Sealing assembly

A sealing assembly for sealing between two relatively rotatable cylindrical surfaces, comprising:

• a groove in at least one of said cylindrical surfaces, said groove having an inner wall,
• a radially outer seal part and a radially inner seal part disposed in said groove so that said radially outer seal part is disposed radially outwardly of said radially inner seal part, said radially outer seal part having a radially outer seal face adapted to sealingly engage one of said surfaces and a radially inner face adapted to engage said radially inner seal part, said radially inner seal part having a radially inner seal face adapted to sealingly engage the other of said surfaces and a radially outer face adapted to engage said radially outer seal part, said radially inner seal part being disposed between said radially inner face of said radially outer seal part and said inner wall of said groove,
• said groove being configured so that it has a non-uniform radial depth,
• said radially inner seal part being movable axially relative to said radially outer seal part in response to fluid pressure from a radially deeper portion of said groove towards a radially shallower portion to effect setting of the sealing assembly,
• said groove and said seal parts being so dimensioned that said seal parts become compressed between the surfaces during setting of the sealing assembly, and
• cooperable means disposed on said radially outer seal part and said radially inner seal part for preventing substantial release of compression of said seal parts once the sealing assembly has been set.