Key retaining cylinder for a lock

Abstract From the Canadian patent

A key retaining cylinder lock device has a cylinder body with a bore therein extending along an axis. A plug is rotatable in said bore about the axis and is confined against axial translation. The plug has an axially extending keyway therein open to said bore and adapted to receive a key having an edge notch partly defined by an inner wall extending at least partially transversely of said axis. The plug also has a circumferential groove open to the keyway and open to a chamber in part defined by a plug chordal surface laying on both sides of the keyway and substantially perpendicular to the plane of symmetry of the keyway. In the groove and chamber is a partial ring having a central, …