GB673714A - Improvements in and relating to a sewing machine - Google Patents

Abstract

673,714. Sewing-machines. MEFINA SOC. ANON. Dec. 15, 1949 [Dec. 20, 1948], No. 32196/49. Class 112. Thread-tension devices; frames; controlling needle thread.-The tension device is placed inside the machine arm adjacent an opening for the passage of the thread, in a space separated from that enclosing the needle-driving mechanism; provision is made for easy adjustment. The device is preferably mounted on a cover closing the end of the arm. The tension may be released automatically when the presser-foot is raised. An auxiliary take-up, also adjustable, may be provided. In the form shown, the end portion 2 of the machine arm 1 is formed as a cover hinged at the lower edge at 6 and held closed by a catch 7 at the top ; it is slotted at 60 in its lower part to clear the thread. The usual tension discs 14, which may have a washer 16 between them to enable two threads to be used, are mounted on a hollow spindle 12 fixed in a plate 13 which separates the tension mechanism and the slot 60 from the mechanism in the arm 1, the discs being pressed together by a head 20 on a rod 31 which has a head 32 at the other end acted on by a leaf spring 30 adjustably fixed to a member 27 pivoted at 28 in lugs on the plate 13 and located by a blade spring 26 secured to it and bearing against an abutment plunger 24; adjustment of the tension is effected by means of a finger-wheel 17 with a cam face 23 which moves the plunger 24 inwards to increase the stress in the springs 26, 30. The tension is released when the presserfoot is raised by a finger 46 on a member 45 which is pivoted on an axis to the rear of the axis of the spindle 12 and has a cam tail engaged by the presser-lifting lever 43. Associated with the tension device is an auxiliary take-up comprising a spiral spring 34 extending forwards and outwards at its outer end 35 to provide a finger bearing downward on the thread, the downward movement of this finger being limited by a stop; the inner end of this spring is anchored in a member 37 frictionally mounted on the spindle 12 and adjustable thereon by means of a finger 38 projecting through the end face of the part 2.