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Theatre Stage Machinery

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A person coming through a stage trap door lit from below.

'All the worlds a stage' wrote William Shakespeare. Place an actor in any space, with a few props, and they will act out a story. For example, the Royal Shakespeare Company's1 production of Nicholas Nickleby or Susan Hill's ghost story of Woman in Black. Our imagination provides the scenery.

Theatre spectacle requires that we actually see something happen before our eyes. Simple spaces in which to perform are replaced by a vast machine, in which the actor is placed. Modern examples of this type of show are musicals such as Phantom of the Opera or Les Misérables, where the machinery of the stage allows scenes to flow together with film-like quality. Some productions require a show stopping moment as in Miss Saigon or Chitty Chitty Bang Bang. A moving train, car or helicopter on stage often brings the house to thunderous applause! All of this would be impossible without the use of a fully equipped stage area.

Stage machinery is nothing new. Lifts raised animals to the arena floor of the Coliseum in 1st Century Rome. Contemporary reports suggest one of Shakespeare's Globe theatres2 had a trap door allowing actors to enter the 'hell' below the stage, while winching machinery lowered an actor from the 'heaven' above the stage. The original London production of Phantom of the Opera uses stage mechanisms built by the Victorians although updated for computer control and crewing economics.

Opera houses use large pieces of scenery, which are heavy! To move such large pieces of scenery requires large numbers of stagehands. The use of modern stage machinery allows the same large pieces of scenery to be moved more safely, quickly and easily. This reduces the size of the stage crew.

Fly Tower

Above the stage in most large modern theatres is a space called the 'fly tower', which provides walkways and working platforms above the stage, and storage space for scenery not required on stage.

Viewed from the outside, fly towers rise high above the rest of the building. Most architects find it hard to design theatres with pleasing lines and shapes, when the fly tower may be twice the height of the stage. One noticeable design solution to the fly tower is at The City of London Barbican Arts Complex, where a glass conservatory surrounds the fly tower.

Scenery flown3 is attached to five centimetre diameter steel pipes, or stronger load bearing battens, which hang parallel to the front of the stage. Each bar hangs from a system of hemp ropes or steel hawsers to a system of pulleys, winches and counterweights - which balance load, making movement easy - allowing scenery to be smoothly lowered or raised during a production.

To enable complex scene changes and different positioning, a number of bars are hung at regular intervals from the front of the stage to the back wall or cyclorama. Undertaking the attachment of scenery to bars is performed during the rigging time, before the show opens to the public. During rigging, bars are lowered to stage floor level, giving stagehands ease of movement, and where there is no risk of dropping anything from a great height onto the heads of people below.

Technicians called 'Flymen' operate each individual fly bar. Flying scenery may be assisted by the usage of electrical or hydraulic systems, allowing the option of computer control.

Originally nothing more than simple painted backcloths or curtains (usually referred to as 'tabs') were flown. It is now common to hang large three dimensional items of scenery, each weighing several tons, that may be the full height of the stage.

With the increase in weight of scenery, it would be easy to overload the safe working load of the fly tower if limits were not introduced.

Safe working loads (SWLs) are assessed by engineers, who take into consideration the maximum weight the fly tower can support and the number of bars fitted. Each bar is individually assessed and tested to determine its maximum carrying capacity.

Safety Curtains

Theatres in the past used naked flames and gas for lighting, along with lots of flammable materials. Fires in theatres were commonplace; even today with modern Health and Safety precautions in place, theatres still catch fire. Theatres with fly towers have the added fire problem that they can act like a chimney, causing any fire to burn more fiercely.

To reduce the risk to an audience, positioned next to the proscenium arch4 (where used) is a special safety feature, the safety curtain, sometimes called an 'Iron' or 'Fire' curtain.

