Your gear drives can make or break the performance of your cooling towers. Gear drives should be inspected and maintained to prevent issues. The following are some common issues that arise when dealing with cooling tower gear drives, depending on their specific operations. It is important to know how to prevent these issues from becoming a problem by having regular maintenance and inspection schedules.
Single speed motor operated gear drives
Damage to the gear teeth is one of the main issues to look out for when it comes to single speed motor operated gear drives. Large torque spikes can often be a contributing cause of this type of damage. Energy is sent from the motor through the drive shaft. Once that energy hits the drive, torque is displaced and absorbed by the internal components of the equipment.
Different motors can limit the starting torque. Make sure the fan is not “windmilling” in a reverse direction before the motor starts up. Consider adding a non-reverse option to the gear drive, but only if icing is not an issue in your area.
Two speed motor gear drives
Damage to the teeth is also an issue with two speed motor operated gear drives. This equipment must have an adequate torque rating at both motor speeds. Use a time delay when switching from low speed to high speed to prevent any issues. As with a single speed motor, make sure that the “windmilling” effect is not present.
Variable frequency gear drives (VFD)
Variable frequency drives must be looked at more closely. These drives save money over time by reducing power consumption and prolong the life of the equipment by reducing wear and tear. If not set up correctly from the beginning, or operated correctly, these drives can have the opposite effect.
Common maintenance practices that improve gear drive operations
Inadequate gearbox lubrication is the largest issue related to gear drive failures in cooling towers. By scheduling maintenance and inspections, you can avoid drive failures and ensure proper lubrication.
A monthly inspection would likely consist of draining water off the bottom of the oil sump and filtering it through a particulate. A quarterly inspection may consist of analyzing oil samples, collecting vibration data, checking function of cutout switches, and checking the non-reverse device. During a semi annual inspection, your gear drive may get an oil change. Oil should be changed every 2,500 hours or 6 months, regardless of whether it is mineral or synthetic.
Although scheduled oil checks are more practical for larger operations, Amarillo Gear Service recommends filtering and changing oil based on its performance, regardless of operational hours. For a filtering option, please read more about our Gear Servicing Unit (GSU).