2.3.1.2
Floating Group Doors
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NOTE: Consider visual appearance when using the
anchored or wraparound cable system. The cables
used to move the door leaves are exposed to view.
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Each group of three or more leaves shall have a separate, traction-drive
operating unit located in each end leaf of the floating group doors, which
drives one or more wheels of the end leaf, and a wraparound cable system on
the intermediate leaves coupled to each end leaf; or an interleaf pickup
system. Movement of either end leaf shall allow stacking and unstacking of
the other end and shall also allow intermediate leaves to move in concert.
The group of leaves traveling abreast may then be positioned as desired in
the opening. Provide necessary cables, fittings, cable sheaves, housings,
guards, pickups, brackets, anchors, and miscellaneous hardware.
2.3.1.3
Anchored Group Doors
Each group of leaves shall have a traction-drive operating unit located in
the lead leaf of the group and driving one or more wheels of the lead leaf.
[The leaves in each group shall start to move at the same time and arrive
at their fully open or fully closed positions simultaneously]. Provide
necessary cables, fittings, sheaves, housings, guards, pickups, brackets,
anchors, and miscellaneous hardware.
2.3.2
Operating Units
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NOTE: Delete "lead" for individually operated
doors. Leave in for group doors.
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Each operating unit shall move its [lead] leaf at a speed of approximately
20 meters 60 feet per minute at zero wind load conditions and to be
operable up to and including a maximum wind load of 0.4 kilopascals 8
pounds per square foot. The operating units shall consist of either a
separate motor and gear reducer or a gearhead motor, high-speed shaft
brake, and necessary roller chains and sprockets. The systems shall be
provided with overload protection for the drive units and a means for
emergency tractor towing operation.
a.
Motors shall be single speed, squirrel-cage type of sufficient
size to operate the leaves under zero wind load conditions at not
more than 75 percent of their rated capacity.
b.
Gear reduction units shall allow a reversal of effort through the
gears without damage to the units.
c.
Operating mechanisms shall be covered on the interior of the leaf
by a hinged 1.5 mm thick 16 gage flat steel cover.
2.3.3
Braking Systems
Braking systems shall be designed to ensure stoppage of the leaves under
normal, dry rail conditions within the safety edge overtravel limit. The
braking systems shall be either a magnetic, spring-set, solenoid-released
brake or hydraulic type. Provide a hand release to release the brake when
SECTION 08342
Page 16
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