GB556160A - Improvement in sewing machines - Google Patents

Abstract

556,160. Sewing-machines. JACKSON, L. MELLERSH- (International Button Hole Sewing Machine Co.). March 18,1942, No. 3615. [Class 112] In a buttonhole sewing-machine, the divided workclamp is held in the spread position by the means used to close the clamp. The clamp arms 39, Fig. 2, are pivoted with axial freedom for the spreading movement on brackets 41 and press upon a pair of work plates 37, mounted for lateral separation and kept in parallel relationship by pairs of levers 48, 49. Their non-spread positions are determined by an adjustable wedge 57 and they are moved outwardly for spreading the work by the engagement of bowls 67 with a fixed wedge 66. The clamps are closed by means of cam-actuated lever 82 mounted on a stationary pivot 81 and carrying inwardlyextending lateral portions which engage over rearwardly-extending forked ends 84, Figs. 4 and 5, of the clamp arms. The engaging surfaces of the forked ends 84 and the parts of the levers 82 are inclined upwardly and outwardly so that the downward pressure of the levers 82 when the clamp is closed, whilst permitting the positive outward spreading movements, prevents any return movement of the clamp parts. In an alternative construction, the pivot pins of the clamp arms may be inclined instead of the surafces of the forked ends 84. The levers 82 are actuated to close the clamp by the straightening of a toggle mechanism. Specifications 285,710, [Class 112], and 435,922 are referred to.