Pulleys 3 and 4 rotate about fixed axes A and B which inter- sect at right angles. Quarter-turn belt 5 runs over pulleys 3 and 4, contacting the pulleys with one of its sides, and over identical coaxial guide pulleys 1 and 2 which rotate freely on fixed axle 6 about fixed axis C-C. 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 and B in the directions of the arrows, pulleys 3 and 4 rotate in the same direction.
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