Patent ID: 7320392

Claim:
A coupling device for a shaft, comprising: a coupling disk coupled to an out-extending shaft; a disk coupled to an external force member; a first concave-convex assembly which is with the disk and has a first helicoid engaging surface; a second concave-convex assembly which is engaged with the coupling disk and has a second helicoid engaging surface engaged with the first helicoid engaging surface; and a force generating source member provided between the coupling disk and the disk, wherein: the first and second concave-convex assemblies are positioned to be pressed against and engaged with each other, and wherein at least one of the first and second concave-convex assemblies is movable relative to the other to effect a rotational angular displacement and an axial displacement relative to the other; the first concave-convex assembly and the disk are positioned to be pressed against and engaged with each other, with at least one of the first concave-convex assembly and the disk being movable relative to the other to effect a rotational sliding angular displacement between the first concave-convex assembly and the disk; an external force association member is positioned between the first concave-convex assembly and said external force member, and the external force association member and the first concave-convex assembly are positioned to be pressed against and engaged with each other in a radial direction, and wherein at least one of the external force association member and the first concave-convex assembly is movable relative to the other to effect an axial sliding displacement between the external force association member and the first concave-convex assembly; and upon action of the force generating source member, the disk is coupled with the out-extending shaft via the coupling disk so that the external force member and the out-extending shaft are coupled.