It is made of materials that do not easily ignite - asbestos and iron used to be common materials, but steel is now the preferred choice. When lowered, the safety curtain is designed to seal the backstage area from the auditorium by forming a wall, isolating the public from the performance areas of the stage. However, stopping the spread of fire is not its only use; it is a system to minimise smoke getting into the auditorium, which in turn stops panic, allowing a safe egress by all.

Early safety curtains, when lowered, came straight down to the floor, killing one or two unsuspecting performers. Modifications were made to the lowering systems. Instead of lowering straight to the floor, the safety curtain now stops about 0.7 metres above the floor. This allows any performer to get out of the way or to be assisted, if knocked unconscious by the weight of the safety curtain hitting them, before fully reaching the floor.

By law, if fitted, the safety curtain has to be lowered during a suitable intermission to prove to the audience that it is working.

Stage Floor

Every stage has one, and it may be the most obvious but overlooked piece of stage machinery. The stage floor is not just a surface on which to perform; it is an integral part of the machinery of the theatre.

Theatres are expensive to build and run. Away from the capital, many towns may have only one stage on which to perform. Filling the seats in these venues requires that the public be offered a wide range of different performance arts. Each will have their unique demands on the stage floor.

From an auditorium, only a part of the stage floor may be seen - normally most is masked from view of the audiences. To each side of a stage are areas called the 'wings', where performers await their entrances and scenery is stored. When sliders5 are fitted, the wing area will have to be at least half the width of the visible stage size. Behind the stage back wall, or 'cyclorama', may be another large area used to store whole scenes.

Stages in some theatres have a raked stage - the stage floor is higher at the back than at the front, improving the illusion of greater depth when using 3D sets. Such stage floors may be precarious for actors, and totally impracticable for dance performers, who require a flat sprung stage6.

Generally, flat stage floors allow the maximum range of performances and mechanical enhancements, for use before and during the performance. Large musical productions with long expected runs will often take out the theatre's stage floor and replace it with a purpose-built stage floor. For shows like Mutiny, where a ship was able to be raised and rotated in full view of the audience, this special stage made up a large part of the pre-production costs.

Touring productions will often bring with them a production-specific stage floor called a 'deck', which is laid on top of the permanent stage.

Think no more of a stage floor as platform with entrances to the side or back of the stage. Actors may appear or disappear though sections of the stage floor, scenery may be rotated, lifted or slid into position.

Stage Floor Machinery

If scenery is lowered into place from the fly tower above, scenery may also rise from below the stage floor. The stage floor is not one continuous floor, but several sections of differing sizes.


Large movable sections of a stage floor that move vertically are called an 'elevator'. Each elevator may cover the full width of the stage and be up to two metres in depth, able to be raised higher or lower than the normal level of the stage floor. Elevators may also be called 'lifts' or 'bridges'.

One use of a elevator is the changing of a set. Scene changes are first started by lowering the elevator section beneath the stage. Out of sight from the audience, scenery is placed on the floor and then the elevator is raised back to stage level.

Single floor elevators have the disadvantage of leaving, during setting and placing the new set in place, a huge hole in the stage floor. To fill the hole in the stage, two 'sliders' may be slid under the stage floor.

An enhancement of the single floor elevator is a elevator with two floors. One setting is placed on the normal stage floor, another is below the stage, when the setting is to be changed the elevator is raised, revealing the new set. When several double floor elevators are used one in front of the other, large sets may be changed in front of the audience.


Smaller sections of the stage floor just large enough to allow a performer to appear or disappear are referred to as a trap.

Simple traps may be nothing more than a section of floor that is lifted up or lowered, as in the 'grave trap' with some steps to the under stage area. Usually beneath a trap opening is some form of elevator, on which a performer may be slowly raised or lowered. Like the larger elevators, a single slider may be slid beneath the opening for the trap, and lifted to form a level stage floor, when the elevator floor is lowered.

Sometimes actors need to appear quickly, as in the pantomime7Aladdin, where, with a puff of smoke, a genie appears as if from a lamp. Victorian theatres used the star trap. This must be the most spectacular - and possibly the most dangerous - entrance a performer must ever make.

