GB747535A - Latch mechanism for temporarily latching the machine head in a tilted position to the base of a sewing machine - Google Patents

Abstract

747,535. Stays for hinged articles hinges. SINGER MANUFACTURING CO. May 6, 1954 [May 11, 1953], No. 13208/54. Classes 65 (1) and 65 (2). Stays.-A sewing-machine head 1 hinged at 3 to a base 2 is held in a tilted position by means which will allow lowering of the head at a limited speed, but will lock if this speed is exceeded as, for example, in the event of the head falling freely. The holding means comprises a rack 11 pivoted to a bracket 12 beneath the head 1 and engageable by a pivoted pawl 35 formed so that its nose 36 is positively moved into a tooth space of the rack on movement of the rack, the pawl being biased in the opposite direction by means which will withdraw its nose from the rack before it comes into contact with a tooth if the speed of movement is below a predetermined maximum. In the arrangement shown, the rack is guided by a slot 16 engaging a fixed screw 20, and the pawl 35 is pivoted on a triangular plate 25 loosely mounted on the screw 20 and carrying a screw 29 projecting through the slot 16 so that the plate 25 keeps the pivot of the pawl in constant relation to the rack. The pawl has a tooth 37 so placed in relation to the nose 36 that one or other of these parts is always in a tooth space of the rack, engagement of the tooth 37 with any tooth of the rack forcing the nose 36 into another tooth space, and a oounterweighted tail 38 of the pawl biases it to bring the nose 36 clear of the rack. In upward movement of the rack the pawl will be rocked positively and freely by engagement of rack teeth alternately with the nose 36 and tooth 37 ; in slow downward movement, there is time for the counterweight to swing the nose 36 clear of the rack, after it has been moved into a tooth space by contact of the rack with the tooth 37, so that lowering of the head 1 is not hindered, but if a given speed is exceeded the nose cannot swing clear before being engaged by a tooth of the rack so as to stop the movement. Hinges.-Each hinge 3 comprises an element 4 pivoted in the base 2 and a stud 5 removably secured by a set-screw in a bore in the base of the machine head 1.