Centrifugal Fan Motor Sheave

In a belt-drive centrifugal fan system, the drive ratio between the motor and the fan is determined by a single component, which is called the motor-side sheave. The RPM at which the fan will spin, the load on the belt and how stable the drive will be all depend on this small part. But if it is sized incorrectly or slightly misaligned, it can silently cause serious damage to the entire system. The small size of the Centrifugal Fan Motor reduces sheave belt contact. As a result, the belt slips under the pressure of the load and the motor's power is lost as frictional heat instead of airflow. If the sheave is oversized or misaligned, it silently adds additional vibration and radial load to the system. As a result, the life of belts and bearings is reduced long before any visible damage is noticed.

The correct selection begins by calculating the motor horsepower, target fan RPM, belt section used and center distance in relation to the sheave pitch diameter. Variable-pitch sheaves are used when fine-tuning or commissioning fan speed, because the desired speed can be easily obtained by turning its flange to change the pitch diameter. But for ultimate regular operation, the fixed-pitch sheave is the most reliable. It is completely stable and has no risk of loose flanges or setscrew backlash. Taper-bushing mounting is preferred over setscrew mounting in high-power or heavy-duty applications. Because it creates a much tighter fit with the shaft and it is also quite easy to open or close. After any Centrifugal Fan Motor Sheave installation, it is essential to verify alignment with a straightedge and set the correct belt tension. Because just changing the sheave doesn't finish the job; even the slightest misalignment is the most common cause of premature belt and bearing failure.