Thrust force-compensating apparatus with improved hydraulic pressure-responsive balance mechanism

In a gas turbine engine having relatively rotatable first and second structures with respective annular cavities which face toward one another, an axial thrust force-compensating apparatus, comprising:

• (a) a first annular part mounted in said annular cavity of said first engine structure and having an annular end surface;
• (b) a second annular part mounted in said annular cavity of said second engine structure and having an annular end surface which opposes and faces toward said end surface of said first annular part;
• (c) primary hydraulic pressure balance means defined in said first annular part for providing separate outer and inner fluid flows through said first part to respective outer and inner regions between said end surfaces of said first and second parts at pressures responsive to the amount of separation existing between said end surfaces at said regions, said separate fluid flows at said pressures producing a film of fluid flowing between and in contact with said respective end surfaces which generates primary compensating moment forces acting on said end surfaces to maintain said end surfaces in generally parallel relationship;
• and
• (d) secondary hydraulic pressure balance means defined in said second annular part for producing secondary compensating moment forces which complement said primary compensating moment forces produced by said primary pressure balance means to limit the magnitude of any non-parallel relationship between said end surfaces of said first and second parts.