103. This Contractor
shall furnish and install three light bridges of the drop open double type as
approved and shown on the drawings as bridges E, F, and G. These bridges shall be approximately
one-hundred and four (104'0") feet long and two (2'0") feet
wide. These bridges shall be made in
sections and shall have hangers of two and one-half inch by three-eighth inch
(2-1/2" x 3/8") iron. All hangers for the bridges shall be continuous
and curved across the top and bottom of the bridges so that battens of other
sets will not foul. There shall be two
(2) three inch by two and one-half inch (3" x 2-1/2") angle to carry
the upper floor. This floor shall be of
one-quarter (1/4") inch plate sixteen (16") inches wide and spaced
ten (10") inches apart. Two
(2'0") feet below the upper deck there shall be hung a lower floor of
one-quarter (1/4") inch plate.
These plates shall be ten (10") inches wide. From the lower floor there shall be suspended
a one and one-quarter (1-1/4") inch pipe batten to receive the strip
borderlights. The space between the upper and lower floor on the downstage side
of the bridges shall be enclosed with a heavy wire mesh guard.
104. On the upper
floor there shall be forged fittings to receive the hangers of the spotlights
and also a continuous batten, mounted on pillow blocks, fitted with crank arms
at the rods for tilting the spotlights.
The tilting effect shall be by an approved system controlled from the
stage floor. Above the upper floor, the
downstage side of the bridge shall have a one (1") inch pipe guard rail
with posts about five (5'0") feet apart.
On the upstage side there shall be a guard rail with stanchion posts
about three (3'0") feet apart.
105. These stanchion posts shall be connected with
the guard rail with cross fittings. On
the top of the stanchion posts there shall be a reducing fitting with set
screws to take a spotlight. On the lower
portion of the stanchion post there shall be a movable collar for lowering or
raising a swivel arm, which shall be fitted to receive spotlights. The swivel arm shall have thumb screws for
clamping arms into position.
106. This Contractor shall also furnish and
install Light Bridge
107. All light bridges shall be raised and lowered
by electrically operated counterweight sets.
Each set consisting of twenty-two (22) sixteen (16") inch machine
turned ball bearing loft blocks, one (1) twenty (20") inch machine turned
head block with separate grooves for each cable and one (1) idler tension
sheave machine turned for increasing the contact of the cables on the head
block. The electric hoist shall be
similar to that specified for the cyclorama and connected to the head block in
the same way.
108. Each bridge shall be hung on twenty-two (22)
three-eighth (3/8") inch cables, which shall be attached to the
counterweight frame by five-eighth (5/8") inch turnbuckles. The counterweight frame and tracks shall be
of similar construction to those specified for the Act Curtain.
109. This Contractor shall furnish the motors,
control panels, control devices and limit switches. All other electrical work shall be done by
OTHERS.
110. This Contractor shall furnish and provide and
install all necessary cradles, cables, loft blocks and sheaves for the proper
handling of the flexible feed cables between the gridiron and the bridges.