Abstract: A refrigeration system generally including a compressor, a condenser, an expansion device, and an evaporator. A refrigerant expansion tank is connected to the suction side of the compressor to vary the charge of refrigerant in the refrigeration system. Preferably, the expansion tank adds additional refrigerant to the system only after it has reached, is near, or at least is approaching, its operating point. The additional refrigerant is removed from the refrigerant fluid path and contained within the expansion tank when the refrigeration system is turned off.

Abstract: An impact printer has a print band moving longitudinally around pulleys with one side of the band moving in contact along a rigid platen and the other side having engraved characters presented along a print line of a print medium (e.g. paper and ink ribbon). The leading edge of platen is squared off (e.g. sharp) to scrape contamination off the band. A row of hammers impact the print medium against the band between the hammers and an impact surface of the platen. The impact surface of the platen contains multiple longitudinal grooves which start slightly back from the leading edge of the platen and which prevent increased friction force between the band and platen from occurring as the band wears the platen impact surface smooth.