Patent GB-285487-A (GB)
Title: Improvements in or relating to sewing machines
IPC: D05B57/14
Filed: 1928-02-15
Abstract: 285,487. United Shoe Machinery Corporation, (Assignees of Leveque, B. T.). Feb. 18, 1927, [Convention date]. Boot-sole sewing-machines. - In a lock-stitch hook needle machine, the shuttle is disconnected from the driving means before other parts of the machine are stopped. The needle-bar and feed mechanism may also be similarly disconnected. The machine is constructed on lines similar to those of the chain stitch machine described in Specification 228,489; the general arrangement, the power drive, the method of stopping including the disengagement of the needle-bar and feed mechanisms from the machine shaft, the feed and the presser mechanisms are substantially the same. Look stitching by shuttles.-The needle-bar 108, Fig. 2, is coupled by a link 112 to a lever 114 mounted on a fixed pivot 116 and connected to a parallel cam-actuated lever 118 by a latch 126 as in the previous case. An arm 190 of the lever 114 is linked to a lever 186, Figs. 2 and 19, carrying a toothed quadrant by which the shaft of the shuttle driver is oscillated. The barb of the needle is closed during the first part of its downward movement so as to retain the loop in the barb by a guard 192, carried by an arm 194 pivoted at 196 and oscillated by a pin 198 on the needle-bar which slides in a curved slot 200 on the arm. The needle thread take-up lever 216, Fig. 11, is mounted below the horn on a bracket 220 and is actuated by a crank-pin 202, link 206 and toggle-levers 210, 212. The lever 210 is mounted on the bracket 220 and the latter is adjustable about a centre 222 so as to vary the throw of the take-up. The thread passes to the thread roller of the take-up by way of an eye 230 in an auxiliary take-up 228 pivoted on the main take-up lever and controlled by a spring 232. The thread lock is provided by two discs one of which is fast on a spindle 238 and is urged towards the other by a spring. Two parts coaxial with the spindles of which one is fixed on the spindle have complementary wedge portions and, when the spindle is turned by means of an adge cam 204 and a lever arm 242, the wedge portions cause the spindle 238 to move axially and separate the thread-clamping discs. The shuttle is mounted in a detachable race 168, Fig. 9, and has a removable beak 174. The thread passes through the side of the bobbin case, under a tension plate 260 on the inner wall of the shuttle and back to a fixed eye 272 coaxial with the shuttle. Feed by device engaging the upper surface of the works. - A feed point 130 is secured in a carrier 132 hinged to a feed bar 134 and pulled on to the work by a spring so that it trails on the return movement. The feed bar has a slot mainly straight but with a downwardly turned front portion and is supported by two pins 138 on the presser-bar which are embraced by the slot. The curved slot and the pin produce the proper feeding movement out of a reciprocating movement imparted by a link 148 and a lever 146. The lever 146 is linked to a lever 142 having a cam slot in which rides a bowl 152 on the end of the needle-bar dividing lever 114. The lever 142 is normally spring-urged to the right and thereby receives an oscillatory movement which is transmitted to the feed point carrier. Presser-bars with periodic control.-As described in Specification 228,489, the presser-bar is urged towards the work by a spring 58 and a spring acting on a lever 66. It is lifted periodically by means of a curved lever 74, the angular position of which is determined, in accordance with the thickness of the work, by means of a pin 94 on the presser-bar and a lever 88 the upper end of which bears upon a rod 98. Stopping-gear; disengaging needle driving mechanism. - As described in Specification 228,489, when the main drive is disconnected and before the sewing shaft comes to rest, the lever 114 is disconnected at the top of its stitch by a movement of the lever 142 to the left. Thereby the needle-bar, the shuttle and the feed mchanism are disconnected from the sewing shaft. At the same time, the presser-bar is lifted and the needlethread lock opened by the following devices:- Two arms 282, 294 having steps 286, 296 at their lower ends hang respectively upon an eccentric 284 on a shaft 46 and on the shaft 46 itself. Thev are normally held to the right of the position shown by an arm 298 on a shaft 156. When the main clutch is opened, the shaft 156 is turned and the arm 198 is withdrawn. Thereupon springs 302, 304 urge the arms 282, 294 to the left and the arm 282 being constantly reciprocated by the eccentric 284 engages a lever 290 and raises it until the step 296 on the arm 294 passes under the lever and retains it in the position shown. The arm 290 is fast on the presser-lifting shaft 62 and a rod 254 operates a lever which engages an arm 258, Fig. 11, and turns the spindle of the thread lock.