Blade pitch is the manufacturer's recommended degree angle of attack from the blade's horizontal axis and is the optimum angle that will load the motor to provide the amount of air required to perform the cooling specified. Pitch angles on all Hudson fans are set approx. The protractor must be of a type that reads angles in degrees from horizontal. Blade tracking requires lifting of the blade tip during installation to ensure that all blades are in the same horizontal plane with the other blades in the assembly. Blade tracking is set at the same time as pitch.
Poor tracking is one of the major causes of fan vibration.
The fiberglass seal disc is installed on top of the fan hub and helps prevent hot air recirculation back through the middle of the fan system. The seal disc adds approx. The inlet bell consists of several segments of formed fiberglass that are installed below the fan to shape the air flow and reduce turning losses due to the abrupt corners in fan rings. This shaped air flow improves air distribution and fan efficiency. Excessive or irregular tip clearance causes uneven blade tip loading, reduced air draw, hot air recirculation and repetitive vibration.