected by a component at the support point, hook, etc..
To lift a load as if in a basket.
Submitted by Chris Higgs

Rigging term: In a BASKET assembly the basket shackle is the bow shackle connecting basket hitch sling to the rest of the lifting system (motor, down leg, etc..) Sometimes called the base shackle (US).
Submitted by Chris Higgs

(US) An American lever hoist, the name of which is often used generically for any lever chain hoist.
Submitted by Chris Higgs

Marine rigging term for making off a line. Often encountered in climbing and mountaineering meaning the actions of rope management in arresting falls.
The belay is the attachment point to a rockface or structure. The belayer is the person tending the rope and belaying equipment (see DYNAMIC BRAKING) and 'to belay' means to perform the action of belaying. Originally with just gloved hands, now via sophisticated friction devices.
Submitted by Chris Higgs

A pulley in a frame which forms part of a grid system above a theatre stage, which carries a line to lift an item, either temporarily positioned as required for a show, or as part of a fixed installation. 
Also known as a LOFT BLOCK. 

Most riggers' knot of choice. Secure and easy to undo after heavy loading.
Submitted by Chris Higgs.


1) A vee-shaped arrangement of lifting equipment or rigging materials that enable load to be spread or shared between the 'legs' of the bridle, usually around four feet apart. Also, to reduce structural spans between suspension lines by creating such 'vees' at pick up points on the structure, or an assembly arranged to create a lifting point where required between two or more structural points.
2) The steering device on a horse.
Submitted by Chris Higgs

American device (from the overhead power distribution industry) that grips a wire rope by spring-loaded 'collet' jaws.Not designed for supporting weight.
Submitted by Chris Higgs

Sackcloth hessian, used as softening under steel wire rope slings. It's used because it's flexible and easy to use, and will not cause injury when dropped.
Submitted by Chris Higgs

Spring-loaded clip device used by climbers and also in stage rigging.
Named after the carbine gun which had a spring loaded gate.

Horizontal wire rope under tension (from the Latin 'catena' meaning a chain, the curve associated with a horizontally stretched chain length which is impossible to straighten due to it's self weight).
Submitted by Chris Higgs

Rigging term: A slinging pattern made by passing one end of a sling through the opposite end's eye or by making a 'lark's head' loop with an endless sling (also CHOKER HITCH (US) or STRANGLE (UK)). Useful, but reduces the SWL/WLL of the sling by 20%.
Submitted by Chris Higgs

The main horizontal member(s) in a truss/lattice structure.
Submitted by Chris Higgs

Long-running column in Lighting & Sound International magazine, by Rob Halliday, discovering the history and origins of many essential technologies and bits of equipment that have made entertainment technology what it is today. 
See the Lighting & Sound International archive for many examples. 

1) Purpose designed 'chain system' forging that allows a link of sling chain to be grabbed in order to shorten the reach or length of the chain. The forging ensures the 'grabbed' link is correctly loaded and no link is trapped or damaged.
2) A sailing term for a device that grips a control line or sheet in a modern rigging design.
Submitted by Chris Higgs

CM / C.M.
Manufacturer. (Columbus McKinnon Corporation.) American manufacturer of lifting equipment, including the Lodestar chain hoist range and STAC chain used in entertainment rigging.
Submitted by Chris Higgs

A lever hoist or tackle set designed for tensioning of pulling, particularly associated with catenary wire and guy rope rigging.
Submitted by Chris Higgs

Warning used when flying scenery or lighting bars (electrics). 
e.g. "First Electric Coming In", "Heads on Stage - LX3 coming in!" etc.

Scaffold Double Coupler (Doughty Engineering) Equipment used to join two other items together.
Commonly refers to a SCAFFOLD COUPLER (also known as a SCAFFOLD CLAMP or TUBE CLAMP).
A scaffold clamp is known as a Cheeseborough in the USA, believed to be named after Chesebro-Whitman Company of New York City. 

