The lengths of the links comply with the condition: D͞B=B͞C. Link 1 carries roller a which slides along fixed slot b-b whose width equals the diameter of the roller. Point A of link 1, located at the distance A͞B=B͞D, moves along straight line x-x which is perpendicular to the axis of slot b-b. The points of handle d describe elliptic paths. The lengths of these paths depend upon the length of slot b-b.
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