A seal assembly for sealing between a central shaft and outer member disposed about the shaft, the seal assembly comprising: an outer annular case disposed within and coupled with the outer member; an annular flexible seal disposed within and coupled with the case and having at least one elastomeric sealing lip engageable with an outer circumferential surface (1a; 19A) of the shaft or of a sleeve disposed about the shaft; an inner annular rigid seal disposed at least partially within the outer case and having an inner radial end that is spaced axially from the sealing lip, and an outer radial end; an outer annular rigid seal; and a biasing member configured to bias the outer rigid seal toward the inner rigid seal such that the outer rigid seal sealingly engages with the inner rigid seal; wherein: the outer member is rotatable about an axis (Ac) extending through the shaft such that the outer annular case and the annular flexible seal coupled with the case is rotatable about the central axis (Ac); characterized in that: the inner radial end of the inner annular rigid seal is coupled with the shaft or with the sleeve; the outer radial end is slidably disposed against the flexible seal such that the flexible seal is radially displaceable relative to the inner rigid seal when the outer member displaces radially with respect to the shaft; and the outer annular rigid seal is disposed about the inner rigid seal, is coupled with the outer annular case so as to be angularly displaceable about the central axis (Ac) and has an inner end sealingly engaged with the inner rigid seal. an outer annular case disposed within and coupled with the outer member; an annular flexible seal disposed within and coupled with the case and having at least one elastomeric sealing lip engageable with an outer circumferential surface (1a; 19A) of the shaft or of a sleeve disposed about the shaft; an inner annular rigid seal disposed at least partially within the outer case and having an inner radial end that is spaced axially from the sealing lip, and an outer radial end; an outer annular rigid seal; and a biasing member configured to bias the outer rigid seal toward the inner rigid seal such that the outer rigid seal sealingly engages with the inner rigid seal; wherein: the outer member is rotatable about an axis (Ac) extending through the shaft such that the outer annular case and the annular flexible seal coupled with the case is rotatable about the central axis (Ac); characterized in that: the inner radial end of the inner annular rigid seal is coupled with the shaft or with the sleeve; the outer radial end is slidably disposed against the flexible seal such that the flexible seal is radially displaceable relative to the inner rigid seal when the outer member displaces radially with respect to the shaft; and the outer annular rigid seal is disposed about the inner rigid seal, is coupled with the outer annular case so as to be angularly displaceable about the central axis (Ac) and has an inner end sealingly engaged with the inner rigid seal. the inner radial end of the inner annular rigid seal is coupled with the shaft or with the sleeve; the outer radial end is slidably disposed against the flexible seal such that the flexible seal is radially displaceable relative to the inner rigid seal when the outer member displaces radially with respect to the shaft; and the outer annular rigid seal is disposed about the inner rigid seal, is coupled with the outer annular case so as to be angularly displaceable about the central axis (Ac) and has an inner end sealingly engaged with the inner rigid seal.