| 摘要 |
1,113,800. Sewing machines. FRATELLI BORLETTI S.p.A. 25 Nov., 1965 [27 Nov., 1964], No. 50201/65. Heading D1G. In a sewing machine, a cam on the arm shaft is adapted to impart oscillatory movement to a lever, whereby a guide carried by the lever exerts on the thread a pull so timed as to prevent the formation of a stitch, and oscillation of the lever is cyclically interrupted to allow stitch formation after a number of cycles of movement of the needle. As shown, the upper arm shaft 1 carries a cam 2 co-operating with a follower 5 rigid with a sleeve 6 journalled on a fixed pin 7 and biased by a spring 4 against cam 2. A lever 9, rigid with sleeve 6, carries a needle thread guide 10 which moves, at needle penetration, from a position b to a position a for exerting a pull on the needle thread to prevent the formation of the thread loop normally seized by the looptaker beak. A cam 16 on shaft 1 cooperates with a follower to oscillate a pawl 17 for driving a ratchet wheel 18 step by step. A lug 14 on wheel 18 is adapted, at each revolution of wheel 18, to engage a lug on sleeve 6 for preventing movement of guide 10 to position a and thereby allowing the formation of a stitch, A lever 19, pivoted on pin 7, is formed with lugs 20 and 21 adapted, when lever 19 is in the full line position C, to engage arm 9 and a lug 22 on pawl 17 respectively, for preventing oscillation of arm 9 and rotation of wheel 18, and thereby allowing normal stitch formation. |
