Gears 1 and 2 rotate about fixed axes A and B. Driving gear 1 has one tooth a. When gear 1 rotates continuously, gear 2 rotates only during the periods that tooth a 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. To prevent unintentional rotation of gear 2 and to lock it during its dwell periods, tooth b of pawl 3, which turns about fixed axis D, enters a tooth space of gear 2. Pin c on gear 1 pushes pawl 3 out of engagement as tooth a engages gear 2. An impact occurs at the instant teeth a and d come into engagement.
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