Abstract: A synchronous air blower, a HVAC system and a HVAC rooftop unit is disclosed. In one embodiment, the synchronous air blower includes: (1) a permanent magnet motor having a motor shaft with a first cogged sprocket attached thereto, (3) a fan having a fan shaft with a second cogged sprocket attached thereto and (4) a synchronous belt coupled to the motor shaft and the fan shaft via the first and second cogged sprockets, the synchronous belt having teeth configured to mate with the first cogged sprocket and the second cogged sprocket.

Abstract: A wrist pin for use with a piston of a refrigeration compressor unit, wherein the wrist pin is to be mounted on a piston and non-rotatively affixed thereto, the pin having a longitudinal axis, a round cross-section and a uniform diameter over substantially its entire length to provide a peripheral journal surface adapted to be mounted within and juxtaposed the bearing surface of a wrist pin bore of a connecting rod for rocking motion within the bore, one or more oil transport grooves in the journal surface circumscribing the same within a longitudinally central region thereof, a generally longitudinally extending recess in the journal surface extending across the one or more grooves and to either side thereof within the region, the region of the journal surface being dimensioned to lie totally within the wrist pin bore of the connecting rod, the recess laterally encompassing an arc angle of from about 6.degree. to about 30.degree..