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Description
Five-tooth ratchet wheel 1 rotates freely on fixed axis A. Disk a with one tooth space is mounted on a common hub with ratchet wheel 1. Wheel 1 has recess c on its surface. Locking pawl 2 turns about fixed axis B. One end of flat spring 3 is attached to pawl 2 and the other end to knife 4. Knife 4 has a longitudinal slot which slides along pin b fixed in the frame. Attached to the knife is feeding pawl 5 with weight 8, holding pawl 5 from underneath against ratchet wheel 1. In the idle position, the tooth of pawl 2 is in the recess of wheel 1 and knife 4 is withdrawn. When link 6 is turned clockwise, the tooth of pawl 7 enters the tooth space of disk a. When link 6 turns back again, pawl 7 turns disk a together with ratchet wheel 1. At this, pawl 2 is forced out of the recess in wheel 1, turns clockwise about axis B, and its other end is retracted from spring 3. This allows knife 4 to advance and hook the thread. In its rapid retraction knife 4 cuts the thread. $1853$LR,FD$
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