Sewing machine with a stitch setting device

摘要

A sewing machine includes a material engaging part such as a dog which is engageable with a material workpiece to selectively feed it in a forward and a reverse direction. In addition, the sewing machine includes the usual mechanism for raising and lowering the dog so as to complete an advancing or reverse movement of the material. The dog is driven preferably by a mechanism which includes an eccentric which may be adjusted so as to vary the length of horizontal feeding movement of the dog while the elevational changes of the dog remain constant by a separate feeding control mechanism. The magnitude of movement of the dog is controlled in accordance with a stitch length to be sewed by a stitch setting device which includes a movable contacting member which is connected to the eccentric mechanism and is movable between two end positions in order to adjust by a selected amount the movement of the eccentric in driving the dog by a selected amount. The device also includes first and second setting members arranged on respective sides of a contacting member which may, for example, be in the form of a fluid operated piston and a setting member positioning means is connected to the two setting members so as to move them simultaneously in respective opposite directions and position them on respective opposite sides of the contacting member or piston so as to control the end positions of movement of the piston during the operation of the sewing machine. The piston rides in a fluid cylinder and fluid pressure may be applied to respective sides thereof for shifting the position of the piston for the purposes of reversing the direction of feeding movement of the material being sewn.