selectively engaged with one or more of cams 40 42 and 44 although follower 48 is depicted it should be recognized that numerous follower mechanisms may be operable to select one or more of cams 40 42 and 44 the other end of follower 48 may be engaged with a piston of fuel pump 16 selection mechanism 50 may be a conventional hydraulic mechanism that may selectively lock inner follower 52 within outer follower 54 as depicted in fig2 when inner follower 52 is locked within outer follower 54 follower 48 may translate motion to a piston of fuel pump 16 relative to the rotation of outer cams 40 and 44 when inner follower 52 is not locked within outer follower 54 follower 48 may translate motion to a piston of fuel pump 16 relative to the rotation of inner cam 42 outer cams 40 and 44 may have a lobe profile with four lobes while inner cam 42 may have a lobe profile with two lobes when shaft 46 rotates follower 48 may be displaced relative to the lobe profile of the cam that follower 48 is engaged with such that a piston of fuel pump 16 completes a stroke for each lobe referring now to fig3 a profile view of outer cams 40 and 44 about shaft 46 is depicted outer cams 40 and 44 may have a 4 lobe profile with each set of opposing lobes having a generally oval shape when in communication with outer cams 40 and 44 follower 48 may be fully displaced to stroke a piston of fuel pump 48 four times for each revolution of shaft 46 referring now to fig4 a profile view of inner cam 42 about shaft 46 is depicted inner cam 42 may have a generally.