US Patent 7243953 Coupling apparatus including release preventing structure

A coupling apparatus includes a pair of cylindrical coupling main bodies which are concentrically and oppositely arranged to each other and which have the same structure as to each other, liners which are accommodated in the coupling main bodies respectively, and a release preventing structure which can selectively resist a rotational force applied to the coupling main bodies coupled with each other, so that a coupling of the coupling main bodies is maintained.