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Industry terms have you confused?  Check out our glossary index below:

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A-Guide – A-shaped aluminum members fixed in parallel rows for the purpose of guiding arbors or clews. They are intended for use on counterweighted systems employing compensating chains and in zones of high seismic activity. This is a Clancy product.

Act Curtain – A curtain (sometimes designed for a specific show) that is opened to signal the beginning of a performance. The Front Curtain is often used for this purpose.

Apron – The portion of stage that extends beyond the proscenium opening.

Arbor – A carriage or rack that contains weights, usually flame cut steel or cast iron, in sufficient quantity to balance a load.

Arbor Pit – An area below the stage that permits guides and arbors to travel though an opening in the stage floor, permitting greater travel for counterweight arbors and pipe battens.

Audience – The area of the theatre where visitors sit to view a stage performance.

Auditorium – A hall or seating area within the hall where the audience views a performance.

Austrian Curtain – A curtain that is raised (opened) with brailed lifting lines and is sewn with both vertical and horizontal fullness.

Batten – A bar, usually made from steel pipe, from which scenery, lights and curtains are hung.

Batten Clamp – see “Pipe Clamp.”

Beam Clamp – A device from which a load is hung, attached to the flange of a steel beam without altering the beam in any way.

Belaying Pin – A wood or steel rod, inserted into a hole in a pin rail, that secures ropes attached to a load.

Block – An assembly that consists of one or more sheaves and axles in a housing.

Border Curtain or Teaser – A curtain used to define the top limit of the stage and to mask or hide lights and unused scenery and curtains.

Brail Curtain – A curtain that is raised (opened) with brail type lift lines and is sewn flat or has horizontal fullness.

Breaking Strength – The load at which a failure occurs.

Bridle – An assembly that splits a lift line into two separated attachment points. Used to support trusses or to provide extra support along a pipe batten to limit deflection.

Cable Clip – A device to mechanically fasten cables, consisting of bolts, nuts, and pads that bear against the cable to prevent crushing and slippage.

Cable Roller – A roller assembly designed to prevent moving cables from contacting any part of a building or adjacent rigging. Not intended to change cable direction or carry loads.

Capstan Winch – a winch, usually portable, with an un-grooved drum design to assist in moving heavy loads. An operator wraps a rope around the drum and pulls to tighten the rope on the drum. Friction causes the rope to travel with the rotating drum.

Carriage – See “Arbor.”

Clew – Device that connects several ropes or cables to one, usually stronger, rope or cable.

Compensating Line – A system of light and heavy chains that balances lift line weight as it transfers from the batten to the arbor side of a moving counterweight set.

Competent Person – The ESTA/ANSI Series E1 standards definition is a person who is capable of identifying existing and predictable hazards in the workplace, and who is authorized to take prompt corrective measures to eliminate them.

Contour Curtain – A brail or Austrian curtain rigged so that each lift line may be operated separately to form different shaped openings.

Counterweight – (n) Weights, usually flame cut steel or cast iron, that are placed in counterweight arbors to balance the weight of loads hung on battens. (v) The act of adding of removing weight from a set in order to achieve a balanced system.

Counterweight Set – A rigging system where the load is balanced by a counterweight so that only a small force is required to overcome friction and move the load.

Cross Over – A corridor created by an upstage curtain and the rear stage wall that allows actors and other personnel to cross from one side of the stage to the other side out of sight of the audience.

Cyclorama – (1) Curtains at the rear of the performance area used to represent the sky or distant areas. (2) Set of borders, legs, and drops used to define the limits of a performance area.

D/d Ratio – The ratio between the tread diameter (D) of the drum or sheave and the cable diameter (d). Small ratios reduce the service life of cables.

Dead Hung  – A term used to describe static rigging.  Usually consisting of grids, battens, and/or acoustic panels that do not raise or lower and are permanently attached to the ceiling structure.

Dash Pot – An adjustable, hydraulic ram that smoothly slows and stops a moving object.

Dead End – The end of a rope or part of a device that is not active or load carrying.

Dead Haul – Pulling a load that is not counterbalanced.

