GB953832A - Improvements in or relating to sewing machines - Google Patents

Abstract

953,832. Clutches; controlling clutches &c. DE 'JONG & DE VLIEGER MACHINEHANDEL N.V. Nov. 20, 1962 [Nov. 20, 1961], No. 43929/62. Headings F2C and F2L. [Also in Division D1J A clutch is provided for coupling or uncoupling the main spindle of a sewing machine and a pulley driven by a motor which is automatically braked on being switched-off, and the arrangement is such that the pulley and spindle are coupled during the starting and normal running of the motor, but are uncoupled after the motor is switched-off and are again coupled, in a particular angular position of said spindle, when the motor is substantially stationary, in order to stop the spindle in said position. The main spindle 2 of a sewing machine 1 has fixed thereto by screws 6 a sleeve 3 having radial ribs 7 fitting loosely in recesses formed in a cylindrical non-conducting member 9 which is journalled on sleeve 3. A pulley 17, coupled to the driving motor which is automatically braked on being switched-off, is rotatable and axially slidable in sleeve 3, and carries a magnetic disc 15 which is clutched to member 9, for driving spindle 2, on energization of a magnetic coil 14 mounted on member 9. The periphery of the latter is provided with three conducting slip rings 20, 21, 22 and a short conducting segment 23 which co-operate with brushes carried by a fixed arm 24. The brushes co-operating with rings 20 and 21 are connected to a rectifier 26, and the brushes cooperating with ring 22 and segment 23 are interconnected. Member 9 also carries a centrifugal switch 11, the moving contact of which shifts at a speed of 100-200 r.p.m., and a micro-switch 12 which is closed when member 9 commences to rotate and over-runs spindle 2. When the driving motor is switched-on, coil coil 14 is energized via ring 22, segment 23 and the contact 32 of switch 11. Immediately member 9 starts to rotate, switch 12 closes to establish a permanent circuit through coil 14. A second circuit is established through contact 37 of switch 11 when the motor speed increases. When the motor is switched-off, switch 12 opens first, and switch 11 disconnects coil 14 to uncouple spindle 2 when the motor slows down. Coil 14 is again energized via the contacts 22, 23 and the motor then being stationary and braked, spindle 2 is also halted. Contact 23 may be positioned to stop the machine with the needle either fully raised or fully lowered. A second contact may be provided, aligned with contact 23 and connected in parallel therewith by a two-way switch, for stopping the machine in alternative positions.