Patent GB-199740-A (GB)
Title: Improvements in sewing machines
IPC: D05B27/10
Filed: 1923-06-25
Abstract: 199,740. Willcox & Gibbs Sewing Machine Co., Ltd., (Assignees of Merritt, A. A.). June 23, 1922, [Convention date]. Sewing-machines; feed by wheels and dogs.-A feed-wheel especially adapted for use in machines dealing with work of greatly varying thickness is mounted on a carrier-bar movable relatively to the work, the wheel being driven from a shaft in the carrier which is continuously in gear with intermittently acting driving means on the frame. The wheel 160, mounted on a spring-pressed bar 165, has spiral gear-teeth meshing with those of a pinion 162 mounted on a shaft carried by the bar 165 and driven through an elongated pinion 170 and pinions 186, 183, 181, 179 from a worm 176 of special form fast on the needle-bar shaft 112. The threads of this worm have a pitch through half the circumference only, the remaining half being purely circumferential, so that the feed occurs during half of each revolution of the shaft 112. The pinions 186, 183, 181, 179 are mounted in a detachable bracket so that they can be readily replaced by gears of different ratio when it is desired to alter the length of feed stroke. The feed-wheel may be formed in two sections with a division between them as shown in Fig. 26, and a casing 211 enclosing the pinion 162 has tongues 215-217 which lie close to the feed-wheel and strip therefrom fragments of material which become detached from the work and tend to clog the teeth. An under feed-dog 95 cooperates with the feed-wheel, and is carried by a feed-bar 96 having a sliding-pivot mounting on a pin 97 and connected to a lever 98 which has a sliding-pivot mounting on an adjustable pin 99. The upper end of the lever 98 is pivotally connected to a two-armed member 102 which is given a turning and sliding movement on a fixed shaft 103 by a pitman 104 connected to a driving crank on the main shaft. The position of the pin 99 is adjusted by a rack meshing with a pinion rotatable by a hand-wheel 106 which closes an opening in the casing. The lower feed dog may be faced with material such as rubber. Presser - bar lifting devices; presser-feet. - Presser-bar lifting means are provided which comprise a lever 121, 117, the arm 121 engaging a lug on the presser-bar and the arm 117 being connected to a spring-returned needle-rod 118. A hand-lever 128 is connected to the lever-arm 117 by a slotted connecting-rod 131 the movement of which past a dead centre causes the lifting lever and presser-bar to be retained in the raised position. The presser-bar 140 carries spaced fingers 147, 148 terminating in part-cylindrical ends 149 which engage sockets 155 on a presser-foot and are held therein by set screws 156. The presser-foot comprises side members connected at their forward ends by rollers 153 and embracing at their rear ends the feed wheel. Multiple - needle, machines. - The machine broadly is of known type and comprises multiple needles 65 co-operating with thread-carrying loopers 66 mounted on a lever 68 sliding in a rotatable block 75a and actuated through a member 87, sliding and turning on a pin 88, a lever 86 and a pitman 88 driven from the main shaft. A spreader 72 co-operating with the loopers and pivoted in a supporting bracket 75 is actuated by a cam-groove in the lever 68 engaging a roller 73<1> on the spreader. A pivoted thread-guide plate 202, Fig. 18, is mounted in the work arm, threads being passed through holes 205 therein to avoid entanglement. The plate is held in position by spring action. Work-supports.-The work-plate comprises a U-shaped member 39 and a superposed slotted plate 45 positioned by pins and slots on the end of the work-arm and secured by screws.