Abstract: A ventilation shutter has a frame forming the mounting structure for a plurality of louvers that are pivotably mounted so as to move between an open condition to allow ventilation air through the shutter and a shut condition. The ventilation shutter includes at least one connecting rod extending transverse the louvers and a plurality of cranks, where each of the louvers has at least one crank connecting the louver to the connecting rod such that pivoting movement of the louvers between the shut condition and the open condition is synchronized with up and down movement of the connecting rod. A permanent magnet couple interacts with the connecting rod and the frame to provide an active magnetic force that holds the louvers in the shut condition. An electromagnet couple interacts with the connecting rod and the frame to provide an active magnetic force that holds the louvers in the open condition.

Abstract: A fan assembly has a plurality of blades received on a rotatable hub and held on the hub with a retainment mechanism. The hub has a plurality of hub stations located thereon, each hub station having a plurality of radially extending hub cogs and a hub indexing mark. Each blade in the fan assembly has a blade end having a plurality of radially extending blade cogs configured to interface with the hub cogs. The blade end also has a blade positioning mark adjacent one of the blade cogs. The blade may be rotated with respect to the hub to a plurality of different orientations and still have the blade cogs mesh with the hub cogs.