US Patent 10520096 Intershaft seal assembly

An intershaft seal assembly comprises an annular seal ring disposed between a pair of annular runners connected to a hollow outer rotating shaft, and a surface of a co-axial inner rotating shaft. The centrifugal force resulting from rotation of the hollow outer rotating shaft effects engagement of the annular seal ring with the surface of the co-axial inner rotating shaft. The surface may be a radially-inward-facing surface of a retaining arm connected to the co-axial inner rotating shaft.