75. Operating
Equipment:
The normal operation
of the curtain shall be the raising and lowering of the curtain electrically by an
electric hoist located above the gridiron.
Hoist shall be connected by a roller chain to a sprocket on one of the
head blocks. The hoist shall have a five
(5) horse-power elevator type motor directly connected to a machine cut
worm-geared speed reducing unit, mounted on a rigid cast iron base. The reducing unit shall have a steel worm and
a bronze gear enclosed in an oil tight housing.
On the slow speed shaft there shall be a heavy friction clutch. The emergency lowering of the curtain shall
be by gravity obtained by under-balancing the curtain with reference to
counter-weights. Emergency control
stations shall be located at each side of the proscenium opening at the stage
floor and there shall also be at least three (3) quick acting heat-operated
release devices for automatically closing the curtain.
76. For checking the free lowering of the curtain
there shall be an oil dash pot not less than five (5”) inches in diameter,
cylinder machine bored and fitted with plunger and rod with a sixteen (16”)
inch sheave with necessary cable for checking the curtain six (6’0”) feet above
the stage floor and then allow the curtain to lower slowly to the stage
floor. This Contractor shall furnish the
push buttons, limit switches, control panel and the motor but do no wiring at
the building. There shall be one (1)
station located as directed for the normal operation and at the two (2)
emergency lowering stations there shall be a sign giving instructions for
lowering the curtain. To these signs
there shall be attached by chains, knives for cutting the release lines.
77. This curtain
shall comply with all the requirements of the City, State and Board of Fire
Underwriters.