Abstract: There is a gear set. The gear set has a) a first gear having a first surface and b) an intermeshing second gear having a second surface. The first and second surfaces each, independently, have an isotropic arithmetic mean roughness, Ra, of about 0.0762 micrometers/3 microinches or less and are lubricated. There is also a method for increasing the contact surface-fatigue life of a gear set.

Abstract: A surface processing method includes the step of increasing a surface hardness of a metal having a nominal composition that includes about 0.21-0.25 wt % carbon, about 2.9-3.3 wt % chromium, about 11-12 wt % nickel, about 13-14 wt % cobalt, about 1.1-1.3 wt % molybdenum, and a balance of iron from a first hardness to a second hardness. For example, the method is used to produce a surface-hardened component that includes a core section having a first hardness between about 51 HRC and 55 HRC and a case section having a second hardness that is greater than the first hardness.

Abstract: A power transmission system including a component having a surface and a plurality of micro-defects is provided. The surface has a distribution of asperities has a second resonance frequency distribution that is substantially outside of the resonance frequency distribution.

Abstract: A power transmission system and a method for enhancing the efficiency of such systems are provided. The system and method includes a lubricant having a viscosity from about 0.01 centistokes to about 400.00 centistokes, power transmission components with a contact surface finish of less than about 16 microinches, and coating the power transmission components with the lubricant during operation of the system.

Abstract: There is a gear set. The gear set has a) a first gear having a first surface and b) an intermeshing second gear having a second surface. The first and second surfaces each, independently, have an isotropic arithmetic mean roughness, Ra, of about 3 microinches or less and are lubricated. There is also a method for increasing the contact surface-fatigue life of a gear set.

Abstract: A power transmission system including a component having a surface and a plurality of micro-defects is provided. The surface has a distribution of asperities. The component has a first resonance frequency distribution. The distribution of asperities has a second resonance frequency distribution that is substantially outside of the first resonance frequency distribution.

Abstract: A surface processing method includes the step of increasing a surface hardness of a metal having a nominal composition that includes about 0.21-0.25 wt % carbon, about 2.9-3.3 wt % chromium, about 11-12 wt % nickel, about 13-14 wt % cobalt, about 1.1-1.3 wt % molybdenum, and a balance of iron from a first hardness to a second hardness. For example, the method is used to produce a surface-hardened component that includes a core section having a first hardness between about 51 HRC and 55 HRC and a case section having a second hardness that is greater than the first hardness.

Abstract: A method for improving acoustic and vibrational properties of gears includes determining the transmission errors of intermeshing gears due to stiffness variations in the gear teeth, performing Gear Tooth Topological (GTT) modifications to compensate for the errors, and isotropically processing the gears to produce an ultra-smooth surface finish. Additional errors from isotropic processing, machining, loading, thermal effects and/or load sharing may be summed with the errors from the stiffness variations and used for the GTT modifications. The teachings of the present invention may reduce noise by as much as 13 to 15 dB.

Abstract: A method for producing intermeshing gears having improved acoustic and vibration properties characterized by: examining the transmission errors due to mesh stiffness variations, performing Gear Tooth Topological (GTT) to compensate for such errors, and isotropic processing of the face surfaces of the gear teeth to produce an ultra-smooth surface finish.

Abstract: A spacer (10) for a helicopter main rotor shaft (102) is mounted in combination with the main rotor shaft (102) and is operative to support the inner race (116) of the upper bearing assembly (110) of the main rotor shaft (102) and is concomitantly operative to restrain axial migration of the inner race (116). The spacer (10) comprises a body member (11) having a stepped configuration defined by an upper cylindrical segment (12) and a lower cylindrical segment (20) to accommodate the outer structural envelope of the main rotor shaft (102). The upper cylindrical segment (12) includes an upper annular collar (14), an intermediate annular collar (16), and a lower annular collar (18), and the lower cylindrical segment (20) includes an interface annular collar (22) and a bottom annular collar (24).