Geareducer
The Marley Geareducer® has become the standard by which all other cooling tower fan speed reducers are judged. Numerous reduction ratios are available so that horsepower is applied at optimum fan speed. The specific Geareducer selection is based on fan speed and horsepower requirements up to 300 hp per fan.
Marley Geareducers are designed to meet or exceed the requirements of CTI (Cooling Tower Institute) STD-111 and AGMA Std. 420.04, and are run-in under load prior to shipment. Housings are gray cast iron (ASTM Class 20), heat-treatment stress relieved, and covered with two coats of epoxy-polyamide paint. Gears are high strength, case hardened alloy steel. All bearings are tapered roller bearings with minimum B10 service life of 100,000 hours. Service factors are at least 2.0 at applied horsepower.
All Marley Geareducers are right-angle type with motors located outside the saturated effluent airstream.
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. Lubrication is maintained in forward or reverse motion—at full or half speed. Geareducers on Class 600 towers are equipped with remote sight gauge and drain lines, which permit constant surveillance of oil level in each unit.
Driveshafts
Marley-manufactured driveshafts transmit power from the motor to the Geareducer. All Marley driveshafts are manufactured from either carbon fiber composite or stainless steel tubes with stainless steel flanges. Bonded neoprene flexible elements transmit torque and require no lubrication. Marley driveshafts are full-floating assemblies with flexible couplings on each end. Their tolerance to misalignment and torsional shock is unequalled in non- specialized units. All Marley driveshafts are dynamically balanced at the factory to minimize operating vibrations.
Unitized Support
The Marley torque-tube unitized support stabilizes the fan within the fan cylinder and maintains constant alignment between the motor and the Geareducer. It is a welded unit of large diameter pipe, heavy angles and plate, and hot dip galvanized after assembly. The large tube design locates the fan at its optimum operating elevation within the fan cylinder and provides excellent torsion resistance along all potential axes of movement. It is fastened to the wood structure through heavy wide flange beams. Formed retainers surround and contain the drive shafts.
In addition to superior strength and stability characteristics, the Marley torque-tube offers minimal airflow restriction in comparison to typical boxlike configurations. Its cylindrical shape also minimizes air turbulence in the fan entrance region.
