A Hierarchy of Detail for Representing Non-Convex Curved Objects

This invention is relating to an improvement configured to a pushing caster of jogging machine. The body of jogging machine contains one master frame, one framework, one jogging board, one front transverse-rod, one hand holder, one rear floor-rod, etc. components. The transverse rod designed for master frame's base and front transverse-rod are fitted to the base of master frame where caster assemblies are plugged and retained at their both ends respectively. Diameter of caster is slightly bigger than diameter of rods. The inner sides of caster assembly, that is, the opposite direction that caster assembly face one another as they are installed at transverse-rod of master frame's base and front transverse-rod, is erected a positioning bushing to secure itself individually. Afterward, the outer circumference of each positioning bushing is enveloped by a floor-type rubber block which is in rectangular shape. This floor-type rubber block can be revolved around positioning bushing. Floor-type rubber block has been featured unequal thickness. It is designed to have its thickness bigger than diameter of caster assembly. Therefore, when the non-slip surface, that is, floor-type rubber block's bottom, contacts with floor surface, it will prop up the height of transverse-rod at master frame's base and the height of front transverse-rod because of the design feature. This prop will create a gap between each caster assembly and floor surface, and then disable caster's flnction. On the other hand, when floor-type rubber block is revolved to lose the contact between non-slip surface and floor surface, the thickness is small enough to reduce the height of transverse-rod at master frame's base and the height of front transverse-rod. The contact mechanism will be switched to caster assembly and floor surface instead. The machine body of jogging machine is ready for pushing movement.