Hydraulic machine

Apparatus comprising:

• a hydraulic machine that includes
• a hydraulic fluid flow directing arrangement including a generally cylindrical spool,
• wherein the spool is rotatable in axially fixed rotatable relation within a cylindrical bore of the machine,
• wherein the spool includes
• a pair of axially disposed first and second radially inward extending circumferential grooves,
• wherein each circumferential groove is bounded radially inward by a respective bottom wall,
• a plurality of angularly spaced radially inward extending first axial grooves,
• wherein each first axial groove extends
• axially intermediate of the first and second circumferential grooves, and
• in intersecting relation with the first circumferential groove and not the second circumferential groove,
• a plurality of angularly spaced radially inward extending second axial grooves,
• wherein each second axial groove extends
• axially intermediate of the first and second circumferential grooves, and
• in intersecting relation with the second circumferential groove and not the first circumferential groove,
• wherein each first axial groove extends angularly intermediate of an immediately angularly adjacent pair of second axial grooves,
• wherein the respective bottom wall of the first circumferential groove in transverse diametric cross section extends further radially outward from the axis with axial proximity to the first axial grooves.

Apparatus comprising:

• a hydraulic machine including a hydraulic fluid flow directing spool,
• wherein the spool is in fixed axial and rotatable relation within a bore of the machine,
• wherein the spool extends along an axis and includes
• an axially extending recess,
• wherein the axially extending recess includes an annular internal splined portion, wherein splined portion is configured to operatively engage a rotatable shaft,
• a generally cylindrical outer surface, wherein the outer surface includes
• a radially inward extending first circumferential groove,
• a radially inward extending second circumferential groove,
• wherein the first circumferential groove is axially disposed from the second circumferential groove,
• wherein at least one of the first circumferential groove and the second circumferential groove extends in at least partially radially outwardly overlying relation of the splined portion,
• a plurality radially inward extending angularly spaced first axial grooves,
• wherein each of the first axial grooves
• intersects with the first circumferential groove and not the second circumferential groove,
• a plurality of radially inward extending angularly spaced second axial grooves,
• wherein each of the second axial grooves
• is positioned angularly intermediate of an angularly immediately adjacent pair of first axial grooves, and
• intersects with the second circumferential groove and not the first circumferential groove,
• wherein the first circumferential groove in transverse diametric cross section is bounded radially inward by a first bottom wall,
• wherein the second circumferential grove in transverse diametric cross section is bounded radically inward by a second bottom wall,
• wherein the respective first bottom wall or second bottom wall of at least one of the first circumferential groove or the second circumferential groove that extends in at least partially radially outward overlying relation of the splined portion, extends further radially outward from the axis with axial proximity to the respective intersecting first axial grooves or second axial grooves.