A gas turbine engine according to an exemplary aspect of this disclosure includes, among other things, a compressor section, a combustor section, a turbine section, and at least one rotatable shaft. The gas turbine engine further includes a seal assembly including a static structure and a rotatable structure configured to meet to form a contact area. The seal assembly includes an abradable coating on one of the static structure and the rotatable structure, and the seal assembly further includes a cutter on the other of the static structure and the rotatable structure.

One aspect of the disclosure relates to a sliding member. The sliding member includes: a first sliding portion having a first lubricant placed between first parts of a first friction sliding mechanism; a second sliding portion having a second lubricant placed between second parts of a second friction sliding mechanism; and a third sliding portion having a third lubricant placed between third parts of a third friction sliding mechanism. The first sliding portion is in contact with the third lubricant, and the second sliding portion is not in contact with the third lubricant. The second lubricant contains an additive containing conductive carbon, and the third lubricant contains no conductive carbon. The second lubricant contains a relatively larger amount of the conductive carbon than the first lubricant.

A turbine engine strut stage extends through a gaspath upstream of a guide vane stage. A carbon seal system seals a bearing compartment and has: a carbon seal mounted to the case and a seal runner on the spool; and a seal carrier carrying the carbon seal. The engine passes buffer air along a buffer air supply path internally through one or more first struts of the stage of struts. The engine drains oil along an oil drain path internally through one or more second struts of the stage of struts.

A shaft characterized by its length to diameter ratio being less than about 1.75 having a drive connection at one end where the wall thickness of the shaft is selected to be thick enough to avoid ellipticalization strain error in torsional measurement of less than 5%. One specific application is for a crankset spindle that can be used to measure a cyclist right, left, and total leg torque.

A turbine engine strut stage extends through a gaspath upstream of a guide vane stage. A carbon seal system seals a bearing compartment and has: a carbon seal mounted to the case and a seal runner on the spool; and a seal carrier carrying the carbon seal. The engine passes buffer air along a buffer air supply path internally through one or more first struts of the stage of struts. The engine drains oil along an oil drain path internally through one or more second struts of the stage of struts.

A thrust foil bearing 40 having a thrust bearing surface S formed by arranging a plurality of leaves 42 side by side in a circumferential direction, in which each of the leaves 42 has a top foil portion Tf that forms the thrust bearing surface S, and a ratio of a circumferential length A of the top foil portion Tf of one of the leaves 42 at a radially central position of the top foil portion Tf, to a radial length B from an inner diameter-side edge 423 to an outer diameter-side edge 424 of the top foil portion Tf is 0.66 or less.

In order to effect a seal a porous material which comprises one side of two opposing surfaces is used to restrict and evenly distribute externally pressurized gas, liquid, steam, etc. between the two surfaces, exerting a force which is opposite the forces from pressure differences or springs trying to close the two faces together and so may create a non-contact seal that is more stable and reliable than hydrodynamic seals currently in use. A non-contact bearing is also disclosed having opposing surfaces with relative motion and one surface issuing higher than ambient pressure through a porous restriction, wherein the porous restriction is part of a monolithic porous body, or a porous layer, attached to lands containing a labyrinth, the porous restriction and lands configured to not distort more than 10% of a gap created from differential pressure between each side of the porous restriction.

A rotor shaft for a vertical take-off and landing (VTOL) aircraft having a rotor system includes a body having a first end connectable to the rotor system, a second end, and an intermediate portion defining an outer surface and an inner surface extending between the first end and the second end. The body is formed from a first material. A stiffness enhancing layer is applied to one of the outer surface and the inner surface. The stiffness enhancing layer includes a second material other than the first material. The second material has a modulus of elasticity that is about 16E6 psi (116 GPa) or greater.

A shaft characterized by its length to diameter ratio being less than about 1.75 having a drive connection at one end where the wall thickness of the shaft is selected to be thick enough to avoid ellipticalization strain error in torsional measurement of less than 5%. One specific application is for a crankset spindle that can be used to measure a cyclist right, left, and total leg torque.

A threaded installation is provided. The threaded installation includes a nut, a bolt, and a housing. The housing includes a threaded hole. A first threaded connection is formed where the bolt is threadably coupled with the nut, and a second threaded connection is formed where the bolt is threadably coupled with the threaded hole. The first threaded connection is characterized by a first flank angle, .sub.2A, of threads of the bolt or threads of the nut. The second threaded connection is characterized by a second flank angle, .sub.3B, of threads of the bolt or threads of the housing. The flank angles, .sub.2A and .sub.3B, satisfy the following equation:

[00001]$k_2=\frac{\cos \left({}_{2.Math.A}\right)}{\cos \left({}_{3.Math.B}\right)}>1.0.Math.0.$