GB454758A - Differential feeding mechanism for sewing machines - Google Patents

Abstract

454,758. Sewing-machines. FAIRWEATHER, W. C., 65, Chancery Lane, London.- (Singer Manufacturing Co. ; Elizabeth, New Jersey, U.S.A.) Feb. 19, 1936, No. 5010. [Class 112] A differential feed mechanism has main and auxiliary feed dogs mounted independently on opposite sides of the main shaft so interconnected that the feed stroke of the auxiliary dog can be varied by a treadle control while the machine is running. The invention is shown as applied to the differential feed mechanism described in Specification 252,643, [Class 112]. The mounting and operation of the main feed-dog 13 is as described in the above Specification. The auxiliary feed-dog 25 is carried by an upstanding feed-bar 26 at the opposite side of the mainshaft 6 from the main feed-dog mechanism. The fulcrum 27 of the feed bar 26 is vertically below the dog 25. The auxiliary feed-dog 25 is given its feed-lift movements by an arm 28 carrying the fulcrum 27 and a shaft 29 rocked by an eccentric 33 on the main shaft 6. This eccentric is so formed that it imparts a feed lift identical with that imparted to the main feeddog 13 by the eccentric 22. The upstanding feed-bar 26 has an arcuate slot 34 freely entered by a stud 35 on the end of the link 36 which is pivoted at its other end to the main feed-rocker at 15, so as to impart feed advance movements to the auxiliary dog 25. The extent of these movements is determined by the position of the pin in the slot. The position of the pin 35 in the slot 34 is capable of alteration, for varying the differentiation of the feed during the running of the machine, by a treadle chain 43. On exerting a downward pull on the chain, a lever 41 is pulled to its dotted line position, Fig. 3, about its pivot 40 on a fixed bracket arm 39. The lever 41 carries a slotted block 42 embracing a roller stud 37 on the link 36, so that as the lever 41 is pulled down, the stud 37 is lowered to depress the link 36 about its pivot 15, so lowering the position of the stud 35 in the slot 34 and increasing the feed stroke of the auxiliary dog 25 relative to that of the main-dog 13, for fulling-in the work.