Dead Load – The permanent or non-removable part of a system load (i.e., the weight of a batten versus the load hung from it.)

Design Life – The minimum expected life of the system expressed in hours or cycles of operation.

Design Load – The load that a system or equipment item is designed to carry. This load can be made up of dead loads, live loads, dynamic loads, and environmental forces.

Double Purchase – A rope or cable that passes from a lifting device (arbor, winch, or person) over a block, to a block attached to the load, and tied off at the previous block, is double purchased. The system allows twice as much load to be raised for a given effort, but the rope or cable must be pulled twice as far, so total work done remains the same.

Down Stage – The area of the stage that is closest to the audience. See “Raked Stage.”

Drum winch – A winch with a drum for wrapping up cable as it is taken up.

Emergency Stop Circuit – This should be a failsafe, separately wired circuit in rigging control that stops any and all controlled machinery in an emergency. The circuit can be triggered by depressing the Emergency Stop pushbuttons and by various automatic sensors and limit switches. To re-start it is necessary to take one or more specific actions to begin motion.

Equal Pitch – All grooves in the sheave have the same pitch diameter so that the center of each line travels the same distance as the sheave rotates one revolution.

Factor of Safety – The ratio between the rated working load of a component or system and its minimum ultimate breaking strength.

Field Check – A visit made to an installation project for the purpose of obtaining project measurements, checking its status, and finding potential conflicts.

Fire Curtain – A curtain that closes automatically in event of a fire to prevent heat, smoke and flames on the stage from reaching the audience.

Fireline – Firelines are installed around the perimeter of a stage-proscenium arch to hold the fire safety curtain open. Firelines connect the curtain to all manual electrical and heat activated devices that release the safety curtain.

Fleet Angle – The angle formed between the centerline of a sheave or drum and another sheave or fixed point.

Floor Block – Pulley mounted at the floor to hold a rope or cable in position and to reverse its direction. Floor blocks meant for rope often incorporate a means of adjustment to accommodate changes in length due to loads or environmental conditions.

Fly – The act of lifting scenery, lights, and curtains.

Fly Gallery – A gallery or catwalk above the stage floor from which counterweight and hemp (rope) rigging is operated.

Fly Loft – The space between the roof and the performance area that is not visible to the audience.

Front Curtain – A curtain used to define the stage location to the arriving audience. It is (House curtain) often the curtain closest to the audience and may also perform the function of an “Act Curtain.”

Fullness – Additional fabric that is added to be sewn into pleats. 100 percent fullness means that the curtain would be double its finished width before the pleats are made.

Gearmotor – The combination of a gearbox and motor in a single unit. The motor may also incorporate a brake.

Gridiron (Grid) – An open floor, usually made from light steel channels or grating, that is located near the roof steel. It provides mounting locations for rigging equipment and access to that equipment for inspection and maintenance.

Guide – To control the movement of rigging devices by means of slides or rollers moving in tracks or on stretched cables.

Guide Shoe – A device attached to a counterweight arbor or tension block to engage guide rails and control the movement of the arbor.

Guide Rails – Components that confine and control the movement of counterweight arbors and tension floor blocks. See “J-Guide, A-Guide, Lattice Track, T-Guide, and Wire Guide.”

Hand Line – A line, usually rope, that is pulled by hand to lift or control the movement of a load.

Head Block – A pulley mounted to support steel that changes the direction of lift and operating lines between the loft blocks and an arbor or winch.

Head Block Beams – Structural framing designed to support the head blocks and all related loads. Usually consisting of one or two beams and associated bracing members.

Hemp Rigging (Rope or Spotline) - A rigging system that employs ropes and sandbags instead or counterweight arbors or other devices. Usually used for temporary rigging.

Hoist – A powered machine used for raising, lowering, and holding objects.  See ETC RIGGING


House – See “Auditorium.”

House Left/Right – The sides of an auditorium as seen by an audience member while facing the stage.

Idler – A pulley designed to support one or more cables but not to make direction changes.

Incremental Block – A multi-grooved pulley that supports and changes the direction of cables between the load and the head block and that supports other, more distant, lines in the set.

