How-Tos, Take Two: Air-Braking Systems for the Commercial Theatre


In Terry Saterne's 1975 Theatre Crafts article (“Shoptalk,” May/June 1975, p. 48), he states, “One of the reoccurring problems in the theatre is how to secure scenery to the stage quietly, quickly, and be able to move or shift scenic units just as quickly.” The article goes on to describe an effective if a bit awkward hydraulic caster system that was devised for moving large repertory sets at the Guthrie Theatre. In the last 25 years this situation has not changed much in the commercial theatre, especially in the area of larger prop and furniture units.

Automation of scenic units is now so commonplace that we have come to expect it. When a winch-driven automated scenic or prop unit comes to a stop, it is its own braking system. However, smaller prop units, especially those that stand alone without an automated pallet, are harder to stop effectively. Wedges and cane bolts are ineffective or awkward. Step-on stop hardware just doesn't work; pianos slip and sofas slide.

With the exception of the larger regional theatre companies, most commercial producers have been reluctant to invest the labor and equipment expense in equipping prop and furniture units. Fearing that an expensively outfitted piece might get cut or changed while in the staging process, we have resorted to the old tried-and-true methods of actors and technicians setting and striking. Most directors lament seeing actors working to get their furniture in place and technicians carrying furniture in blackouts.

The principal reason that regional theatres have led the way in this area is that although their budgets may be smaller than Broadway and touring productions, regional theatre companies keep a stock and recycle parts. The expense of automated stop mechanisms can be shared by several shows. This is almost never the case on Broadway.

However, a change may be coming, if the current Broadway season is any indication. Air-actuated cylinders are used in the current production of 42nd Street to stop twin grand pianos, which must straddle the edge of a revolving turntable. In the upcoming production of The Sweet Smell of Success, beds, sofas, and pianos all carry air tanks and cylinders with either stop rods that lift the units off their wheels or brake the casters from rolling. Brakes are applied by means of a switch that can be located anywhere on the unit. Units can be moved easily and utilize triple-swivel casters. The current production of The Graduate has chosen to use this technology to move two different-sized bed units that double and triple as five different beds (the headboards are switched and the bedding is redressed).

The pneumatic system used at Prism Production Services for stopping prop units consists of three major components:

  1. An air cylinder with a high torsional load capability that generates approximately 180lbs in lift. This cylinder component can either be attached to a special locking swivel caster or to a rubber pad, which will lift the unit off its wheels. The swivel caster option is superior due to its ease of installation and lack of visible motion when engaged and disengaged. The brake, which stops the swivel caster, does not raise or lower the unit at all.

  2. A mechanical air switch. This could be swapped for an electronically actuated air switch if remote operation is needed.

  3. A storage tank component, either a refillable air tank, which would require an onsite air compressor, or commercially supplied bottled air. Typically, tank pressure would range between 100 and 150psi. Actual output pressure for cylinders should be regulated between 40 and 48psi.

Why the sudden demand for air-powered brakes? One reason is that the technology has improved. The hardware is compact, dependable, quiet, and worth the investment. Sometimes a winch-driven automated unit is not appropriate for reasons of budget or practicality. When the same prop gets used in a variety of locations and gets moved à vista, then an air brake makes sense. For the commercial theatre, this is a cost-effective way to stop a moving unit anywhere onstage without having to be locked into winch track location so that staging can be changed as necessary.