GB892077A - Improvements in or relating to sewing machines - Google Patents

Abstract

892,077. Sewing machines. NECCHI S.p.A. April 27, 1960 [May 11, 1959], No. 14727/60. Class 112 [Also in Group XXIV] The main shaft of a sewing machine is driven through a single revolution by means comprising a driving member journalled on the main shaft, a spring rigid at one end with the main shaft and coiled around said member to couple the latter frictionally to the main shaft, an abutment adapted to engage the other end of the spring for releasing the frictional coupling, and handoperated means adapted to move said abutment from a position engaging the spring end and to return the abutment to said position before said spring end has completed a single revolution with said member and shaft. The machine is arranged to stop with the needle in its uppermost position, and the machine is thereby enabled to form individual stitches. A pulley 8, journalled on the main shaft 3 and driven by a belt 7, is formed with a surface 9 on which is coiled a spring 10. One end of the latter is anchored by means of an eye 11 to a pin 12 carried by a block 12<SP>1</SP> rigid with the handwheel 13 fast on shaft 3. The other end 14 of the spring is anchored to a radial lug 15 on a ring 16 journalled on the central boss of the handwheel 13. Ring 16 is turned clockwise by spring 10, and the latter thereby grips the surface 9. An abutment 20 may be interposed in the path of movement of lug 15, whereby the latter is moved counterclockwise to engage a rubber pad 19<SP>1</SP> on block 12<SP>1</SP> and spring 10 is unwound to release its grip on surface 9. Abutment 20 is the free end of a lever 21 pivoted at 22 on the machine frame. A spring 24 biases lever 21 to engage an extension 23 on the latter with a cam 25 rotatable by means of a handle (not shown). When extension 23 engages a trough of cam 25, abutment 20 engages lug 15. A lever 30, pivoted at 33 on the machine frame, has pivoted thereto at 29 a lever 28 carrying a lug 31 biased against the edge of lever 30 by a spring 32 on pivot 29. A spring 36 biases lever 30 to engage a nose 37 on lever 30 with a fixed stop 38, when a nose 27 on lever 28 engages a bracket 26 on lever 21. When lever 30 is turned counter-clockwise by means of a handle 35, nose 27 co-operates with bracket 26 to swing lever 21 and thereby disengage abutment 20 from lug 15. Bracket 26 then rides over the upper edge of lever 28, whereby abutment 20 resumes its original position to engage abutment 15 after shaft 3 has turned through one revolution. If cam 25 is turned to engage a crest thereon with extension 23, abutment 20 and bracket 26 are moved permanently out of the paths of movement of lug 15 and nose 27.