Abstract: A rotary drive apparatus includes a housing having a housing hole defined therein, a cylindrical rotor being disposed in the housing hole, a working fluid passage through which a working fluid for applying a fluid pressure to one end face of the rotor flows, a motion limiting unit configured to limit motion of the rotor toward another end thereof, and an output shaft configured to extract rotary power of the rotor out of the rotary drive apparatus. A predetermined gap for the working fluid to flow therethrough is created between an outer circumferential surface of the rotor and a wall surface defining the housing hole.

Abstract: Twisted leaf shaped ceiling fan blades for low, medium and high speed operation of less than approximately 250 rpm. The novel blades twisted blades can be configured for 52?, 54?, 56?, 60? and 64? diameter fans, and have less blades (3 for example) than conventional flat type bladed fans having 4, 5 blades and have greater air flow and less power draw results than the conventional flat 54 inch fans. Any of the novel twisted blades of 48?, 52?, 54?, 56?, 60? and 64? can be run at reduced speeds, drawing less Watts than conventional fans and still perform better with more air flow and less problems than conventional flat type conventional leaf shaped blades.