Patent GB-705829-A (GB)
Title: Feeding mechanisms for sewing machines
IPC: D05B27/02
Filed: 1952-11-04
Abstract: 705,829. Sewing-machines. SINGER MANUFACTURING CO. Nov. 4, 1952 [Nov. .14, 1951], No. 27722/52. Class 112 Feeding. Differential feed mechanism comprises a pair of feed bars or carriers 42, 43 for main and auxiliary feed dogs 40, 41 respectively, an eccentric 50 mounted on a rotary shaft 36 and embraced by each feed bar for imparting oscillatory movement thereto, an eccentric 54 mounted on the shaft 36 and connected by a first pitman 56 to the feed bar 42 for imparting reciprocating movement thereto, a rocker 61 adapted to impart t reciprocating movement to the feed bar 43, a second pitman 59 embracing at one end an eccentric 58 on the shaft 36 and pivotally and slidably connected at its other end to the rocker, and means comprising an operatorcontrollable lever 82 coupled to the second pitman for sliding the point of connection between the latter and the rocker to vary the degree of reciprocating movement imparted to the feed bar 43. The feed bars are slotted at both ends, the front slots slidably engaging a block 51 which journals the eccentric 50 and the respective rear ends slidably engaging blocks 46, 47 mounted on a pin 48 press-fitted into a bushing 49 secured to the frame 15 of the machine. The pitman 56 is journalled on the eccentric 54 and is pivoted on a post 57 field to the feed bar 42. The feed stroke of the main dog 40 may be varied by substituting eccentrics of the desired eccentricity for the eccentric 54. The pitman 59 is journalled on the eccentric 58 and is pivoted on a pin 71 carried by a U-shaped strap 70 which slidably embraces a curved arm 60 of the rocker. The latter is pivoted at 61<1> on the frame and comprises a second arm 66 connected by a link 68 to the feed bar 43. The strap 70 carries a second pin 72 disposed in a curved slot 85 formed in one arm 84 of the lever 82, the latter being pivoted on the frame and comprising a second arm 86. The arms are connected together by a screw 87 and a pair of sleeves 88, 89, the latter of which is journalled in the frame. The arm 86 is connected by a chain 92 to a treadle and carries a pin 93 engaged in the slotted end 94 of one arm 102 of a bell-crank lever pivoted at 96 on the frame. A spring 97, coiled about the pivot 96 and having one end secured at 101 to the arm 102 and the other end secured at 99 to the frame, is adapted to raise the arm 86, and hence the member 70, to a position in which the feed strokes of the main and auxiliary dogs are equal. Member 70 may be drawn downwardly through the chain and treadle to increase the feed stroke of the auxiliary dog. The other arm 104 of the bell-crank lever terminates in a finger 105 adapted to travel over the graduated edge of a plate 24 to indicate the degree of differential feeding. The plate 24 is formed with a series of screwthreaded holes adapted to receive a headed screw 107 which thereby functions as an adjustable stop for the arm 104. Presser bars. A presser foot 18 is carried by a presser bar 19 universally pivoted at 21 to the head 16 of the machine and is urged downwardly by a spring-biased member 20. A pin 30 carried by the presser bar overlies a crank 28 carried by a spindle 23 journalled in the machine head. The spindle also carries the aforesaid plate 24, the latter being connected by means of a chain to a treadle adapted to lower the plate 24 against a spring 32, and thereby raise the crank 28 and hence the presser bar and foot. A lever is provided for relieving the pressure of the spring-biased member 20.