Patent ID: 6846261

Claim:
A sun gear member for prolonged, low friction operational use in a planetary gearset in combination with at least one planet gear adapted for prolonged operational use within said planetary gearset, the sun gear member comprising: a sun gear body made of a steel material and having an outer periphery with a plurality of teeth formed thereon, each said sun gear tooth having at least one mating surface for engaging mating surfaces on complementary teeth on said at least one planet gear; and a fatigue-resistant coating applied to said mating surfaces of said sun gear teeth, said coating being harder and more abrasive than the mating surfaces of the planet gear teeth, wherein said coating is formed of a first layer applied to said mating surfaces of each said gun gear tooth and a second layer disposed on said first layer, wherein said second layer is adapted to contact the mating surfaces of the planet gear teeth and wherein said first layer is a metallic material and said second layer is a ceramic material, wherein the coating comprises a plurality of outwardly projecting abrasive tips contacting the mating surfaces of the planet gear teeth prior to an initial run-in period and wherein following the initial run-in period, the sun gear teeth and the planet gear teeth operate with lubricating oil therebetween in a substantially full-film, elasto-hydrodynamic lubrication regime for an extended life cycle of the planetary gearset.