Patent ID: 7472714

Claim:
A dishwasher comprising: a tub including at least bottom, rear and opposing side walls that collectively define a washing chamber; a dish rack mounted within the washing chamber, said dish rack being adapted to support dishware during a washing operation; a wash pump for delivering a washing fluid to at least one wash arm in the washing chamber during select portions of the washing operation; and a drain pump for expelling at least a portion of the washing fluid during select portions of the washing operation, said drain pump including: a pump housing having an inlet portion and an outlet portion; an impeller including a central hub and a plurality of vanes, said plurality of vanes extending radially outward from the central hub; an apertured plate positioned at the inlet portion of the pump housing; a chopper assembly having a pivoting blade member positioned adjacent the apertured plate; and an axially sliding drive mechanism having a first end mounted within the central hub of the impeller and extending through the apertured plate to a second end which is drivingly connected to the blade member of the chopper assembly wherein the axially driving drive mechanism includes a guide bushing including at least one of an axially projecting key member and a keyway, and the axially sliding drive mechanism enables the blade member to shift axially relative to the apertured plate during operation of the dishwasher drain pump.