Pulleys 3 and 4 rotate about fixed axes A-A and B-B which intersect at an arbitrary angle. Guide pulleys 1 and 2 rotate freely on fixed axle 6 about common fixed axis C-C. Belt 5 runs over pulleys 3, 4, 1 and 2, contacting the pulleys with both of its sides. The transmission ratio from pulley 3 to pulley 4 is i₃₄=ω₃/ω₄=n₃/n₄=-(R₄/R₃) where ω₃, ω₄, n₃ and n₄ are the angular velocities and speeds (in rpm) of pulleys 3 and 4, and R₃ and R₄ are the radii of pulleys 3 and 4. Looking along axes A-A, B-B and C-C in the direction of the arrows, pulleys 1 and 2, and pulleys 3 and 4 rotate in opposite directions.
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