Shaft internal lubrication with rifling grooves

1. A method of providing internal shaft lubrication, the method comprising:

drip feeding a lubricant to a feed tube within a central bore of a shaft body;

urging the lubricant along a lubrication flow path comprising at least one rifling groove on an inner wall of the shaft body formed by the central bore and a plurality of lubrication holes axially distributed along the shaft body that fluidically connects the inner wall with an outer wall of the shaft body; and

spraying the lubricant out of the lubrication holes responsive to rotation of the shaft body.

2. The method of claim 1 , wherein the at least one rifling groove comprises two or more riffling grooves, and each of the two or more riffling grooves contacts a different subset of the lubrication holes.

3. The method of claim 1 , wherein spraying the lubricant out of the lubrication holes provides splash lubrication to a plurality of components coupled or proximate to the shaft body.

4. The method of claim 1 , wherein the feed tube is configured to receive the lubricant from an excess lubricant supply collected in a passage formed substantially perpendicular to an axis of rotation of the shaft body.

5. The method of claim 4 , further comprising collecting the lubricant splashed upon exiting the shaft body by a scupper, wherein the scupper is in fluid communication with the passage to provide the lubricant collected.

6. The method of claim 4 , wherein the passage is a vertical column in a gearbox housing, and the lubrication flow path within the bore is a substantially horizontally oriented spiral configured to urge the lubricant toward a driven end of the shaft body.

7. The method of claim 1 , wherein the lubricant is urged along the lubrication flow path via centrifugal forces acting on the lubricant due to rotation of the shaft body.