Patent GB-508688-A (GB)
Title: Improvements in or relating to sewing machines
IPC: D05B15/04
Filed: 1938-01-04
Abstract: 508,688. Sewing-machines. BRITISH UNITED SHOE MACHINERY CO., Ltd., FRAMPTON, S. E., and ROBERTS, M. Jan. 4, 1938, No. 170. [Class 112] In a rotary shuttle for a hooked-needle lockstitch sewing-machine, the thread-case has its wearing parts formed separately so that they may be renewed when worn; some of these parts are also made reversible. In the form of which the periphery is shown developed in Fig. 5, the thread-case has a circumferential groove 23 and two intersecting circular counterbored apertures receiving reversible and renewable members 15, 25 which are prevented from rotation by engagement with one another, the inner and outer faces of these members being flush with the inner and outer surfaces of the threadcase and their outer faces being grooved to continue the groove 23. The thread passes from the bobbin through one of a pair of holes 17 in the member 15, along one side of the groove in the member 25, the corners of which are rounded off, and round a renewable pin 3. A resilient tension member 33, located in the groove 23 by a projection and notch 39, is engaged by a wedge 45 to press the thread against the member 25; the wedge 45 is located, and adjusted to vary the thread tension, by a series of teeth on it engaged by a tooth 41 on the member 33. When one hole 17 in the member 15 or one side of the member 25 becomes too worn the member may be reversed to double its life, and may then be renewed without changing the whole thread case. In a modification, Fig. 12, the thread-case has a rectangular aperture 87 to receive a reversible and renewable member 93 which completes the inner and outer surfaces of the thread-case, and the groove 23 and is provided with thread holes 17 and rounded corners 105 ; tension means similar to those shown in Fig. 5 are employed, pressing the thread against the side of the groove in the member 93. The thread passes from the member 93 through a hole 107 in a renewable member 109 sprung into a second groove 111 in the thread-case ; the hole 107 is placed near the inner surface of the member 109 to allow the maximum amount of wear towards the outside. A modified thread guide, Fig. 14, comprises a bent pin 113 fitted into holes 115 in the threadcase and held therein by a projection 119 on a member sprung into a groove similar to the groove 111. The boss of the shuttle case which bears on the pin of the shuttle is provided with a renewable bush. The threadcase is prevented from rotation by a projection on an arm 69, Fig. 1, which is mounted, and actuated to release the thread-case when required, as described in Specification 392,947. In order to facilitate manufacture, the shuttle is formed without the thread-guiding nose described in Specification 416,002, the arm 69 being provided with an extension 79 to take its place. Means for extracting the threadcase are provided, comprising an arm 65 pivoted on the arm 69 and spring-pressed to engage an undercut projection 63 on the thread-case under the control of a cam 71 in the actuating mechanism of the arm 69. Specifications 19020/10, [Class 112], and 410,463 also are referred to.