GB800727A - Thread tension device for sewing machines - Google Patents

Abstract

800,727. Sewing machines. SINGER MANUFACTURING CO. Sept. 24, 1956 [Oct. 5, 1955], No. 29058/56. Class 112. Thread-tensioning devices. A thread tension device includes a tension release mechanism, particularly for operation by a presser foot lifter, and means for adjustment of the check spring. A rod 24, Fig. 1, secured against axial motion by a set screw 28, is journalled in the end wall 25 of a hollow boss 22 and has secured to its end a knob 35 and a plate 36 which abuts a guard plate 33 engaging the outer one of the tension discs 30 which are urged together by a slidable sleeve 44 having a flange 45 abutting a spring 46 held in compression by a nut 48 mounted on a threaded portion 47 of the rod. This nut is prevented from rotating by ears engaging longitudinal slots in a barrel 51, which is slidably mounted in a cylinder 53 and has a flange 52 overhanging the flange 45 and an arcuate extension 54 having an aperture 56 engaging an arm 57 of a lever 58 pivoted at 61. When the presser lifter lever 16 is raised it abuts the lever 58 and turns it in a clockwise direction against the action of spring 64 thus withdrawing the barrel 51 and, after a lost motion, sliding the sleeve 44 out of engagement with the tension discs. The check spring 67 has one end anchored to the cylinder 53, which is rotatably mounted in the boss 22 and locked therein by a screw 66, Fig. 5. Gear teeth 76 formed on the periphery of the cylinder opposite a slot 75 in the boss enable the cylinder to be rotated and the check spring tension to be adjusted.