The output centerpoint of a Cardan gear mechanism is connected via a ball and a pin slideable therethrough to a lever which in turn carries a looper. Because the major axis of the lever and the axis swept out by the output centerpoint are skewed the lever is reciprocated back and forth along its own major axis while being rotated therearound. This results in the looper being swept back and forth along part of a generally helical-like path.

A sewing machine has a bed housing having a needle penetrating hole at one end thereof, an arm housing rising from the other end of the bed housing and extending to the one end of the bed housing over the bed housing, a laterally-long needle bar arm rotatably held in the arm housing and having a needle at the front end thereof, and a drive unit for swinging the needle bar arm with respect to the bed housing accommodated in the bed housing. The arrangement of the laterally-long needle bar arm and the drive unit accommodated in the bed housing, can effectively reduce the overall height of the sewing machine. It further reduces the weight and cost of the sewing machine, since no conventional material, such as cast iron having a heavy weight is used and die cast aluminum associating with a higher cost, may be employed for producing the arm housing.

A thread control mechanism for an overedge sewing machine uses only the movable driven components of the needle, lower looper, and upper looper, in combination with stationary thread guides, for feeding and controlling the threads used by the machine to form a seam. The lower and upper looper threads, i.e., the threads which pass through the eye of the lower and upper loopers, respectively, are each engaged by movable thread guides carried on the looper carriers for both loopers so that the coordinated movement of the two loopers cooperate to control and feed both looper threads. A needle thread takeup cam mounted on and driven by the needle arm drive shaft cooperates with stationary thread guides to feed and control the needle thread.

A needle driving apparatus for a sewing machine for allowing oscillatory movement of a needle bar through the motion of a lever which oscillates up and down interlocking with a main shaft, wherein a rectangular slider is rotatably supported by a fork provided on the end of the oscillating lever. On the upper end of the needle bar is fixed a guide member having a guide groove which is orthogonal with the needle bar and slidably fitted to the fork of the oscillating lever, and the rectangular slider is fitted in the guide groove of the guide member.

A Cardan gear assembly having an output centerpoint means which moves along an elliptical path. A force transfer means connects the output centerpoint to a means operative to carry a work performing means. The major axis swept out by the means operative being skewed with respect to the major axis of the ellipse which is swept out by the output centerpoint. As a result, the work performing means will be swept along a curve which is of a portion of a helix as well as part elliptical. This curve takes the form of a partial helix wherein the outgoing path is different from the return path.