GB505072A - Feeding mechanism for sewing machines - Google Patents

Abstract

505,072. Sewing machines. FAIRWEATHER, W. C. (Singer-Manufacturing Co.) Nov. 7, 1938, No. 32169. [Class 112] Feed.-In a sewing-machine having a feeddog 9 and puller feed-rolls 33, 35, the two feeds being separately adjustable, means are also provided for varying the two feeds simultaneously and equally without stopping the machine so that shorter stitches may be formed at certain parts of a seam. In the machine shown, the feed-dog 9 is mounted on a feed-bar 10 which derives its lifting movement from an eccentric 60 on the main lower shaft of the machine and its feeding movement from an arm 12 on a rockshaft 13 ; the lower feed-roll 33 is mounted on an actuating shaft 23, the upper roll 35 being freely mounted in a spring- pressed carrier 38 provided with a lifting lever 41 with a holding latch. The shaft 13 is driven from the shaft 8 by an adjustable eccentric 20, Fig. 4, actuating a pitman 19 with a pin 17 carrying a slide block which engages an arcuate slotted arm 14 on the shaft 13 ; the pin 17 has an eccentric portion, so that by rotary adjustment of it. the feed-dog 9 can be centred in its slot in the throat-plate. The shaft 23 is driven from the shaft 8 by a second adjustable eccentric 46, Fig. 5, synchronized with the eccentric 20, actuating a pitman 46 with a pin 56 engaging an arcuate slotted arm 47 fixed to the driving member of a ratchet clutch which drives the shaft 23 intermittently in one direction when the arm 47 is oscillated; backward movement of the shaft 23 is prevented by a second ratchet clutch having one member held stationary by a forked arm 54 engaging a stop block 55 on the machine frame. The mechanism for simultaneous variation of the two feeds comprises a forked arm 21, Fig. 4, freely mounted on the shaft 23 and embracing the pin 17, an arm 26 clamped on the hub of the arm 21, and a lever 28 pivoted to the frame at 29 and connected to the arm 26 by a link 27 ; the arm 28 has a portion 28<1> of channel section embracing the end of the pitman 46, Fig. 5, and slotted to receive the pin 56. Movement of the lever 28 by means of a treadle and chain 32 thus shifts the pins 17, 56 along the arms 14, 47 to vary simultaneously the amplitude of the feeding movement of the shafts 13, 23, the mechanism being so proportioned that equal variations are produced in the two feeds ; the mechanism is biassed to the long-stitch position by a spring. 30 attached to the arm 21.