The single needle lockstitch zig-zag machine is used for straight stitch, 1-step, 2-step and 3- step zig-zag operations in the production of sails, tents and tarpaulins as well as for leather processing. The machine equipped with bottom feed and top puller feed for very heavy-weight materials, large barrel shuttle hook system, electropneumatic backtacking with sewing foot lift and 760 mm clearance always ensures a safe seam, even with heavy-weight materials.