Ring-shaped coupling

A ring-shaped coupling comprising:

• an inner ring;
• a pair of outer rings which are placed facing each other in the axial direction and with a specified clearance therebetween, each having an inner circumferential surface consisting of a conical surface flaring toward the other;
• a rubber ring disposed between the inner ring and the pair of outer rings, said rubber ring having an inner circumferential surface which forms a single, solid surface and which adheres by vulcanization to an outer circumferential surface of the inner ring while an outer surface thereof is divided into two conical surfaces, which adhere by vulcanization to the respective conical inner circumferential surfaces of the outer rings, by a circular groove provided axially in the middle of and in the circumferential direction of the rubber ring, wherein the circular groove forms a circular gap leading to the clearance of the outer rings when the outer rings are fixed in place together with the rubber ring;
• and
• joining means having a cylindrical outer surface for putting said pair of outer rings close to each other in the axial direction and fixing them in place while compressing said rubber ring, and forming a circular air chamber leading outside between the inner surface thereof and the pair of outer rings, said circular groove communicating with said circular air chamber.