Abstract: A ventilation fan structure has a fan blade-motor portion and a shroud portion independently affixable to the ceiling to reduce noise levels, improve aerodynamic efficiency, and facilitate installation. A mounting member is affixable to ceiling joists, one of which spans an opening in the ceiling for the fan structure. The drive motor and associated fan blades are mounted on the mounting member. The shroud surrounds the ceiling opening and embraces the fan blades. The mounting member extends through the shroud in its attachment to the joists.

Abstract: A ventilation fan structure has a fan blade-motor portion and a shroud portion independently affixable to the ceiling to reduce noise levels, improve aerodynamic efficiency, and facilitate installation. Mounting members are affixable to ceiling joists spanning the opening for the fan structure. The drive motor and associated fan blades are mounted on the mounting members. The shroud surrounds the ceiling opening and embraces the fan blades.

Abstract: A trash compactor has a rotatable lead screw and stationary nut for raising and lowering the compacting ram by rotation of the screw. A housing surrounds the nut for preventing rotation of the nut with respect to the screw while permitting limited pivotal movement of the nut with respect to the housing responsive to eccentric compaction forces applied to the compacting ram. The housing is distortable for the same reason and to permit absorption of shocks arising from compaction. The nut may be formed of a self-lubricating plastic. The drive mechanism may be used in a trash compactor having an extensible linkage of the scissors jack or lazy tongs type in which the lead screw is journalled in one of the intermediate junction points of the linkage. The housing containing the nut is located at the other of the junction points so that rotation of the screw extends and retracts the linkage.