Abstract: A sewing mechanism is equipped with a drag clamp assembly for holding the ends of the fabric plies. The drag clamp assembly comprises two laterally spaced-apart clamps which are movable relative to each other in the sewing direction and of which the first clamp is opened when it is adjacent a contour control device, and the second clamp laterally thereof is opened near the stitch forming area. The drag clamp assembly enables the contour control device to remain in a working position during the entire sewing operation, and the clamp moving past the contour control device holds the fabric plies taut up to the end of the sewing operation.