Crosby Forged Wire Rope Clip (Red U Bolt Clip, from the Crosby website) Manufacturer of shackles and lifting hardware (US, Canada and Belgium). The shackles are known as Crosby Clips. 
Crosby Group website

1) A pre-plotted height for a piece of scenery or lighting bar - 'that bar's on its dead'. The positional indicators on the rope (either PVC tape, or more traditionally cotton tape passed through the strands of the rope) are called DEADS. Sometimes flying pieces are given a number of extra deads, that may be colour coded, in addition to the 'in dead' (lower) and 'out dead' (higher - out of view). In the US, TRIM has the same meaning. Fluorescent ribbon is often used, through the fibres of the rope. The fluorescent colour shows very clearly under UV light, which is often used to light fly floors. 
2) Scenery or equipment not needed for current production - 'that table's dead'.
3) An electric circuit that has been switched off or has failed - 'the circuit's dead, you can change the lamp now'
Submitted by Chris Higgs

(Rigging) The short portion of wire looped around a thimble which wire rope clips are used to secure. 
E-Rigging - How to Install Wire Rope Clips

A rigging point direct to the grid / beams above the stage, not to a flying bar.

A static suspension, 'drop wire' or bracing line. A suspension without any lifting power.
Submitted by Chris Higgs

To replace a hoist or winch suspension with a dead line. Once the truss or piece is at trim, to tranfer the load onto 'dead lines' and remove the hoists or lifting devices.
Submitted by Chris Higgs

1) Colloquial term for a wire rope grip. Occasional a rope 'dog' or a girder 'dog' - a device that clamps.
2) See MOUSE.
Submitted by Chris Higgs.
E-Rigging - How to Install Wire Rope Clips

1) The effective travelling distance of a suspension barrel between the lowest it can reach with the scenic piece attached and the underside of the grid. The drift will be variable depending on the depth of a scenic piece suspended beneath the barrel. ie the comment 'there isn't enough drift' will usually mean that a piece cannot be flown out sufficently high to mask.
2) The wire that is used to achieve the drift (e.g. 'pass me a 2 metre drift, please').

A length of suspension wire of standard length with eyelets at each end between the counterweight bar and the top of the scenic piece flown from it.

The other bow shackle in a 'basket' assembly, the one that is actually screwed in use (unscrew it and the load drops!)
Submitted by Chris Higgs

The vertical wire rope used for rigging or suspending an object from a 'rigging point'. Often provided by a venue for their client to fix to (to maintain control over rigging practices). Also known as a DROPPER.
Submitted by Chris Higgs

The Drum and Shaft mechanism used the mechanical advantage of two sizes of winding drum to enable a single rope to operate a much heavier load, sometimes multiple loads simultaneously. Using a large Drum and Shaft mechanism, all of the painted wings of a scene, borders and backdrops can be flown out to reveal the next scene, by a single operator.
Also known as a Differential Windlass or Transformation Drum, and by the slang term Chinaman. 

File type for a CAD file (short for DraWinG). The format is used for storing two and three dimensional design data and metadata. It is the native format for several CAD packages including AutoCAD, IntelliCAD (and its variants) and Caddie. In addition, DWG is supported non-natively by many other CAD applications. The .bak (drawing backup), .dws (drawing standards), .dwt (drawing template) and .sv$ (temporary automatic save) files are also DWG files.

1) A DYNAMIC LOAD employs powered lifting equipment that magnifies the loading on the supporting equipment and structure due to the need to overcome the force of gravity.
2) A DYNAMIC ROPE is one that will absorb energy by stretching.
3) DYNAMIC BRAKING is a technique where progressively firmer braking is applied, as opposed to a sudden braking force. See also STATIC.
Submitted by Chris Higgs.

Fall Arrest systems are used by rigging crews who work at high level, and is designed to catch a fall and prevent the person from being hurt. The preferred method of protecting crews working at height is Fall Restraint, which prevents the fall from taking place by not allowing the person to reach the edge of the roof / stage. 
The systems consist of a harness and rigging to hold the person safely. There must also be a rescue plan in place so that the person can be rescued and taken to medical care as soon as possible after falling. 

