To provide a differential feed upper sewing machine in which the seams on an insole and an instep of a shoe can maintain the same stitch length in processing of seaming the insole to the instep because an adjustment mechanism can change the relative position between an adjustment transmission part and a swing arm, and further adjust the rotation speed of a feed wheel with respect to a press wheel.SOLUTION: A differential feed upper sewing machine includes a body, a feed mechanism, a press mechanism, an adjustment mechanism, and a control mechanism. The body includes a swing arm that may be driven by a main shaft, and the feed mechanism includes a feed wheel that may be driven by the swing arm. The press mechanism includes a press wheel that can independently rotate, and the adjustment mechanism includes an adjustment driving source and an adjustment transmitting part. Because the adjustment driving source can rotate according to plural rotation angles, the adjustment transmitting part travels with respect to the swing arm so as to adjust the rotation amount of the feed wheel. In addition, the control mechanism can control the rotation speeds of both of the press wheel and the feed wheel.SELECTED DRAWING: Figure 3
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