Index Light – A series of lamps in a special housing designed to illuminate the locking or pinrail area.

Index Strip – A device located at the front of a locking rail to hold line set identification labels.

J-Guide – J-shaped aluminum members fixed in parallel rows for the purpose of guiding arbors or clews.

Lattice Track – A parallel pair of angles or other structural members that guide an arbor or clew. Low friction slides or roller guides are placed on both sides of the device to be guided.

Lead Line – See “Lift Line.”

Leg, Tormentor or Wing Curtains – A curtain used to define the side limit of the stage and to mask or hide actors, lights, and unused scenery in the off stage area

Lift Line – Any rope or cable located between a load and a winch or counterweight arbor.

Lighting Bridge – A walkway across the stage (fixed or flown) where lights are hung and where they may be adjusted and maintained.

Line Set – A system consisting of one or more lift lines and related components operating together to lift, lower, or suspend or a load.

Line Shaft Winch – A winch with a series of cable drums connected to a gearbox by a common shaft.

Live End – The end of a rope or part of a device that is active or load carrying.

Live Load – That part of a system that may be added or deleted (i.e., lights hung from a pipe batten.)

Load Brake – A secondary brake that holds the full load in the system, usually in the case of a failure in the system.

Loading Gallery (Loading Bridge) – A gallery above the stage floor where technicians add and remove counterweights from the arbors. Usually located so technicians have access to arbors when battens are at their lowest position.

Loading Rail – A structural railing designed to support rope locks in a way that allows them to be safely operated. It carries any out of balance loads from the rigging system held by rope locks.

Locking Collar – A fastening device located on the counterweight arbor rods above the upper spreader plate and counterweights and intended to help keep the weights in the arbor during a hard impact.

Loft Block – A pulley mounted to the gridiron or support steel that supports and changes the direction of a lift line cable between the load and the head block.

Masking – A set of curtains or scenic elements used to define the visual limits of a performance area.

Motor (Primary) Brake – A brake that is mounted at the motor. It has a low torque capacity and fast response. Used for normal stopping and holding duty on a motorized hoist.

Mouse – To wrap the end of a rope, cable or turnbuckle to prevent it from unwinding.

Mule Block – A pulley that supports and changes the direction or one or more cables traveling between loft blocks and head block.

Mule Winch – See “Capstan Winch.”

Multi-Sheave Block – A block which contains a number of sheaves and sets of bearings so that each rope or cable can operate independently.

Off Stage – The stage floor area that is not part of the acting area and is not visible to the audience.

Olio Curtain – A curtain located between the “Front” or “Act” curtains and the “Rear” curtain that closes off a portion of the acting area for more intimate presentations. It is often colored or decorative.

On Stage – The portion of the stage area visible to the audience, usually defined by masking curtains, scenery, an orchestra shell, or by lighting.

Orchestra – (1) A group of musicians who play instrumental selections. (2) The portion of the auditorium on the main floor that is closest to the musicians and the acting area.

Orchestra Lift – A moving platform that is used to adjust the elevation of the musicians in relation to the stage and auditorium. Usually operates within the confines of an orchestra pit.

Orchestra Pit – A depressed area between the stage and audience seating area where musicians sit, so the audience can hear the music and see the performance over the heads of the musicians.

Orchestra Shell – An enclosure on stage, consisting of walls and a ceiling that reflects sound into the auditorium. Usually decorative in nature.

Over Speed Brake – A mechanical and fully automatic brake that stops a winched load that is moving too fast, indicating an out of control machine. Normally located as close as possible to the lifted load and rated for the full capacity of the load plus a reserve to slow the load to a stop.

Out-of-Balance – A condition that exists when the weight of a batten, fittings, and attached loads do not equal that of counterbalancing equipment, such as counterweight and an arbor. For safe and efficient use, manually operated sets should be balanced to within 50 pounds of neutral.

Outrigger – A barrier device that protects counterweight arbors from scenery, etc. that may be leaned against them. Also often supports index lights.

Pileup Winch – Winch with special drum that piles up cable in a single layer in a slot. Also called a “Yo-Yo” drum winch.