The metal sleeve used to form an eye termination in steel wire rope which is pressed onto the rope under pressure from a hydraulic tool. Usually made from aluminium alloy, copper or steel.
Submitted by Chris Higgs

Doughty Engineering T30100 - Pipe to Pipe Coupler (Fish Plate - 48mm) Colloquial name for a coupler to join two pieces of pipe (e.g. 48mm scaffolding tube) together. 

Quick eyesplice in six strand wire ropes. Three adjacent strands are unlaid in order and laid up again in balance. The rope's core is removed. Strands 1 - 3 are then laid against strands 4 - 6 and re laid to form a six strand rope eye. The loose ends are tidied and a serving applied over the ends to prevent them unlaying. The splice is as strong as the rope.
Submitted by Chris Higgs

A piece of scenery or masking which is suspended above the stage on the flying system. 

Fouling occurs when a piece of flown scenery / drapery gets caught on a piece of scenery on the stage floor, or another piece of scenery / lighting bar etc in the rig. Fouling sometimes happens due to changes in temperature / air pressure causing lightweight scenery or curtains to move in a particular direction. Happens frequently in tightly-packed flying systems. 
Sometimes lighting designers need to remove additional equipment (e.g. barndoors, top hats) from lanterns in the rig because other scenery or curtains get caught on them. 

A rigid pole used to divert a piece of lightweight flying scenery to prevent it fouling / catching on another item (e.g. a piece of scenery or platform on the deck). 

A spanset with a metal wire running through it instead of a nylon core.  
GAC stands for Galvanised Aircraft Cable.

Warning that a flying bar is about to be lifted. 
e.g. "LX3 Going Out".

Proprietary device designed originally for agricultural use that can be used to form eye terminations in wire rope for non lifting applications.
Submitted by Chris Higgs

A fixed point in a venue with a known working load limit, which can be used to suspend a temporary lighting rig. 
Equipment must not be suspended from any point without a known limit. 

A wooden addition to the rear of a scenic flat to stiffen it, which consists of two pieces of wood screwed/glued together to form an L shape. 
Steel versions (known as Whalers) are used for steel-framed scenery. 

Generic term for a lifting machine.
Submitted by Chris Higgs

Acronym for International Code of Practice for Entertainment Rigging.
A new standard, published in 2017.
Download ICOPER at PLASA

Metal clamp designed to fit onto the kader grooved roof beams of a clear span marquee. Typically, the clamps are rated with a safe working load around 150kg each, but the marquee supplier must provide you with information about what the roof beams are rated to support. Extra care should be taken if there are unusual loads on the roof (rain / snow / wind).

A canvas tool bucket originally designed for 'utility' contractors in the US, stout canvas with a rope handle and plastic or leather base. Ideally suited to and adopted for collecting hoist chain. Available as strong and large enough for up to 30m lengths of 7mm / 5/16' hoist chain.
Submitted by Chris Higgs

Klein Tools Inc. have been making tools since 1857, the 'tool' referred to is a generic term for two items, the 'Chicago' or 'Haven' grip, which are self gripping wire rope pulling tools, useful for tensioning catenary wires and general wire rope gripping jobs in rigging.
Submitted by Chris Higgs

The direction and angle in which strands are 'twisted' in rope making) which in turn determines the 'hardness' of the lay (flexibility) in fibre ropes and the 'pitch' (frequency with which a strand appears when viewed along one side) of any rope.
Submitted by Chris Higgs

1) Each sling used as part of a multiple sling, e.g. a 'two leg sling' has two slings used as the 'legs' of the sling. A bridle 'leg' is therefore one half of a two 'leg' bridle, or one third of a three way bridle, etc.
2) See LEGS.
3) A part of a longer journey (e.g. the German leg of the tour covered Hamburg, Berlin and Frankfurt).
Rigging definition submitted by Chris Higgs

1) A rope length, once cut to length or installed for a specific function. (To cut a line from a coil of rope).
2) A request from an actor for a prompt when they have forgotten their next line. 
Submitted by Chris Higgs

Little Tom Clamp, Doughty Engineering A clamp made by Doughty Engineering, to enable a scaffold pole to be used at the top of a standard telescopic lighting stand to support two or more lanterns, or to form a vertical support for a longer scaffold pole to hang masking curtains or lightweight scenery cloth from. 

