Pulleys 1 and 2 rotate about fixed axes A and B which cross at right angles. Quarter-turn belt 3 runs over pulleys 1 and 2, contacting the pulleys with one of its sides. 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 axes A and B in the direction of the arrows, pulleys 1 and 2 both rotate clockwise.
$3506$SFL,BD$