Sliders 1 and 2 move along fixed guides a and b whose axes are perpendicular to each other. Points of link 3 describe ellipses with their centre at point 0 and with semiaxes whose lengths equal, respectively, the distances from the selected point to points A and B. The mechanism is equivalent to a mechanism consisting of two gears, 4 and 5. If gear 4 of radius A͞B is fixed and gear 5 of radius A͞B/2 is rolled inside gear 4 without slipping, then points of gear 5 describe the same ellipses as points of link 3 of the initial mechanism.
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