Flexible joints

Claim 1

A flexible joint for use with apparatus subject to both constant angular displacement and an internal/external pressure differential, said joint comprising an annular female member, an annular male member within said annular female member, and an annular connecting member located between said male member and said female member and forming a connection between said male member and said female member, said connection including first and second coupling means, said first coupling means comprising a first part spherical annular cylinder generally U-shaped in radial section and having annular open and closed ends, a first part spherical annular piston positioned within said first cylinder for relative angular movement, a first sealing liquid in said first cylinder between said first piston and said first cylinder closed end, cooperating first sealing means on said first piston and said first cylinder sealing said first cylinder against escape of said first sealing liquid, and the initial relative positions of said first piston and said first cylinder and the depth of said first cylinder being one wherein when said first piston is moved to an angular position relative to said first cylinder said first piston engages said first cylinder closed end prior to a diametrical portion of said first piston exiting from said first cylinder thereby maintaining said first piston within said first cylinder and the seal between said first piston and said first cylinder; and said second coupling means comprising a second part spherical annular cylinder generally Ushaped in radial section and having annular open and closed ends, a second part spherical annular piston positioned within said second cylinder for relative angular movement, a second sealing liquid in said second cylinder between said second piston and said second cylinder closed end, cooperating second sealing means on said second piston and said second cylinder sealing said second cylinder against escape of said second sealing liquid, and the initial relative positions of said second piston and said second cylinder and the depth of said second cylinder being one wherein when said second piston is moved to an angular position relative to said second cylinder said second piston engages said second cylinder closed end prior to a diametrical portion of said second piston exiting from said second cylinder thereby maintaining said second piston within said second cylinder and the seal between said second piston and said second cylinder.