| 主权项 |
1. An ambulatory apparatus, comprising:
a plurality of cranks mounted rotatably in a body, wherein the body has an opening adjacent each of the cranks with top, bottom, left side, and right side lateral bearings defining the openings and wherein the left side bearing and the right side bearing each terminates in a radius to form a gap between the radii of the left side bearing and the right side bearing; and a plurality of legs, wherein each of the legs has a length dimension and a width dimension, and wherein a proximal end of each of the legs is connected to a respective one of the cranks and extends in a lengthwise direction of the leg through the opening to a distal end of the leg outside of the body in such a manner that the top, bottom, left side, and right side bearings bear on respective top, bottom, left side, and right side surfaces of the leg between the proximal end and the distal end in a manner that constrains movement of the leg in a lateral direction of the leg in the opening but allows the leg to move inwardly and outwardly in the lengthwise direction of the leg through the opening as the crank rotates, and wherein each leg has a width that varies between a concave curved left lateral side surface and a concave curved right lateral side surface positioned in the gap, wherein the shapes of the concave curved left lateral side surface and the concave curved right lateral side surface vary the width of the leg in a manner that provides practically zero clearance between the leg in the gap and the left side bearing and the right side bearing to maintain a fixed virtual pivot axis of the leg in the gap for more than one-half of a 360 degree rotation of the crank as the crank moves the leg inwardly and outwardly in the lengthwise direction of the leg through the opening. |
