Spiral gyrator for washing machines

A washing machine comprising:

• a tub having a bottom and a substantially vertical wall for enclosing a space to contain wash,
• a gyrator having a base and a driving post, said base subtending a substantial portion of said bottom, said base having an outer circumferential portion and an inner upper portion shaped substantially as a frustum of a cone, the base of the cone being parallel with said bottom and said outer portion extending outwardly therefrom, said driving post extending coaxially upwardly from the truncated end of said inner portion of said base,
• a driving surface comprising a spiral ridge having one end positioned substantially circumferentially on the upper surface of said outer circumferential portion and extending from said one end gradually inwardly and upwardly in one circumferential direction on the surface of said inner portion of said base to said truncated end thereof and continuing in said one circumferential direction like an expanded helical screw thread upwardly about said driving post to an upper intermediate region of said post where said ridge gradually reverses in circumferential direction to form at least one helical turn of opposite direction near the upper end of said driving post, the ends of said driving surface having gradual and smooth contours, and
• unidirectional driving means connected to said driving post to rotate said gyrator about said axis thereof.