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..

Abstract: A shell for a hermetic compressor unit, the shell having a top section or dome, and a bottom section, the dome having a unique shape which gives enhanced capacity for absorbing and attenuating structural and fluid transmitted wave energies emanating from the unit at wave frequencies of between 1,000 Hz and 2,000 Hz, while reducing total operating noise of the unit, the dome being formed of sheet metal and having a generally inverted cup-shaped configuration with generally cylindrical sidewalls and a top wall having a central portion surrounded by a peripheral portion, wherein the sidewall taken in a generally axial direction is substantially straight, wherein the central portion of the top constitutes from about 40 to about 90% of the total area of the top and has a generally hemispherical configuration on a mean radius of from about 6.5 to about 10.0 inches as measured from an origin point O.sub.