The lengths of the links comply with the conditions: A͞B=B͞C=m and E͞B=B͞F=F͞D=D͞E=n. Figure EBFD is a rhombus linkage. Links 3 and 4 are connected by turning pairs A and C to sliders 1 and 5 which move along fixed guides p-p. When point B is moved along a curve with the equation F(x,u)=0, point D describes curve P(ξ,η)=0. Coordinates x, y, ξ and η are related by the conditions: x=ξ and y=kη where k=(m-2n)/m=const. Curve P(ξ,η)=0, described by point D, is a projection of curve F(x,y)=0 on a plane making an angle φ with the plane of the drawing and where cos(φ)=k.
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