Star traps consist of a permanent stage floor, made up of several triangular sections of flooring meeting at the centre, which may be lifted, but naturally fall flat. Under the stage is a elevator using counterweights that are heavier than the weight of the performer.

To make the impressive entrance, the elevator platform is first lowered, at which point a brake is applied, to stop the counterweight falling. The performer steps onto the platform. On cue the brake is removed allowing the counter weights to fall. The performer is thrust through the star trap floor. When the platform hits the highest point the performer leaps upward clearing the trap floor sections, which then falls back info position at floor level. With a puff of smoke the illusion is complete.


The largest and possibly the most versatile piece of stage floor machinery must be the 'revolve'. It is capable of allowing scenery to be brought into view of the audience, or of providing a treadmill-effect, allowing actors to walk while remaining at the same point of the stage.

A circular section of floor is made, which is fitted into a recess of the stage and able to rotate. This is the most basic of revolve. The world famous London Palladium had a twin revolve, seen each week at the end the television variety show Sunday Night At the London Palladium. It was removed for the production of Chitty Chitty Bang Bang. Each section was able to rotate in opposite directions and to be raised like a elevator to different heights.

Like the two-tiered elevator, it is now common to have a two tiered revolve, commonly called a 'drum revolve'. A fine example of this type of revolve is in London's Olivier Theatre, part of the Royal National Theatre complex. It can be used as part of the production by turning, or used as a circular elevator. The stage is divided into two sections with an individual elevator able to raise scenery into position and then rotate it into view. Whereas the elevator may have sliders to fill the missing part of the stage floor, the drum revolve may be fitted with a disk section to fill the empty space when a floor is lowered.


When it is not possible to use lifts or revolves, large sets may be moved into place on the stage by use of 'trucks'.

Trucks are small stages fitted with wheels, on which a section or small set is placed. It may be guided into the correct location by means of small tracks built into the stage floor or by stagehands.

Very large set components may be fitted with air casters8. This method of moving scenery is usually used for positioning sets during scene changes.

Each show will require some special contraption to achieve an effect. For example, the original production of Aspects of Love used the theatre's original stage treadmill. Production, however, ceased using it due to an accident. Many are designed for a specific show. The Witches of Eastwick designed a three person flying rig that allowed cast members to fly above the audience. Some use new ideas, and up to date technology; others older ideas and technology.

Mechanical Power and Control

Power to move stage machinery has changed over the years. Originally human muscle power drove all the equipment, by means of ropes and various simple machines.

Hydraulic motors and pistons are ideal for use in theatres because they are powerful and run quietly. In London, several theatres had their hydraulic power provided by the London Hydraulic Power Company until the Company's demise in 1977.

Electric motors are now the most common form of method to power stage machinery. Computers are also extensively used to control all the stage machinery as they allow repeatable accurate timings vital for any musical production.

No production is fully automated - there is always an operator co-ordinated by the stage manager to control the various pieces of stage machinery. From the control position the operator cannot see all the functioning parts. Sudden starting or movement may cause accidents!

The use of computer systems or remote control require a system to stop an item of machinery in case of an emergency to be fitted. Emergency stops, 'e-stops', may be operated manually or automatically by sensors, stopping operation of the mechanism or bringing the whole show to a halt.


Whatever type of show is performed, actors are still the driving force of a performance. Spectacles are the icing on the show's cake.

1The RSC is based in Stratford, England.2First built 1599 destroyed by fire 1613 rebuilt, closed 1642.3To fly scenery is to raise scenery into the fly tower.4An opening in a wall into which the audience looks.5A temporary stage surface slid into position under the normal stage floor.6Floor that assists the dancer to jump higher, and reduces impact on landing.7Traditional British production style of performance, usually performed during the Christmas season.8 The bottom of the truck is raised from the floor by air pressure, which allows easy movement.

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