Theatre Design & Technology - Feb 1967 - 24

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Fig. 5: Draw Curtain Indicator.

Indicators for Machinery Below Stage Level. The complex
machinery below stage level offers a wide variety of possibilities for the use of telemeters. Elevators, elevating stage
segments, revolving stages and wagons are often driven
from control boards located below stage level, so that in
most cases a simple scale located near the control board
is sufficient. However, when more than one element is to
be set into motion simultaneously, it becomes necessary to
have a central control board for which telemeters are an
absolute prerequisite. Linear scales are best suited for this
purpose as they allow the control personnel to immediately
determine the exact position of a piece of machinery at
any given point with the greatest ease and accuracy. Vertical elevation and tilting must be illustrated separately because of the construction of such telemeters. To comply
with safety regulations, signal lights can be connected to
the various elements in order to signal the locking in place
or coupling of two wagons.
Multiple telemeters for elements which move vertically above
and below stage, such as orchestra podiums and stage
platforms, are necessary as in the case of light bridges and
portals. Here too, the various scales should be arranged so
that stage level is located at the same point on each scale.
In such cases it is advisable to set the clock-type fine adjustment scale so that one complete rotation is equal to one
stop in the total range of movement and not, as is normally
the case, equal to a finite distance, as a yard or a foot.
The movement of wagons is normally shown on a horizontal
linear scale located at the stage manager's station or at
the control board. It is especially difficult to set up any sort
of standards for telemetering wagons. The number and position of the wagons depends on the construction of the
stage area; thus these problems can only be solved for each
special situation. Often one can simply use the stage floor
plan drawn to scale for the indicator scale. The design of
this type of meter requires special planning and usually demands special construction. To illustrate this point one need
only to consider the following situation: A wagon moves
from stage right to stage center at stage level and is there
lowered by an elevator over which another wagon from upstage or stage left is superimposed. For telemeters capable
of illustrating functions as complicated as this, it is necessary to plan and design specially-constructed scales which
meet the requirements of equipment firms as well as those
of the client.

Fig. 6: Revolving Stage Indicator

Many theatres are equipped with revolving stages as well
as wagons, particularly for operettas and musicals where
fast scene changes are important. Here it also is possible
to equip the control mechanism with a telemeter. The best
type of scale is a square faced panel with a rotating clocktype disc (Illustration 6). A stationary arrow at the bottom
of the scale points toward stage center from the audience.
The actual position of the elevators and trap doors can be
painted on the disc in scale. The edge of the disc is
marked with linear measure or degree segment lines. For
larger stages the rate of accuracy of + - 1 % of the actual
distance converted onto the segment scale is often insufficient, thus making it necessary to install a fine adjustment
disc next to the main disc. On the scale of the fine adjustment meter an actual distance of 100 cm is divided equally
over all 360 0 of the fine adjustment disc. In this manner it
is possible to achieve a rate of + - 1 % regardless of the
actual size of the revolving stage. This of course only holds
true as long as the actual circumference of the revolving
stage has an even number of meters total. Otherwise the
fine adjustment scale would move on to the next full meter
while the stage itself would not have completed a full
revolution. Thus if the actual revolving stage does not meet
this requirement it will be necessary to figure an arbitrary
value for the fine adjustment scale.
Designing and Installation. In general the same companies
that have delivered and installed the stage machinery will
also install the corresponding telemeters. Many electrical
firms connected with the design and installation of electrical
equipment in theatres will also do this. These firms are
normally in the best position to determine which particular
connection between the data-transmitter and the piece of
machinery is the most advantageous. The accuracy of the
scale is largely dependent on the type of coupling used. In
order to avoid as many mechanical errors as possible, the
following rule of thumb is quite helpful: The data-transmitter
for a telemeter should be connected to the piece of machinery as "close" and as "tight" as possible. For this
type of coupling either chain drives or flexible shafts will
be used, according to the type of coupling. Because every
theatre is completely different it is very difficult to install
telemeters from "off the rack." It is equally difficult to establish a general set of rules for their installation. On the
other hand the manufacturers are in a position to design
systems tailored to the needs of a particular theatre, no
matter how unusual they may be.

ruillD THEATRE DESIGN AND TECHNOLOGY

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