GB1425185A - Feeding mechanism in a sewing machine - Google Patents

Abstract

1425185 Sewing machines G TOLLE 23 Feb 1973 [20 March 1972] 8915/73 Heading D1G [Also in Division F2] In a buttonhole sewing machine having the needle bar under the work and the loop taker above it on a pivoting bracket arm, the work clamp 30 (described in Specification No. 8912/ 73) is attached to a threaded shaft 57 which is driven forward and back automatically by a pulley 54 on an internally threaded sleeve 51. The driving belt 70 is indexed either forward or back by a mechanism (Figures 7 and 8) driven by two eccentrics 74, 75 on the main drive shaft 20. When the work clamp reaches the end of its travel in either direction it trips an escapement mechanism which sets in train the reversing of the driving belt 70. A lug 186 on the work clamp depending between the arms 183 strikes one arm 183 and a stop lever 175 is tilted so as to release the feed reversing cam 140 and allow it to rotate through “ turn before engaging the stop lever 175 again. In rotating a lobe 160 on the cam 140 strikes a bell crank lever 136 (Fig. 9) and pushes out whichever end of its is inwards. This causes a link 130 (Figure 9) to partially rotate a sleeve 125 on a shaft 72 and the sleeve is connected by a toggle action (Fig. 5) to the feed frame 97 which reverses the belt indexing mechanism 73. In the indexing mechanism (Figures 7, 8) the angular position of the frame 97 will alter the movement of the bell crank lever 82 through toggle links 95, 95' and so alter the direction which the shoe 89 drives the belt. The feed reversing cam 140 is driven by the worm and wheel, the worm being driven from the main drive shaft 20 via a belt 25 and a friction clutch 201, 203. When the gear wheel is stopped by the stop lever 175 the worm will tend to ride along the gear wheel leftwards until the clutch faces separate. When the gear wheel 142 is next released a spring 205 presses the clutch faces into engagement again.