GB897799A - Improvements in sewing-machines - Google Patents

Abstract

897,799. Sewing machines. CLINTON INDUSTRIES Inc. Sept. 1, 1960 [Oct. 5, 1959], No 30237/60. Class 112 [Also in Group XXIV] A sewing-machine comprises a reciprocable needle bar, a drive motor, a driven shaft connected to the said needle bar, a drive shaft connected to the motor, first and second oppositely acting unidirectional rotary coupling devices and means selectively disengaging one of the said coupling devices. The sewing machine main drive motor 17, which is started or braked respectively by the depression or release of the treadle 20 is connected by a belt 31 to a pulley 29 on a drive shaft 26 disposed within the bore of a tubular shaft 24 journalled in bearings 27. First and second clutch members 39, 47 are keyed to the shafts 26, 24 respectively and are coupled together by first and second springs 68, 70 which perform as oppositely acting unidirectional friction clutches (see Group XXIV). The coupling action of the spring 68 may be released by means including a solenoid 90. A sprocket wheel 59 mounted on a sleeve 58 rotatably carried on the shaft 24 is connected by a chain 63 to the needle positioning motor 65 and by a further unidirectionally acting spring 71 to the second clutch member 47. The shafts 24 and 26 are thus normally rigidly connected together in both directions so that the latter may drive the former, but upon disengagement of the spring 68 and the braking of the main drive motor 17 the shaft 24 may be rotated, in a forward direction only, through the sprocket wheel 59. As the shaft 24 rotates a cam 37 thereon operates in succession switches 100, 101 disposed in positions corresponding to the raised or lowered position of the needle. Straddling the sleeve 58 (see Fig. 6) is a saddle 91 which may rock slightly, between stops 96, 97, as the sprocket and sleeve rotate, and operate normally open switch 98. A switch 121 (see Fig. 8) is connected to the foot treadle and a further switch 123 is operable by a knee lever 127. When the machine is actuated for normal sewing operation foot treadle 20 is depressed and knee-lever 127 is released, the main motor 17 then driving the machine by way of pulley 29 shaft 26, clutch members 39, 47 and coupling spring 70, shaft 24 and pulley 32. When it is desired to stop the machine in the needle raised position the treadle is released, motor 17 is braked and stops the sewing machine through the shafts 26 and 24 by way of the spring 68. Raising the treadle closes switch 121 to energize solenoid 90 which disengages the spring 68 to permit the advance of shaft 24 relative to shaft 26, to energize relay 109 to cause arms 110, 111 to meet contacts 114, 115 to energize the positioning motor's armature 106 and field coils 107 in a forward drive sense and drive the sewing machine by way of sprocket 59, spring 71 and shaft 24 until as the needle bar reaches its raised position, cam 37 opens switch 100 to de-energize both the solenoid 90, to lock the shafts 24, 26 together and the needle in its raised position, and the relay 109. The arms 110 then move to the reverse position shown and the positioning motor moves in reverse, the spring 71 slipping, until the sleeve 58 and hence the saddle 91 has moved sufficiently to open the switch 98. To stop the machine at a needle lowered position the knee lever 127 is actuated to change over switch 123 and bring switch 101 into circuit in place of switch 100.