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There are two distinct types of mechanical operators suitable for use
with industrial sidewall windows the torsion lever arm type and the rack
and pinion type. Both consist of a worm and gear power actuating a
revolving horizontal pipe shaft. In either type the power may be
controlled by means of -
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A chain wheel with a continuous chain extending to within
2'-0" of the floor.
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A vertical pipe shaft with handwheel attached to the lower end
approximately 4'-0" above floor.
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A vertical pipe shaft extending to a mitre gear box
controlled by a handwheel or detachable crank handle at mitre gear box located
approximately 4'-0" above floor.
The above is common to both types of
operators and the following outline describes the principal difference and
respective advantages.
LEVER ARM TYPE
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Force is transmitted from horizontal
shaft to ventilators by means of malleable iron lever arms, and steel
connecting bar.
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Provides adequate control for short
runs, although lever arm design develops more torsional stress
in the horizontal shaft than that of rack and pinion design. Therefore, a
finer adjustment is required to obtain tight closing of ventilators
farthest removed from the power.
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This type of operator is most
economical for short runs of windows.
RACK &
PINION TYPE
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Force is transmitted from horizontal
shaft to ventilators by means of a reinforced pinion set screwed to the shaft
and a rack arm held in mesh with the pinion by a floating steel yoke.
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Provides very accurate control for
any length of run within table of limits. This design develops minimum
torsional stress and is most efficient type of operator.
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This type of operator is also most
economical for long runs of windows.
The gear
ratio for the 1400 series power is 20:1. The gear ratio for the 1800 series is
30:1.
Right angle transmission gears are furnished only with machine cut steel mitre
gears and enclosed in oil tight housing.
Crank or handwheel controlled mitre gear boxes are
available in either dust or oil enclosed types.
Chain wheel type powers are recommended for single
runs only. For multiple runs, that is parallel lines of operators located one
above the other and controlled from one station, use verticle shaft control
with handwheel at mitre gear box. In the latter case, use one power at each
horizontal shaft.
If chain wheel control is required for multiple
runs, use one right angle transmission gear box at each horizontal shaft plus
one power per group. Verticle shafting is required to connnect the right angle
transmissions. This arrangement should only be used when building conditions
make it impossible to use vertical shaft and mitre gear control.
Universal joints may be used to offset vertical
shafts. Degree of offset should never exceed 35 degrees.
Horizontal shafts at right angles to each other may
be controlled from a single power, provided that a right angle gear
transmission gear box is used at the junction. This arrangement should be
confined to short runs. Consult Home Office whenever necessary to use this
arrangement.
Generally, horizontal and vertical shafts are of
1-5/16" O.D. standard pipe coupled together with malleable iron or steel
sleeve couplings. Standard practice is to attach the lever arms or rack arms
to the hardware bracket located at the bottom of pivoted, top hinged and
projected down and out ventilators. Arms are attached to the top of
ventilators that are bottom hinged or projected up and in types only, or where
clearance for arms is restricted, such as in craneways, etc.
All shaft hangers are roller bearing type and
adjustable to compensate for variation in building construction. Hangers are
located at each sash mullion and intervals not to exceed 8'-0" on centers
along the walls should any occur between the extremities of the individual
runs of operators. |