Patent GB-926571-A (GB)
Title: Improvements in or relating to sewing machines
IPC: D05B57/00
Filed: 1960-02-01
Abstract: 926,571. Sewing-machines. GRITZNERKAYSER A.G. Feb. 1, 1960 [Feb. 2, 1959], No. 3408/60. Class 112. [Also in Group XXV] Frames; actuating rotary hooks.-The work supporting arm 9 of a sewing-machine is disposed parallel to, but rearwardly of, the machine arm, and its free end has a cranked part which extends forwardly to a position below the stitch forming mechanism depending from the machine arm. A cover 11 has a projection 12 which enters a recess 13 in the base 2 of the machine and is centred by a screw 14 extending into the arm. The bevel wheels 31, 32 driving the looptaker are enclosed by the cover and by walls 25, 26 and 29 in the arm, to protect them from sewing dust, and a flap 2 is hinged to the arm so that it may swing back from its closed position, where it is retained by a spring catch, to permit access to the looptaker. A finger is provided beneath the cover to hold the looptaker bobbin case against rotation. Feed by dogs; reversing and regulating.-The feed bar 43 (see Fig. 6), receives its feed advance movement from an arm 42 on an oscillating shaft 24. The bar is urged by a spring 44 on to a roller 41 journalled in the end of one arm 40 of a bell-crank lever, the other arm being engaged by a cam 36 on the looptaker driving-shaft 23 to oscillate the lever and provide feed lift movement for the feed bar. The direction and amplitude of the feed advance movement derived from the oscillation of the feed advance shaft 24 is determined by the arrangement shown in Fig. 9. A strap 47 embracing an eccentric 46 on the shaft 23 is pivoted at 48 to two links 49 and 50. Link 49 is pivoted to an arm 51 on the shaft 24 and the link 50 is connected at 52 to one end of a first order lever 54 rotatable about a pivot 53. The direction and amplitude of the oscillation of shaft 24 is determined by the position of the point 52 which is itself determined by the angular position of the lever 54. The other end of lever 54 is connected by a link 55 to one end of an actuating lever 56, the other end 58 of which is urged, by the action of a spring 57, on to a thrust bolt 59 which is slidably mounted in bores 60, 61 in an angle member secured to the column 3. A pin 64 on the bolt engages a recess 66 (see Fig. 11) in an adjusting disc 67 provided with a scale 72 and extending through a slot 71 in the column so as to be rotatable by the operator. The bolt 59 is urged outwardly by the lever 56 so that the pin is in contact with that boundary wall of the recess nearer to the centre, and the position of the disc, and hence the position of the point 52, and hence the amplitude of the feed advance motion, varies according to the angular setting of the disc. The direction of the feed is reversed by manually pressing the bolt inwardly when the pin 64 moves to contact the outside boundary wall of the recess and produce a reverse stitch which is always equal to that forward stitch which has been set by the position of the disc. Work supports.-To permit the feed dog to be rendered operative or inoperative the throat plate 75 is made L-shaped and symmetrical about an axis 76 (see Fig. 2) at 45 degrees to the work arm so that it may be turned over to bring either the slots 81 or the arched cover 79 over the feed dog and under the needle bar. To secure the throat plate in position it is provided (see Fig. 8) with a loose bolt 87 having heads 88 the lower one of which is pressed down to engage with a spring clip 84 secured beneath the cover 11.