. A treading exercise machine with an elliptical trace comprising a base, a first pivotal shaft, a second pivotal shaft, a supporting rod, and a pair of treading rods; wherein
a front end of the base has the supporting rod; a middle section of the supporting rod is installed with the first pivotal shaft which passes through a though hole in the supporting rod and arranged at two sides of the supporting rod; a top of the supporting rod is installed with a control panel and a handle; a rear end of the base has a second pivotal shaft; a pair of swingable arms are positioned at two sides of the supporting rod and pivotally suspended from the first pivotal shaft; a pair of cranks are pivotally installed from the second pivotal shaft; front ends of the pair of treading rods are pivotally connected to the lower ends of the arms, respectively;
each side of the first pivotal shaft is firmly secured with an angle adjusting plate which is at an inner side of the arm; a lower side of the angle adjusting plate is installed with a plurality of positioning holes; each arm is installed with a button at a position with respect to a selected positioning hole of the angle adjusting plate; the button has an insertion shaft which has a size smaller than the size of the positioning hole; thereby, adjusting the button causes the shaft to be inserted into one of the positioning hole;
thereby, when the insertion shaft of the button is adjusted to position in one of the positioning hole, the arm is positioned; the treading rods move reciprocally with the treading actions of the user; if the insertion shaft of the button is inserted into another positioning hole, the moving range of the treading rods will change so as to adjust the difficulty in exercise; when the shaft of the button is adjusted to move out of the positioning hole, the arm freely moves forwards and backwards; as the pulley slides to a buckle groove at a distal end of the guide groove, by the cranks to move along a round trace, the treading rods are drive to move along an elliptical trace.