Abstract: A dishwashing machine has a single motor pump unit, including a circulating centrifugal pump and a peripheral outflow drain pump mounted on a common shaft of a reversible drive motor to alternately deliver a washing fluid to and drain fluid from the dishwashing machine. The two pumps are connected by openings in their respective pump chambers communicating with an annular chamber between the two pumps. The annular chamber has a vent fluidly connecting the chamber with a washing water circuit of the dishwashing machine. Preferably the annular chamber has an impeller therein mounted on the drive shaft of the motor, forming a further centrifugal pump with the annular chamber.

Abstract: A wash tub for a dishwasher has a rectangular cross section and houses a spray arm rotatable about an axis adjacent to the center of such cross section. Larger side walls of the tub are provided with recesses capable of receiving the end portions of the spray arm during rotation thereof. The length and washing effectiveness of the rotary spray arm are increased.