Gears 1 and 2 rotate about fixed axes A and B. Gear 1 has one tooth c. When driving gear 1 rotates continuously, driven gear 2 rotates only during the periods that tooth c engages a tooth d of gear 2. To each revolution of gear 1, gear 2 turns through an angle equal to ϕ=2π/z₂ where z₂ is the number of teeth of gear 2. For the given mechanism, ϕ=π/3. To prevent unintentional rotation of gear 2 and to lock it during its dwell periods, gear 1 has concentric locking surface b which engages concave surfaces a on gear 2. When gear 1 rotates at uniform velocity, gear 2 has intermittent rotation. An impact occurs at the instant that teeth a and c come into engagement.
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