Drive pulley 1 consists of two rigidly attached (or integral) steps a and b of radii r_a and r_b. This pulley is the carrier of a planetary mechanism and is connected by a turning pair to planet gears 2 and 4 which are rigidly attached together. Planet gear 2 meshes with fixed sun gear 3; planet gear 4 meshes with gear 5 which, together with driven gear 6, are keyed to shaft d. The speeds n₁ and n₆ of pulley 1 and gear 6 (in rpm) are related by the equation n₆=-n₁(z₃z₄-z₂z₅)/(z₂z₅) where z₂, z₃, z₄ and z₅ are the numbers of teeth of gears 2, 3, 4 and 5. Pulley 1 and gear 6 rotate in opposite directions. The driving belt can be shifted to either step a or b of the pulley, obtaining angular velocities of ω_a or ω_b for gear 6 which are related by the condition ω_a/ω_b=r_b/r_a.
$2881$CxG,PR$