Theatre Design & Technology - Oct 1969 - 13

Let me assume a common situation: A box
set and an upstage electric pipe that must
be rigged before the set is made because
the length of the pipe is greater than the
opening of the set. Thus, accessibility is
rendered difficult. Why not rig a pipe section to fit inside the set? This is easily
p,ssible in our Playhouse not only with the
winch, but using counterweight as well.
It is thus possible to use the theatre in a
standard fashion, that is, counterweight sets
parallel to the proscenium with thewinch reserved for spot I ine applications for ladders,
booms, chandeliers, etc.: or the winch can
become the dominant system which provides
for raked or obi ique hanging and the counterweight handling that which remains parallel remembering that it is possible to use
only the actual lines necessary per set.
Essentially, this rigging system does most
of the things that were, and still are, accomplished by the expanded rope system
such as at the Orottningholm. In short, the
system is fast in set-up and strike, is capabl e of varying weight loads and is flexible.
This flexibility truly provides for the designer
a remarkable degree of freedom, but it also
requires a rather thorough understanding of
this type of combination rigging so that it
works for the design rather than against it.
When I joined the staff at U.C.L.A. the
theatres were about six months old, and
several conditions existed which made the
operation of the winches anything but desirable. Our major concern was accuracy,
reliability and most important-safety.
Accuracy of the winch was not good in our
early days, for the brake and its adjustment
were far from meeting optimum needs. As a
matter of fact, the retrimming of I ines in
the rope system was more reliable than the
winch. When a motor moved to trim and

stopped, it would coast through the brake.
Of course, loss of trim would result. If
this motor was required to move more than
once during a performance, then the loss of
trim was magnified. The situation was impossible when several motors were grouped
together. Hence, the brakes were re-worked
and an adjustment procedure was established. Since then, we have had few problems with the brakes, and a once-a-year
program of inspection has been implemented
to insure correct functioning of this aspect
of the device.
Exposed relays in the console also caused
operational problems. Since any stage has
varying quantities of dust and other airborne materials, the contact surfaces soon
began to have "make sure" difficulties. In
addition, the physical location of the main
relay bank was so close to the patch cord
counterweights that rapid movement of an
individual patch cord on occasion caused its
weight to make contact with one or more
relays. This would sometimes damage the
contact fingers which in turn caused intermittant functioning. Thus, the operator at
the console was never quite sure if a particular control channel would function-an
uncomfortable situation, indeed. Ultimately,
the entire relay bank was relocated and a
sealed-type relay was used. To date no
problems have occurred with the relays.
But the major problem was with the failsafe provision. The console has a panic stop
button which would stop all motors, but
this circuit had to be energized by the
operator. Under performance conditions it is
not always possible to have the visibility
that one would prefer. In addition, should
something fail in the telemetry itself, the
motors would continue to run, and this is
most assuredly dangerous.

THEATER DESIGN AND TECHNOLOGY

After the original installation and checkout,
an adjustable limit switch was installed on
each winch unit. If engaged, the condition
termed "grid collision" would exist. However, this did not protect down travel and
a 200 pound chandelier operating on telemetry stove into the stage floor during a
scene shift cross fade. Subsequent checkouts showed the tel emetry to be rather erratic.
Two possible conditions came to the fore
at this time: one was the possibility of
internal malfunction in the counting aspect
of telemetry control and the other was a
failure in the transducer itself.
It was at this point we realized that the
limit control telemetry was not feasible. It
was then all too apparent that a fail/safe
network had to be incorporated into the system, for by this time the system was declared hazardous. We had no other recourse
but to stop all use of the winch on telemetry, which effectively reduced the winch
to a spotted, deaded type of rigging. This
was a sad day for all, but we agreed that
until we could feel reasonably confident in
the system this should be its operational
limit.
In the interval between then and now, most
of the major problems described have been
or are in the process of being corrected.
We are now installing the following failsafe units. First, a limit switch which will
offer protection in both modes of travel.
This switch is a Square-O unit. Series
A-Lu type, which allows for breaking the
fail-safe circuit in either the up or down
direction. There will be two adjustable disc
trip dogs, one for up, one for down.
The winch block spotting procedure will be
as follows:
When the new position of a
given block is determined, the motor is
driven down till the tally weight is at stage
floor level. The weight is then removed,
the line taken up to the grid and the winch
block moved to its new position. The line is
then re-run down to the stage floor, the
tally weight replaced and the motor run up
to a point with its weight safely under the
grid floor. At this point, the upper limit dog
is set. This is done for all motors, regardless of whether or not the motors move
during the production. The reason for this
is that it is otherwise possible on a production strike to forget which motor was
doing what. When clearing the lines, in
that event, it would be possible to cause a
grid collision if the up limit had not been
set.
The setting of the lower limit is done after
the rigging of the particular unit is completed. This limit setting is not intended to
be critical, but to work rather as a fail/safe
check on the telemetry.

Ground floor plan of theatre complex

The motors have an ultimate limit switch
for both "up" and "down" travel modes,
but its function is primarily to protect the
winch itself-not the variable operation.
It had been further stated by the manufacturer that the telemetry device would provide limit control. This was fine if the telemetry is fail/safe, but it is not.

OCTOBER,1969

Table of Contents for the Digital Edition of Theatre Design & Technology - Oct 1969