Trunnion A of pinion 1 slides along fixed straight guide a. Gear 2 has complex slot b and rotates about fixed axis B. Slot b consists of two circular portions not extending around a complete circle and connected together at their ends by semicircular slots. Gear 2 has teeth c of the mangle type located in a circular arc within the portions of slot b. When pinion 1 rotates and axis A is in its lower position in guide a, pinion 1 meshes with gear 2 with external engagement (at the outside oteeth c) and gears 1 and 2 rotate in opposite directions. When axis A is in its upper position in guide a, pinion 1 meshes with gear 2 with internal engagement (at the inside of teeth c), and gears 1 and 2 rotate in the same direction. Thus gear 2 rotates alternately an incomplete revolution in each direction with dwells at the extreme positions. When pinion 1 meshes externally with teeth c (trunnion A slides along the outer portion of slot b), gear 2 rotates at the angular velocity ω₂=ω₁(r₁/r₂), and when it meshes internally with teeth c (trunnion A slides along the inner portion of slot b), gear 2 rotates at the angular velocity ω₂'=ω₁(r₁/r₂'), where r₁ is the pitch radius of pinion 1, r₂ and r₂' are the pitch radii of teeth c for external and internal engagement with pinion 1, and ω₁ is the angular velocity of pinion 1.
$2320$SG,3L$