Abbreviation for Lifting Operations and Lifting Equipment Regulations 1998 (UK Health & Safety Executive).

Generic term for an electric chain hoist. (Rumoured to have been started by an enquiry as to whether 'CM' stood for 'chain motor').
Submitted by Chris Higgs

Term used when a self climbing motor is rigged conventionally, i.e motor up. Motor down is sometimes used to convey the opposite, but in general it is understood that all motors 'climb'.
Submitted by Chris Higgs

Mousing a shackle when rigging means using wire or a cable tie / zip tie to hold the shackle pin in place to stop it working loose. (NB the mousing device is not load bearing, it's only holding the pin in place).

Part of a flying system. A horizontally-mounted block used to divert the route of a lifting line so that it can reach the head block due to an obstruction.

The connection between structural members in a construction (from Latin, a knot).
Submitted by Chris Higgs

(UK) National Rigging Advisory Group
NRAG website

The side of the stage (either stage right or stage left) where the fly lines are operated from.

1) An error when flying a cloth or piece of scenery, where it's flown in too far. This will result in the cloth bunching up on the stage deck, or the piece of scenery potentially tilting and damaging other nearby equipment. When flying items always make sure the 'in dead' is clearly marked, and always slow down when approaching it to ensure it does not get passed, resulting in an overhaul. 
2) To give something (or somewhere) a major makeover by effectively taking it apart, repairing the bits, and putting it back together again. 

UK trade association for the mobile access tower industry. The acronym stands for Prefabricated Access Suppliers’ & Manufacturers’ Association Ltd.

Small handheld motor controller that plugs into a cable connected to a winch or other motorised system.

The rigging point or hanging point to which the lifting machine or suspension component is rigged. Can be temporary ('rigging the points'), or permanent, 'the house points' for example.
Submitted by Chris Higgs

(UK - Health & Safety) Abbreviation of Personal Protective Equipment. The equipment that's needed depends on the task and risk assessment but could include: steel toe-capped boots / shoes, protective headgear, gloves etc.

Quadbox Gearwrench Quad Spanner A double-ended, double-sided ratchet spanner designed to fulfill all of the requirements for a stage rigger.
In the UK, Quad spanners typically include 13mm, 17mm, 19mm, 21mm sockets, which fit M8, M10, M12 bolts and scaffold clips. 
A popular range in the US is made by Quadbox. 
See also Podger.

Old Norwegian for threading, any threading action, - lacing, choking etc..
Submitted by Chris Higgs

The rigging structure or existing structure used for rigging from.
Submitted by Chris Higgs

The technique involving the use of ropes in tension to enable access to workstations otherwise too dangerous or costly with traditional methods.
Submitted by Chris Higgs

An endless sling made of a coil of (man made) fibres sheathed in a protective man-made cover, flexible, soft, light weight and cheap
Submitted by Chris Higgs

Rolled Steel Joist. A type of steel beam used in construction, which has an I or H shaped cross-section, and is known as an I Beam. 

