Vehicle power levels are increasing at a steady rate. Increased power dramatically reduces the life of drive train components, with the weakest area typically being the axle final drive planetary gear reduction. For example in some agricultural tractors the final drive planetary gear reduction is 6:875:1. The highest stress component is the sun gear. Typically, sun gears fail from pitting caused by very high compressive stresses on the tooth surface. Often packaging constraints in both diameter and width prevent gear designers from developing a new larger design to transmit the increased power. Standard gears are manufactured by a hobbing, shaving, and heat-treating operations. There can be considerable geometry distortion of the gear leads and profiles after heat-treatment. In addition, the surface doesn't have enough compressive residual stress to sustain a long life under severe loading. Accordingly there is a need in the art for a new gear manufacturing method that yields greater than a five time increase in sun gear durability, without changing the overall size of the existing planetary.
USPTO Backgrounds
USPTO Backgrounds