Treading exercise machine with elliptical trace

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.