Wheels 1 and 2 rotate about fixed axes A and B. The outline of each wheel is composed of two identical and symmetric portions of a logarithmic spiral with the equation r=ae^(mϕ) where r=radius vector of the outline, a=minimum radius vector, m=cot(µ); µ=constant angle between tangent t-t to the curve and radius vector r. The outlines of the wheels are centrodes in their relative motion. Without taking the sign into account, the transmission ratio in each position of the mechanism is i₁₂=ω₁/ω₂=B͞P/A͞P where ω₁ and ω₂ are the angular velocities of wheels 1 and 2, and P is the point of contact of the outlines and always lies on line AB. The average transmission ratio in a full cycle of motion of the mechanism is i₁₂= 1. The transmission ratio varies once each cycle within the limits from i_min=1/(e^(mπ)) to i_max=e^(mπ). Teeth are to be provided on the outlines of wheels 1 and 2 to obtain the full cycle of positive motion.
$2290$SG,3L$