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fans, used on larger models, include hollow GRE (glass-
reinforced epoxy) blades and epoxy-coated cast iron hubs.
Blades on both fan types are adjustable in pitch, so you can
take full advantage of rated horsepower or adjust the pitch
to compensate for unusual job site restrictions. The true
airfoil blades, designed specifically for cooling towers, offer
efficient, quiet operation and long service life.
Mechanical Equipment
You’ll receive a 5-year warranty against failure of any
mechanical component in the fan drive system (except the
motor, which is warranted by its manufacturer).
The Marley Geareducer speed reducers used in the
Sigma line contribute a long record of dependability, long
service life, and low maintenance to this assurance of
reliability. Their designs meet or exceed the requirements
of CTI STD-111 and AGMA Std. 420.04. We run-in every
Geareducer unit under load prior to shipment to make sure
that it will operate properly on your tower.
Housings are gray cast iron. Gears are high-strength,
case hardened alloy steel. And all bearings are tapered roller
bearings. A variety of available horsepower capacities and
reduction ratios lets us choose the optimum Geareducer
model and fan speed for your job. Service factors are always
at least 2.0 as applied.
Splash-type lubrication and integral cooling fins preclude
the need for maintenance-intensive oil pumps and coolers. A
constant oil bath or flow lubricates every bearing in forward or
reverse motion – at full or half speed.
All Marley Geareducer assemblies are right-angle type
with motors located outside the tower’s saturated airstream.
A galvanized steel lube line runs from the Geareducer unit
to a standpipe near the motor on each cell, so you can check
oil level and change or add oil while standing on the fan deck.
All Sigma Series 1000/1200 towers offer the benefits of
adjustable pitch propeller type Marley fans. The H-3 series
fans normally used on smaller models incorporate cast
aluminum blades and machined aluminum hubs. HP-7 series
Fans operate inside structural GRP (glass-reinforced
polyester) eased-inlet fan cylinders designed and applied to
maximize fan performance. Cylinder height varies from 3'-5"
to 7'-0", depending on fan diameter. Cylinders less than
6'-0" tall include galvanized welded fan guards. (See Access
and Safety on page 7.)
Marley-manufactured driveshafts transmit power
from the motor to the Geareducer assembly. All Marley
driveshafts include 304 stainless steel tubes with welded-
on stainless steel flanges and bonded neoprene flexible
elements to transmit torque. Marley driveshafts are full-
floating assemblies with non-lubricated flexible couplings
on each end. Their tolerance to misalignment and torsional
shock is unequalled in nonspecialized units. All Marley
driveshafts are dynamically balanced at the factory to
minimize operating vibrations.
Welded unitized hot-dip galvanized steel supports
maintain alignment throughout the mechanical equipment
system. Marley torque-tubes provide superior strength and
stability. Their cylindrical shape also keeps operating costs
down by minimizing airflow restrictions and reducing air
turbulence in the fan entrance region.
/ Construction and Components /