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SIX-SLOT GENEVA WHEEL MECHANISM WITH A LOCKING LEVER

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Driver 1 rotates about fixed axis A and carries pin a which consecutively engages straight radial slots d of Geneva wheel 2. Geneva wheel 2 rotates about fixed axis B and its slots are located symmetrically at angles of 60° between the axes of adjacent slots. Driver 1 is rigidly attached to cam b which actuates roller c, periodically turning two-arm lever 4 about fixed axis D. At this, roller e enters a slot d of Geneva wheel 2 to prevent its unintentional rotation during its idle periods. Lever 4 is held with its roller c contacting cam b by spring 3. When driver 1 rotates continuously at uniform velocity, Geneva wheel 2 rotates intermittently at nonuniform velocity with six rotation periods tᵣ and six idle periods tᵢ. The time of one revolution of driver 1 is T=tᵣ+tᵢ. The angles of rotation of driver 1 corresponding to an idle and to a rotation period of Geneva wheel 2 are ϕᵢ= 240° and ϕᵣ=120°. The angle of rotation of Geneva wheel 2 to each revolution of driver 1 is ϕ_G=60°. The rotation and idle factors are p=tᵣ/T=0.3333 and q=tᵢ/T=0.6667. The working time coefficient is k=p/q=0.5. The transmission ratio from the Geneva wheel to the driver is i₂₁=ω₂/ω₁=(λ(cos(ϕ₁)-λ))/(1-2λ cos(ϕ₁)+λ²) where λ=R/L, R is radius A͞C, L is centre-to-centre distance A͞B, ϕ₁ is the instantaneous angle of rotation of driver 1, and ω₁ and ω₂ are the angular velocities of driver 1 and Geneva wheel 2. Driver 1 and Geneva wheel 2 rotate in opposite directions. Owing to the symmetric profile on cam b, Geneva wheel 2 can rotate in either direction.
$2632$PG,GW$

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Documents: Gear mechanisms  [Streambook]
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