Lockstitch sewing machine

A lockstitch sewing machine comprising a worktable and a presser foot arranged at an operating locality of the machine for clamping a workpiece therebetween and for feeding such workpiece step-by-step through the operating locality;

• a mounting for a curved hooked needle and a further mounting for a curved awl arranged in a common vertical plane and at opposite sides of the worktable, at the operating locality of the machine, and mounted for pivotal movement about a common axis,
• means for looping thread over the needle hook, after the latter has penetrated a workpiece being stitched and while it is projecting therethrough, retraction of the needle then causing the loop of thread to be drawn through the workpiece,
• means, including a rotatable shuttle, by which a lockstitch can be formed with said thread and a further thread, and
• means for thereafter drawing the lockstitch thus formed into the body of the workpiece, wherein the needle mounting and the awl mounting are caused to pivot each by a crank mechanism,
• and further wherein the mechanisms are mounted on a common crank shaft and each is operatively connected to its associated mounting through a bell crank lever arrangement, said arrangements being mounted on a common pivot arranged intermediate the crank shaft and the common axis of the mountings for the needle and awl.