Abstract: A table suspended from a room ceiling has a table top that is positionable between a retracted first position against the ceiling and a second position extended from the ceiling toward the floor. Extension and retraction occur through a pivotal arm assembly. The arm assembly is controlled by electric or manual powered drive mechanisms. The drive mechanisms are enclosed in a modular housing that is manufactured to interchangeably accept either the electrical or the manual drive mechanisms. The suspended table includes a table top that is rotatable about a vertical axis.

Abstract: A table suspended from a room ceiling has a table top that is positionable between a retracted first position against the ceiling and a second position extended from the ceiling toward the floor. Extension and retraction occur through a pivotal arm assembly. The arm assembly is controlled by electric or manual powered drive mechanisms. The drive mechanisms are enclosed in a modular housing that is manufactured to interchangeably accept either the electrical or the manual drive mechanisms. The suspended table includes a table top that is rotatable about a vertical axis.

Abstract: A rotary, Perkins tube heat exchanger for processing hot contaminated gas flows emanating from appliances such as laundry driers, grain driers and the like. The case of the heat exchanger is located relative to the rotor so as to lie in the gas flow boundary layer established by the latter. The case is provided with a boundary layer purge port in the hot gas chamber. An airfoil extends inwardly from the case into the gas flow boundary layer. It causes increased local turbulance in the boundary layer gas. It also diverts a predetermined proportion of the boundary layer gas and its burden of contamination products out through the purge port. The boundary layer airflow cleans both the interior of the case and the rotor, even through the rotor is characterized by the presence of a multiplicity of small openings. The device thus is rendered self-cleaning and may be operated for extended periods of time without buildup of contaminants within the heat exchanger case.