The double-chainstitch machine 173 is the machine for rational sewing of smooth seams in difficult-to-feed material. This is guaranteed by the intermittent puller top feed. It operates absolutely synchronous to the bottom feed, even at a speed of up to 6000 stitches/min. The feeding speed of the puller top feed is differentiable to the bottom feed without any problems. So it is possible to sew displacement-free seams in every material. If required, the puller can be swivelled completely out of the sewing area so that the 173 can also be used without puller.