Pinrail – A railing with holes to accept belaying pins. May also act as a safety railing at the edge of a gallery or walkway.

Pipe Clamp – Clamping device that bolts around a pipe for attachment of chain or cable hangers.

Pipe Grid – Horizontal structure hung over a stage or auditorium to support lights and scenery. Made from pipes crossing on right angles at set intervals.

Pipe Weight – The amount of weight to permanently remain on an arbor to counterbalance an empty batten.  This load is usually strapped to the arbor and painted a bright color to ensure that it is not accidentally removed.

Pitch Diameter – Diameter of a sheave or drum measured from the centerline of the cable wrapped around it.

Pivot Block – A pulley designed to adjust to structures at odd angles.

Point Hoist – A single line winch, used singularly or in groups, to hold a load at a specific point over the stage. They are the motorized equivalent of spot lines, providing the greatest flexibility possible in motorized rigging. (similar to a dimmer per circuit in lighting.)

Portal – A portal consists of a header (border) and tabs (legs) that can be moved to adust the size and shape of the proscenium opening to fit various performance needs. It is usually located just up stage of the front curtain and may have provision for mounting lights.

PowerLift – A J.R. Clancy Product. See “Zero Fleet Angle Winch.”

Purchase Line – See “Hand Line.”

Proscenium – The dividing wall or barrier between the audience and stage.

Proscenium Arch – The opening in the proscenium through which the audience views a performance.

Qualified Person – The ESTA/ANSI series E1 standards definition is a person who by possession of a recognized degree or certificate of professional standing, or who by extensive knowledge, training, and experience, has successfully demonstrated the ability to solve or resolve problems relating to subject matter and work.

Raked Stage – A sloped platform that is lower near the audience for better visibility and higher at the rear, providing the illusion of distance. This is the source for the terms “Down Stage” and “Upstage.”

Rated Load – See “Recommended Working Load.”

Recommended Working Load – The Recommended Working Load (RWL) is the maximum load which J.R. Clancy, Inc. recommends be applied to current, listed products which are in “like new” condition and which have been properly installed, maintained and operated.

Reverse Bend – Passing a rope over a series of blocks so the rope is bent in opposing directions.

Rigging – All of the hardware used to lift, lower, and hold performance equipment on or above a stage.

Rope Lock – A cam operated device that clamps the hand line that is attached to an arbor in order to prevent movement. Designed to hold the unbalanced load in a set.

Safe Working Load – “See Recommended Working Load (RWL).”

Safety Chain – (1) A secondary support line, usually of chain, that supports a fire curtain or other device when the primary support cable becomes slack for any reason. (2) The extra weight of fire curtain safety chains help the fire curtain accelerate at the start of its travel.

Sag Bar – A support rail, usually of wood or plastic, that keeps cables from sagging over a horizontal span due to their own weight. Sag Bars don’t carry any loads.

Sandbag – A fabric bag that can be filled with sand and attached to rope rigging as a counterbalance to the load hung from the set.

Scrim – A curtain made from a semitransparent material that looks solid when lit from the audience side and becomes almost invisible when back lit.

Self-Climbing – A pipe grid or batten that has an integral device for raising and lowering.

Set – A system of cables, pulleys, lifting devices and battens that holds a specific set of scenic elements, curtains or lights.

Shackle – A U-shaped device with holes at each end to accommodate a pin or bolt; used to connect rope, cable, or chain to another device or a hanging point.

Sheave – A component with a groove around its circumference to support and contain a rope or cable and a bearing at its center to permit rotation about a shaft.

Shock Load – Loads generated by the rapid application of a force or motion to an object or by the collision of moving bodies.

Single Purchase – A rope or cable passing from a lifting device (arbor, winch, or person) over a block, or series of blocks, to a load is single purchased. Force must be exerted equal to the load to be held or raised.

Slack Line – A cable that droops or leaves the sheave or drum groove because it lacks tension in the line.

Smoke Pocket – A slot, usually of fabricated steel, that supports a guide system at the edges of a fire safety curtain and that helps to prevent smoke from passing around the edges of the curtain.

Spotline Rigging – A temporary rigging system designed to be easily installed. Often rigged with rope instead of counterweight.

