US Patent 7226391 Elliptical exercise device

An elliptical exercise device includes a main frame having a rotary shaft defining an axis, left and right link rods having rear ends connected to the rotary shaft for rotation about the axis, left and right arms connected respectively to front ends of the link rods for reciprocal movement, and left and right foot plates connected pivotally and respectively to the link rods and movable along elliptical paths when the rear ends of the link rods rotate. A guide mechanism is connected to the foot plates and the main frame to restrict movement of the foot plates. Each foot plate is substantially horizontal when moving upward or downward from the lowest or highest point of the corresponding elliptical path.