A screw assembly comprising: a screw shaft having a helical thread profile; and a nut for mounting around said screw shaft ; the screw assembly further comprising a first seal and a second seal , wherein each of said first seal and said second seal independently comprises a seal of the type comprising: a seal body having an inner surface for mounting onto and sealing against a screw shaft ; an internal chamber formed within said seal body , wherein one or more openings are provided on said inner surface to allow lubricant material to transfer between said inner surface and said internal chamber ; and one or more external ports provided on a radial surface and/or an outer surface of said seal body for transferring lubricant material into or out of said internal chamber of said seal body ; characterized in that respective external ports of said first and second seals are each aligned with a respective passage formed within said nut , the passage(s) extending through said screw assembly to provide a re-circulating path for re-circulating lubricant material within said screw assembly, and in that the re-circulating path extends from the first seal through the passage(s) formed within the nut to the second seal . a screw shaft having a helical thread profile; and a nut for mounting around said screw shaft ; the screw assembly further comprising a first seal and a second seal , wherein each of said first seal and said second seal independently comprises a seal of the type comprising: a seal body having an inner surface for mounting onto and sealing against a screw shaft ; an internal chamber formed within said seal body , wherein one or more openings are provided on said inner surface to allow lubricant material to transfer between said inner surface and said internal chamber ; and one or more external ports provided on a radial surface and/or an outer surface of said seal body for transferring lubricant material into or out of said internal chamber of said seal body ; characterized in that respective external ports of said first and second seals are each aligned with a respective passage formed within said nut , the passage(s) extending through said screw assembly to provide a re-circulating path for re-circulating lubricant material within said screw assembly, and in that the re-circulating path extends from the first seal through the passage(s) formed within the nut to the second seal . a seal body having an inner surface for mounting onto and sealing against a screw shaft ; an internal chamber formed within said seal body , wherein one or more openings are provided on said inner surface to allow lubricant material to transfer between said inner surface and said internal chamber ; and one or more external ports provided on a radial surface and/or an outer surface of said seal body for transferring lubricant material into or out of said internal chamber of said seal body ; characterized in that respective external ports of said first and second seals are each aligned with a respective passage formed within said nut , the passage(s) extending through said screw assembly to provide a re-circulating path for re-circulating lubricant material within said screw assembly, and in that the re-circulating path extends from the first seal through the passage(s) formed within the nut to the second seal . <EOS>