US Patent 8162073 Nailer with brushless DC motor

A device for impacting a fastener in one embodiment includes a drive mechanism configured to impact a fastener, a lever arm pivotable between a first position and a second position, and a motor including a plurality of permanent magnets mounted on a rotatable housing, the motor mounted on the lever arm such that when the lever arm is in the first position, the rotatable motor housing is isolated from the drive mechanism and when the lever arm is in the second position, the rotatable motor housing is positioned to transfer rotational energy to the drive mechanism.