GB765723A - Feeding mechanism for sewing machines - Google Patents

Abstract

765,723. Sewing machines. FAIRWEATHER, W. C. (Singer Manufacturing Co.). March 5, 1955, No. 6561/55. Class 112. In a differential drive for the main feed dog 26 and auxiliary feed dog 27 of a sewing machine, the main feed bar 28 and auxiliary feed bar 29 are slidably mounted at their forward ends on a block 37 which journals an eccentric 36 carried by a rotary drive shaft 42, whereby feed lift movement is imparted to the feed bars, the rear ends of the latter being slidably mounted on blocks pivoted on a fixed pin 34 ; a pitman 44 connects an eccentric 40, carried by shaft 42, to a pin 45 carried by the main feed bar, whereby feed advance movement is imparted to the latter; a link 61 connects pin 45 to a pin 59 carried by one arm 56 of a bell crank lever pivoted at 54 in the machine frame ; a slide block 63 is carried by the arcuate other arm 58 of the bell crank lever ; a link 65 connects a pin 64 carried by the slide block to a pin 73 carried by the auxiliary feed bar, whereby feed advance movement is imparted to the latter; and means are provided whereby the slide block may be moved along arm 58 during operation of the machine for varying the feed stroke of the auxiliary feed bar. A link 81 connects the pin 64 to a pin 83 carried by a crank 86, the latter being secured to a pin 89 which is journalled in the machine frame and also carries a toothed quadrant 90. A coil spring 96 biases pin 89 in the counterclockwise direction and thereby biases the slide block towards the base of arm 58. A pin 93, journalled in the machine frame, carries a toothed quadrant 91 engaged with quadrant 90, and also carries a crank 92, the free end of which is engaged with a chain 100 connected to a treadle, whereby crank 92 may be moved against the bias of spring 96 to shift the slide block towards the free end of arm 58, to lengthen the stroke of the auxiliary feed bar. Crank 92 passes between a pair of vertically adjustable bolts 105, 106 which limit the travel of said crank, and the frame adjacent the free end of the latter is provided with indicia markings 111 to indicate the amount of differential feed adjustment effected by the movements of crank 92.