Circular eccentric 1, rotating about fixed axis A, is connected by turning pair B to link 3. Link 4 has collar d encircling eccentric 1. Link 5, turning about fixed axis D, is connected by turning pairs E and F to links 3 and 6. Links 4 and 6 are connected by turning pair G. Eccentric 1 is rigidly secured to link 2 which has slot b along which pivot B can be adjusted and clamped. This changes length A͞B. When eccentric 1 rotates, teeth a describe connecting-rod curve x when A͞B=A͞C, curve x₁ when A͞B>A͞C and curve x₂ when A͞B=0. In the last case the stitch length equals zero.
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