Abstract: A bearing seal assembly includes a pair segmented circumferential or a carbon ring seals to contain oil in the bearing compartments of a gas turbine engine or other mechanical device. The pair of seals, an oil-side seal and an air-side seal, are axially-spaced between the oil and the air in the housing. Air at an elevated pressure is introduced between the seals. This elevated air pressure urges the seals axially apart from one another and radially inward to improve the seal. A backup seal is provided adjacent either the oil-side seal or the air-side seal. In the event of failure of either the oil-side seal or the air-side seal which results in the loss of air pressure, the backup seal will provide at least a minimum level of seal between the oil compartment and the air in the housing.

Abstract: In a twin spool gas turbine engine, a bellows serves to bias a carbon seal against its seal plate and a piston ring back-up seal spaced radially outward and axially from the carbon seal provides a controlled leak path in the event the bellows fails.

Abstract: In a gas turbine engine the vent for the bearing compartment has a restriction therein to control the airflow from the compartment and this restriction is variable in response to an engine parameter so as to control the pressure drop across the air seals for the compartment.

Abstract: A ring fabricated from metal whose modulus of elasticity is higher than and its coefficient of expansion is lower than the outer race of a roller bearing that supports concentrically mounted shafts of a turbine power plant serves to restrain growth owing to the different thermal and centrifugal forces imposed by each of said shafts otherwise causing the roller of the bearing to loosen.