Patent GB-142499-A (GB)
Title: Tension controlling mechanism for sewing machines
IPC: D05B49/04
Filed: 1920-04-30
Abstract: 142,499. Singer Manufacturing Co., (Assignees of Allen, E. B.). Feb. 16, 1918, [Convention date]. Button-hole sewing-machines. - An independently-driven single-revolution auxiliary shaft is used to cause, after the completion of the stitching, the release of the needle-thread tension, the cutting and nipping of the thread, the opening of the work-clamp, and the completion in one sweep of the revolution of the feed-wheel. The cycle of operations is initiated by the manual tripping into action of the usual single-revolution button-holecutting shaft 38. Towards the end of its single revolution, this shaft by means of a cam depresses an arm 51. The action of the stop-lever 45 being thereby removed, the stitching commences and continues until a pin 54 on the feed-wheel forces laterally a lever 55, which removes a detaining latch 49 from the stop-gear and permits the stoplever to become operative again. The movements of the stop-gear close the single-revolution clutch of a shaft 63. A crank 93 on this shaft is used to move the feed-wheel in one sweep through the remainder of a revolution and into its initial position. Bv means of a cam 106 on the shaft 63, the other actions incidental to the completion of the cycle are effected. A plate 107 is pivoted to a thread-tension releasing lever 108, is slidingly pivoted to the hand-stopping lever 116. and is supported at its end 119 on the periphery of the cam 106. At the commencement of a cycle, the end 119 rests as shown in Fig. 11, and the inward movement of the upper end of the stop-lever 45 pushes the end over the edge 141, thereby reinstating the thread tension at the commencement of stitching. In the revolution of the shaft 63, the cam portions 135, 136, 138 successively raise the plate 107 and thereby effect the release of the thread tension, the tripping of the thread-cutter, and the tripping of the work-clamp-opening device. The clutch operating the shaft 63 comprise a continuously rotating wheel 67, Fig. 9, having six inwardly projecting teeth 68 and a driven disk 72 having a sliding block, Figs. 5 and 8, spring- pressed outwards to engage with the teeth 68. The block 74 is normally held away from the teeth 68 by means of a stop-block 81 carried by a lever 80 and is released when the lever is moved anticlockwise from the position shown in Fig. 8. In the stopping of the main shaft, the usual stopblock 57, Fig. 8, rides up on the cam 58, the further end of the lever 96 is depressed, and a latch 98 slips under an arm 87 of the lever 80. When the block 57 drops into the positive stopping notch 61, the latch 98 rises with the lever 96 and the lever 80 is turned away from the disk 67. The block 74 is thereby released, moves outwards into engagement with one of the teeth 68, and the shaft commences its revolution. In the course of the revolution, one web of the crank 93 hits a plate 104 on a trip lever 100, removes the latch 98, and permits the lever 80 to move into position in readiness to engage the block 74 at the completion of its first revolution, an to withdraw it from engagement with the teeth 68.