GB1318350A - Needle positioning mechanism for a sewing machine - Google Patents

Abstract

1318350 Sewing machines SEWPRIMA Ltd 23 Oct 1970 [29 Oct 1969] 52949/69 Heading DIG In a sewing machine having a main shaft 1 driven at normal working speed by a main motor driving a pulley 2 coupled to a main drive wheel 4 through an overrunning pawl and ratchet clutch 6 and at a lower speed prior to stopping by a secondary motor 7 driving a second spindle 8 clutched to the wheel 4 through a second overrunnnig pawl and ratchet clutch 11 when the main drive ceases, means are provided to trip the clutch 11 and stop the machine in a predetermined position. The ratchet wheel 10 on shaft 8 drives through a friction disc 14 or. disc 12 loosely mounted on shaft 8 and carrying a pin 15 adapted to engage a stop pin 17, a second pin 16 being adapted to trip the pawl 11. During normal operation wheel 4 is rotating faster than wheel 10 and centrifugal force keeps pawl 11 out of engagement with the wheel 10. When the operator applies a brake to stop the machine, rotation of pulley 2 stops and wheel 4 slows down to a speed at which pawl 11 engages wheel 10 so that wheel 4 continues to be driven by motor 7. Wheel 10 also drives disc 12 until pin 15 engages stop 17 at which position pin 16 releases pawl 11 and the wheel 4 stops instantly in a predetermined position e.g. needle raised. A second pin 15a may be provided on disc 12 for stopping in a second position e.g. needle lowered, a solenoid 18 being operated to withdraw stop 17 momentarily to allow the pin 15 or 15a to clear it the disc 12 then rotating from the position determined by one of the pins to that determined by the other.