Nut and snap ring position locking device

A position locking device for use with an externally-threaded round shaft having at least one axial keyway of rectangular cross-section, comprising:

• an internally-threaded nut disposed to engage with the externally-threaded shaft, said nut having a proximate end face and a circumferential groove oriented perpendicular to the nut internal thread axis, said groove having a cylindrical groove bottom surface concentric with the axis of said internal thread and a proximate groove wall surface and a distal groove wall surface each groove wall surface being substantially perpendicular to said groove bottom surface, said nut further having at least one parallel-walled flat-bottomed radial slot running across the proximate end face in a direction radially outward from the nut internal thread axis with the flat bottom parallel to the plane of said circumferential groove and of depth extending from said proximate end face to the distal wall of said groove;
• and
• a flat planar snap ring of generally semi-circular shape being symmetric about a central base region, having two symmetrically-opposed inwardly-curving arms extending outward from said base region and having a flat-tipped straight tang centered between said arms and extending from said base region in the direction toward the arm tips, said arms disposed to engage the nut circumferential groove with the arm tips gripping the groove bottom surface and said tang disposed to engage with and extend through a nut radial slot to engage with an axial keyway of a shaft engaged with said nut.