Patent ID: 7249769

Claim:
A seal for providing sealing between at least two separate and differing pressure zones each exposed to differing sources of pressure and between a rotating structure and a non-rotating structure, said rotating structure having a high pressure side and an opposite, low pressure side and comprising first and second sealing means, the first sealing means comprising first and second seal lands positioned either side of a rotating seal member, said seal lands being connected together via connecting means, said connecting means being movably mounted on said non-rotating structure and arranged to be moveable so as to accommodate relative movement of said rotating and non-rotating structures, said second seal means being arranged and positioned to provide a seal between said non-rotating structure and the first seal land and being positioned between said high and low pressure zones such that the pressure around the first seal land is controlled, said first seal land and the non-rotating structure defining a first chamber, the first chamber being permanently connected to the high pressure zone, the connecting means and the first and second seal lands defining a portion of a second chamber, the at least a portion of the connecting means and the at least one of the first and second seal lands being imperforate such that the first chamber is isolated from the second chamber, said connecting means comprising a yoke which is flexibly attached to the non-rotating structure.