COUPLING UNIT

There is disclosed a coupling unit (100) for transmission of a rotary driving force, comprising a first coupling member (110) having a curved first bearing surface (116) and a second coupling member (150) having a main coupling body (154) and a curved second bearing surface engaging the first bearing surface thereby enabling rotation of the second coupling member (150) relative to the first coupling member (110). The second coupling member comprises at least two carrying elements (158) which are each provided with a respective one of at least two second bearing surface segments (160) of the second bearing surface that engage the first bearing surface. At least two connecting elements (156) of the second coupling member (150) each connect a respective one of the at least two carrying elements (158) with the main coupling body (154) and comprise an elastically deformable material. In a first deformed condition the elastically deformable material provides a first biasing force urging the at least two second bearing surface segments (160) into contact with the first bearing surface. A blocking element (120) of the first coupling member (110) is arranged between the first bearing surface (116) and the main coupling body (154) and is configured to prevent passage of the carrying elements (158) along the blocking element at least in the first deformed condition. In a second deformed condition of the elastically deformable material, wherein the elastically deformable material provides a second biasing force larger than the first biasing force, the carrying elements (158) are able to pass along the blocking element.