Link 2 is connected by turning pairs A and B to sliders 1 and 3 which move along fixed guides b-b and d-d. When slider 1 moves along guides b-b, point C of link 2, at the point of intersection of the axes of guides b-b and d-d, describes straight line a-a. Line a-a is perpendicular to axis 0x which makes equal angles with the axes of guides b-b and d-d.
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