Patent ID: 7654535

Claim:
Apparatus for spacing two relatively rotatable facing surfaces in use by entraining gas between the surfaces, the apparatus including: a first portion defining a generally frusto-conical surface; a second portion defining at least one flat surface disposed immediately adjacent the first portion so that the two surfaces face each other and define a point or a line of closest engagement between the surfaces, with a diverging gap extending between the surfaces on one side of a plane which contains the point or line of closest engagement and with a converging gap extending between the surfaces on another side of said plane, the gaps extending in a substantially circumferential direction relative to the two rotatable facing surfaces; a device for biasing the flat surface towards the frusto-conical surface about a pivot center to maintain the gaps within a predetermined dimensional range; an axially moveable tile carrier defining a radial sealing surface for forming, with a further radial sealing surface, a radial seal to separate internal and external pressure areas and an axially sealing surface cooperating with an axially slidable seal to separate internal and external pressure areas whereby a radial location of the seal is selected such that the pressure applied by the internal and external pressure areas to the radial sealing surface is substantially balanced by at least the internal and external pressures applied to respective pressure-balancing surfaces opposing the radial sealing surface; and a piston ring between the sealing surface and the seal, wherein the tile carrier is provided with a cylindrical sliding surface containing a groove into which is fitted a piston sealing ring, the sliding surface and the piston sealing ring cooperating with a cylindrical bore formed in a seal static back member such that the cylindrical bore together with the cylindrical surface and the tile carrier define a closed annular space, the apparatus further including a valve for venting the enclosed gas space.