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Tension selecting mechanism for sewing machines

  • US 4,180,006 A
  • Filed: 03/31/1978
  • Issued: 12/25/1979
  • Est. Priority Date: 03/31/1978
  • Status: Expired due to Term
First Claim
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1. An improved tension selecting mechanism for a sewing machine having a frame including a work supporting bed and a hollow upwardly open bracket arm overhanging said bed, an arm top cover to enclose said open bracket arm having a horizontal slot formed therein, an endwise reciprocating thread-carrying needle, a needle thread tension device including a first thread engaging disc and a second thread engaging disc carried on a supporting stud for applying frictional resistance to the movement of a needle thread between said first and said second discs, an axially shiftable rod for moving said first thread engaging disc toward and away from said second thread engaging disc, a lever having a supporting fulcrum and a free end, means on said lever spaced from said fulcrum for engaging said axially shiftable rod, leaf spring supported relatively to said sewing machine frame and having a contact point formed at one end thereof to impart a spring bias to a location along said lever between said free end and said fulcrum to apply a tension to said axially shiftable rod, wherein the improvement comprises an operator influenced clamp means for adjusting the point of contact between said lever and said leaf spring, said clamp means including a stud projecting from said leaf spring through said slot in said arm top cover, said stud being substantially perpendicular to the axis of said lever, means associated with said stud for frictionally resisting movement thereof along said slot, and a selecting knob on said stud slidably carried exteriorly of said arm top cover for slidably varying the point of contact between said lever and said leaf spring.

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