1) Climbing - abbr. for 'running belay'. An intermediate means of protection where an anchor is placed through which the climbing rope can run. In the event of a fall, the climber should fall only as far as the length of rope between him and the highest running belay he has arranged will allow. The rope absorbs the energy in the fall provided the belay and belaying is sound and the running belay holds firm.
2) A Tab Track Runner is a plastic or wooden wheeled support into which a curtain hook is clipped, which then runs along the tab track. There should be one runner for each curtain hook. Also known as a BOBBIN. See also TRAVELLER. 
Submitted by Chris Higgs

UK Health and Safety terminology. Can be defined as 'the integration of people, articles and substances in a suitable environment and workplace to produce and maintain an acceptable standard of safety. In this system, due consideration should be given to foreseeable emergencies and the provision of adequate facilities'
Submitted by Chris Higgs

Safety Chain, unrated An old form of secondary suspension used on rigged equipment. 
Because the chain cannot be rated to carry a specific load, safety chains should no longer be used in this application, but should be replaced by rated safety bonds. 

1) System of pipes, clamps and boards which is used in the construction industry to form levels to improve access to high buildings either during construction or maintenance. Shortened to Scaff. 
2) The same system can be used for set construction, with adequate supervision by experienced / qualified persons. 
3) Scaff tubes / pipes are 48mm in diameter and are used as vertical legs on platform systems by various manufacturers including Steeldeck, Metrodeck, Prolyte Staging etc. Originally made of steel, scaff tubes are usually now made from aluminium which is a much lighter weight and therefore easier to work with and safer from a manual handling point of view.
4) Horizontal bars to rig lighting equipment from are made from scaffold tubes (48mm diameter). 

A metal connecting device originally for joining chain, comprising two parts. An open link connects the items to be joined and a pin is fitted to make the link complete. Many sizes and designs exist, the most common to the entertainment world being the screw pin 'bow' or 'anchor' shackle, originally for fixing chains to anchor stocks. The pin should always loaded in shear, not in tension.
Submitted by Chris Higgs

A 'steel' that is fitted at manufacture with a loose protective sleeve of PVC tubing (ideally transparent, to permit examination of the wire rope) or roundsling sheathing.
Submitted by Chris Higgs

The materials used to protect a sling or an object from sling damage (burlap or PVC sheathing etc.)
Submitted by Chris Higgs

Part of the flying system, commonly used in the US. Spreader plates are thin steel plates with holes, through which the arbor connecting rods pass. The plates are lowered onto the counterweights approximately every two feet, to ensure the rod spacing is maintained. A locking plate is lowered onto the finished stack of weights and spreader plates and is secured in place with a thumbscrew.

Columbus McKinnon 'Special Theatrical Alloy Chain'. Long link alloy chain sling product for use in line only. Comprises 5.4 ton 3' links in a three or five foot length. Used in bridle adjustment and as a versatile secondary suspension component.
Submitted by Chris Higgs

1) Refers to a steel blue / pale blue lighting gel. (Lee 117) (e.g. 'Use the Steel General Cover for the scene in the castle'). See also STRAW.
2) Many set construction now uses steel frames with timber cladding. Steel is stronger and lighter weight compared to timber of the same size.
3) Generic term used for a plain wire rope sling. Also used when referring to roof structural steel and individual steel beams or scaffold materials and so on.
Additional information submitted by Chris Higgs.

To install secondary 'steel' suspensions, deads or bypasses ('safeties').
Submitted by Chris Higgs

Steel wire rope sling used to extend the length or reach of a hoist chain or to allow a hoist to reach the ground from the point, (a 'down leg').
Submitted by Chris Higgs

1) (Manufacturer) Maker of lanterns, lighting desks and dimmers in the UK and Worldwide.
2) The bundle of individual fibres or wires that make up one of the helical elements in a rope.
Strand Lighting website
Strand Archive

Acronym for Steel Wire Rope. 

A proprietary wire rope ferrule/press tool system. Manufactured by Talurit AB in Sweden.
Submitted by Chris Higgs
Talurit website

Abbreviated to TPLK. A temporary anchor used as part of a fall-arrest system. 
Templins Flexible Anchor

Abbreviated to TWG. A mesh above the stage comprised of steel wire under tension which can be safely walked on, and is transparent to light. 

