Stage Terms A-F
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.
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 Safety 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.