Pulleys I and 2 rotate about fixed axes A and B which cross at right angles. Belt 5 runs over pulleys 1 and 2, contacting the pulleys with both of its sides, and over two identical guide pulleys 3 and 4 which rotate about parallel fixed axes D and C. The transmission ratio from pulley 1 to pulley 2 is i₁₂=ω₁/ω₂=n₁/n₂=R₂/R₁ where ω₁, ω₂, n₁ and n₂ are the angular velocities and speeds (in rpm) of pulleys 1 and 2, and R₁ and R₂ are the radii of pulleys 1 and 2. Looking along axis A in the direction of the arrow, pulleys 1 and 2 both rotate clockwise.
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