Protective metal or plastic loop used to reinforce and protect the eye at the end of a wire rope. Specifications vary according to use, but all conform to basic rules of proportion in forming the correct size loop for the rope diameter/type.
Submitted by Chris Higgs

A wire rope hoist that utilises twin sets of jaws to grip on the rope. Actually a French manufacturer of lifting equipment, but like Hoover, one particular style was so successful, the name stuck to that type of winch.
Submitted by Chris Higgs

1) See Cue to Cue.
2) The practice of reversing 'hemp' lines in a theatre to spread wear over as great a length of rope as possible. Over a period of time this practice can considerably increase rope lifetime, especially if lines are rotated between sets as well as positions in the grid (The short of set 1 becomes the long of set 40, for example)
Additional information submitted by Chris Higgs

Torx Woodscrew (T10 head) Type of screw fitting, consisting of a 6-point star shape. This type of screw is increasingly being used in construction / scenic industries, as it is more hard-wearing (and more difficult to damage the head) than normal Philips / Pozi-Drive screws. 
Torx screws can also be found in some audio-visual / consumer equipment, which has no user-servicable parts inside. 
There are a wide range of sizes of Torx screw heads, denoted by 'T' then a number. Common sizes are T10, T15, T25 (although the scale runs from T1 to T100). Some manufacturers use TX numbers (rather than T) for the required screwdriver size. 
Wikipedia entry

A framework of alloy bars and triangular cross-bracing (commonly around 50mm diameter) providing a rigid structure, particularly useful for hanging lights where no permanent facility is available. Very often box-shaped in cross section, so known as BOX TRUSS. This type of truss is useful for touring as lanterns / speakers etc can be hung inside the truss which protects them when loading and takes up less space in the truck.
You should only use truss from reputable manufacturers, and should check the manufacturers' website for instructions on how to use it, and what limitations it may have. 
Rigging a truss incorrectly can vastly reduce its' safe working load, and can result in damage to the truss,or a far more serious failure. Always seek advice from professionals, and do not attempt to rig equipment without proper advice or supervision. 
The cross-sectional shape of truss can either be FLAT (known as Ladder Truss), SQUARE (known as Box Truss) or TRIANGULAR (known as Tri-Truss). 

Large diameter tapered metal pin (also known as a bullet pin) which is used to hold pieces of truss together. The pin has a hole at the far end which is used with an R-Clip to prevent it coming out accidentally. Different sizes of truss pin are used for different manufacturers' truss. 

Unrated strong thread comprised of a number of strands of (e.g.) cotton or hemp twisted together.
Should not be used in rigging. 
See also WHIP

Uniformly Distributed Load. Some flying systems might have a UDL rating stated per bar, which is the maximum load that should be applied across the full width of the bar. A Point Load might also be shown, which is the maximum weight of a single item (or load) on the bar. 
See also WLL (Working Load Limit). 

The European manufacturer of self-climbing chain hoists and other lifting equipment.
Verlinde website
Submitted by Chris Higgs

A low-profile steel stiffener for steel-framed scenic flats.
See also Hogs Trough. 

To apply whipping twine to the ends of a rope to prevent it unlaying.
Also, in rigging, a WHIP is a single line over a single sheave used as a handling aid.
Submitted by Chris Higgs

A mechanical or motorised device for hauling a heavy load horizontally or up an incline. 
A HOIST is used to lift a load vertically.

(UK - Health & Safety) Abbreviation for Working Load Limit - the maximum weight that lifting equipment can carry, when used correctly, without fear of breaking. 
See also SWL, which WLL has now replaced. 

1) Rigging term: To wrap a beam or truss with a sling, or the short sling used for so doing, e.g. a 'truss wrap' is used to wrap a truss.
2) In film and television production, the end of a day's work or session, OR the end of the project for either an individual performer, or everyone. For example 'That's a wrap for John Brown! Thanks for your work John'. Often followed by a Wrap Party. This event should be attended by as many people involved in the project / show, so should not happen while the crew are clearing up / getting out. 
Submitted by Chris Higgs