GB839233A - Thread tension mechanism for sewing machines - Google Patents

Abstract

839,233. Sewing machines. SINGER MANUFACTURING CO. Sept. 13, 1957 [Sept. 14, 1956], No. 33198/58. Divided out of 839,231. Class 112. Thread controlling, thread-tensioning devices. In a sewing machine having a thread tensioner comprising a pair of spring-biased discs 46 mounted on a stud 44, a plate 73 is mounted for sliding movement along a line in a plane normal to the axis of said stud, and a shaft 20 journalled on an axis parallel to that of said stud carries a crank pin 77 normally disposed in a notch 79 provided at one end of a slot 80 formed in plate 73 concentrically with the axis of shaft 20, the arrangement being such that initial movement of shaft 20, effected by operator-influenced means, causes sliding movement of plate 73, whereby a pin 75 carried by the latter separates the discs 46 to release thread tension, further movement of shaft 20 serving to hold plate 73 in tension-releasing position without effecting further penetration between the discs by the releasing pin. Shaft 20 also operates the presser bar lifting means, the latter containing a lost-motion connection, whereby the thread tension is released before lifting of the presser bar' commences. As shown, a pair of thread tensioners 42, 43 is provided. The discs 46 are pressed against a collar 45 on stud 44 by a spring 47 which also abuts a flange 52 formed on a sleeve 49 provided with a finger 50 disposed in a slot 51 formed longitudinally in stud 44. A nut 48, screwed on the end of the latter, engages the serrated outer face of flange 52. The screwed inner ends 54 of the studs pass through a plate 58, the stud of tensioner 42 carrying a nut 65, and the stud of tensioner 43 screwing into a boss 66 on the standard 2 of the machine. Mounted on each portion 54 is a pair of thread guides 56, 57, guide 56 having a single arm formed with thread holes 60, and guide 57 having a pair of arms formed with respective thread holes 63, 64. Plate 73 is formed with slots 74 through which reduced portions 53 of the studs pass. A further stud 67 passes through another slot 74, a spacer 72 and plate 58, and screws into a boss 71 on the standard 2. Presser bars. Shaft 20, provided with a crank connected to a treadle or the like, is also connected by a linkage 25, 27, 30, 38, 39 ton an arm 16 fixed to the presser bar 5. The free end of arm 16 lies within a guide slot in a fixed plate 17. A spring 28 biases shaft 20 to the position corresponding to the lowered position of the presser bar. A pin 40 on arm 16 lies within a slot 41 in link 39 to provide a lostmotion connection enabling the presser foot 8 to follow inequalities in the work without affecting said linkage. The presser bar is biased downwardly by a compression spring 10 which abuts the lower end of a longitudinal bore 9 in the presser bar and a rod 11 which screws through the machine head 4 and enters the upper end of bore 9.