Spreader Plates – Thin plates located on counterweight arbor rods, placed at 2’ intervals between the counterweights, to prevent the rods from spreading apart under a sudden impact load and releasing the counterweights.

Stage – A platform on which performances are given.

Stage Left/Right – The left and right sides of a stage as seen by an actor standing on stage facing the audience.

Stage Lift – A portion of the stage floor that may be raised or lowered.

Straight Lift Curtain – A curtain that can be raised (opened) without folding in any way.

Submittal Drawings – Drawings that are prepared by the equipment supplier or installer to describe the equipment and details of the installation to the client. Approval of the drawings by the client indicates his acceptance of the proposed equipment, locations, and conditions of the installation.

SureLock – A special rope made by J.R. Clancy, Inc. designed to it cannot be opened when the counterweight set is more than 50 pounds out of balance in etiher direction. See also “Rope Lock.”

Swivel Block – A pulley that rotates in the horizontal plane.

Tab – (1) A masking leg that is mounted at right angles to the front of the stage. (2) See “Portal.”

Tag Line – A line attached to a load to assist in controlling its movement.

Tandem Block – A block with two or more sheaves on separate shafts within a common housing.

Tee Guides – “T” shaped members placed in parallel rows to guide arbors or clews. Guides may consist of low friction slides or rollers.

Tension Block – See “Floor Block.”

Thimble – A grooved fitting around which a rope or cable is bent to form an eye. It supports the rope or cable and prevents kinking and wear.

Tieoff Bracket – A bracket attached to rigging blocks, gridiron, or other structure to hold wires for guiding clews.

Traction Drive Winch – Winch with a V-grooved drum that uses friction between cables and the sides of the grooves to engage the pulling cables. Increasing the cable tension causes the cables to jam tighter in the V grooves.

Travel – The path of moving stage equipment and the distance moved.

Traveler – A curtain on a track that can be opened or closed to reveal or mask a portion of the stage.

Tread Diameter – The diameter of a sheave measured at the bottom of its groove.

Tread Pressure – The radial pressure (P) of a rope against a sheave groove is equal to the load (L) in the rope divided by the tread radius (R) times the rope diameter (d). L=PRd. P=L/Rd.

Trim – (1) A load is “in trim” when the equipment load equals counterbalancing weight. (2) A set or element is trimmed when it has been placed in the desired position within the performance area.

Trim Chain – A length of chain placed between a lift line and a pipe batten or scenic element to connect them and to facilitate minor height adjustment of the load.

Tripped – A curtain or scenic element is lifted by a second set of lines attached at the bottom or intermediate point on the piece. Pulling the lines will cause the piece to fold in half of thirds. Note: If the piece is counterbalanced, the weight balance will shift as the piece is tripped.

Truss Batten – Two or more pipes or other linear members fabricated together with cross bracing in a trussed configuration. Used in place of a pipe batten for heavy loads or extended distances between lift lines.

Under Hung – Hung from the bottom of a beam or structure.

Up Stage – The portion of the stage that is furthest from the audience. See “Raked Stage.”

Upright – Resting on top of a beam or structure.

Valance – See “Border Curtain.” Usually a special border associated with the “Front Curtain.” May be permanently fixed within the proscenium arch.

Wall Batten – Horizontal structural members to which guide tracks are attached.

Wall Knee – Bracket that attaches a wall batten to the building structure.

Well – Gaps between gridiron members intended for the mounting and support of loft blocks on boundary channels and for allowing the free passage of cables.

Wings – The portion of the stage area located to either side of the acting area.

Wire Grid – An open floor that supports lights or provides access to theatrical equipment. It is formed of woven cables attached to and supported by a structural frame.

Zero Fleet Angle Winch – A winch with cables that exit the winch at fixed points so that fleet angles do not need to be considered in the rigging layout. This is accomplished by incorporating a moving head block or by making the drum move in relation to the head block per Izenour/Clancy designs dating back from the early 1960s.

Loading Gallery
Fly Loft
Fire Curtain
Line Shaft
Dea Hung
Counter Weight Set
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