Swivel a decoupled central ring member

A swivel comprising:

• an inner ring and an outer ring,
• the inner and outer rings being coaxial and rotatable relative to one another around a central axis,
• the inner and outer rings defining a toroidal chamber having an inner chamber surface and an axial seal annulus gap between the inner and outer rings,
• a bearing structure comprised of an upper bearing structure and a lower bearing structure on each side of the toroidal chamber,
• the inner and outer rings being rotatably interconnected via the bearing structure,
• each of the upper bearing structure and the lower bearing structure interconnecting the inner and outer rings,
• the axial seal annulus gap extending from the toroidal chamber to the bearing structure,
• an upper sealing member and a lower sealing member being situated in the seal annulus gap near a respective upper and lower bearing structure,
• wherein at least one of the inner and outer rings is comprised of an upper ring member, and a lower ring member of L-shaped cross section with each upper and lower ring member having a radially extending leg and an axially extending leg that defines a part of the inner chamber surface, and a central ring member defining a further part of the inner chamber surface and contacting the axially extending legs with an axial surface along an interface gap which interface gap extends from the toroidal chamber along the axially extending legs and is situated at a radial distance from the annulus gap, the central ring member having and with a radial interface planes that extend from the interface gap along the radially extending legs of the upper and lower ring members,
• the upper and lower ring members being fixedly attached to the respective upper and lower bearing structures and the central ring member being independently displaceable relative to the upper and lower ring members in an axial direction along the interface gap.