Patent GB-203359-A (GB)
Title: Safety device for sewing machines
IPC: D05B69/22
Filed: 1922-03-09
Abstract: 203,359. Fairweather, W., (Singer Manufacturing Co.). March 9, 1922. Button-hole sewing-machines; thread-cutters; starting and stopping gears; lock-stitching by shuttles.-In a sewing machine comprising a work-clamp, and needle-thread and under thread cutting-devices, a lock is provided to prevent manual actuation of the clamp-opening means and of the thread-cutters until after the machine has finally come to rest. The upper work-clamp lever 10 is pivoted at 11, Fig. 1, to a block on the longitudinal slide-plate. 12. The underthread cutter 18, Fig. 3, which coacts with the throat-plate on the opposite, side of the needlehole, is fixed to a laterally-sliding plate 15 which is actuated through a lever 28 by a stud 30 on arm 31. Fig. 1, of a bell-crank lever 31, 34 loosely mounted on a rock-shaft. 33. A thread pull-off 25, Fig. 3, pivoted to the frame at 21 is actuated bv a pin-and-slot connection with the plate 15. The lever 31, 34 is manually operated through a treadle-chain 35. From the end of the arm 34 depends a bar 67 the lower end of which is guided in an aperture in the base-plate 68. A lateral roll 72 of a block 71 slidably mounted on the bar 67 engages the rear end of the clamp-lever 10. The needle-thread cutting and nipping blade is mounted on a vertical shaft 37 on the clamp as described in Specification 4417/08. A crankarm 38 on the shaft 37 is pivoted to a rod 39 which is supported by an upstanding arm 40 of the clamp-lever 10. A spring connects the arm 40 and a collar 42 on the rod 39 on which is also mounted a stop-collar 41. An arm 44, Fig. 1, fixed to the shaft 33 carries a spring-pressed latch 45 which normally presses against the rod 39. An arm 51 fixed to the shaft 33 carries a spring-pressed pin 53 which contacts with a collar 57 fixed to the usual spring-pressed plungerrod 58 mounted in the stop-motion lever 61. Pivoted to the base-plate is a latch-lever 74, 76, one arm 74 of which engages under a collar 75 on the bar 67. Another arm 76 of the lever 5 slidingly engages the slotted end 78 of a rod 79 to which it is connected by a spring 80. The rod 79 is pivoted at its rear end to the stop-motion lever 61. Fig. 1. The bevelled end of the third arm 81 of the lever 5 engages the bevelled edge 83. Fig. 1. of a lever 84 pivoted to the base and actuated through a rod 88 of adjustable length from a lateral arm fixed to the shaft 33. When the stop motion lever is moved to dotted-line starting position shown in Fig. 1, the belt-fork 65 shifts the driving belt to the fast-pulley 63 the plunger-rod 58 is removed from engagement with the usual stop-motion cam 62 and the link 79 pulls the latch 74 under the collar 75. If the work-clamp is open, the collar 75 will prevent the starting movement of the lever 61. The rod 39 moves with the work-frame during its forward movement, so that its end passes the latch 45 which thereupon springs behind it. On the return feed-movement, the rod 39 is detained, while the shaft 37 moves rearwardly whereby the needle-thread cutting-blade is retracted, the spring between the arm 40 and the collar 42 being extended in readiness for the cutting stroke. When the lever 61 returns to stopping position, the link 79 moves forward without actuating the latch-lever, while the plunger-red 58 engages with the cam 62. Continued rotation of the cam depresses the rod 58, which exerts the usual braking action until it springs upward into the stop-notch of the cam. The movement of the lever 61 also brings the collar 57 into engagement with the pin 53 and on the subsequent descent of the rod 58, the pin 53 springs forward over the collar 57 to be lifted thereby when the rod 58 enters the stop-notch. The consequent rocking of the shaft 33 displaces the latch-lever 45 to allow the rod 39 to spring backwards for the cutting operation.' At the same time the link 88 is depressed so that, at the end of its movement, the lever 85 swings the latch-lever from under the collar 75, thus allowing the treadle to be depressed to open the clamp and actuate the under-thread cutting and pull-off mechanism. Specifications 18195/02, 17998/03, and 134,924 also are referred to.