GB495364A - Improvements in or relating to button hole sewing machines - Google Patents

Abstract

495,364. Sewing-machines. DURKOPPWERKE AKT.-GES. March 25, 1938, No. 9152. Convention date, Sept. 2, 1937. [Class 112] In a buttonhole-sewing machine, means are provided whereby automatic opening of the work-clamp at the completion of a sewing operation may be prevented if desired. In the arrangement shown, the upper clamp members d are carried on pivoted arms k which are integral with hook-shaped arms f engaging lugs g on a yoke h pivoted to the work-plate c at i. The yoke h carries a crank n, o pivoted to it at p, and a hand-lever q is pivoted to the work-plate c at r and to the crank arm o ; a spring m is attached to the lower arm of the yoke h. By movement of the lever q to the right, the yoke h is forced downwards to pull the clamp arms k down, and the toggle linkage q, o is straightened to hold the clamp closed. As the work-plate completes its travel in the formation of a buttonhole, a lug s on the crank arm o engages the end of a lever t, pivoted at u on the frame and raised by a spring v, to break the toggle and release the clamp; this action may be prevented by depressing the lever t clear of the lug s by means of a hand plunger w. The clamp may be automatically closed by mechanism depressing the lever t to engage the crank arm n and press it down.