US Patent 7800262 Centrifugal drop fan and valve with sliding motor

A combined centrifugal fan and valve to exhaust air outside of a building when running and to prevent air from escaping when not running. The electrical motor design is to allow the rotating parts of the motor to slide along the motor shaft axis. The vertical position of the motor will allow the sliding capacity of the motor to utilize the weight of the fan, motor shaft and motor armature to hold the base plate of the fan tightly against the inlet opening when the motor is not running and lift the fan, motor shaft and motor armature when running by the magnetic forces of the motor windings.