Cylinder lock with rotatable pins

A locking system comprising a cylinder lock of a type having rotatable pins which must be rotated to a given rotational position to effect unlocking thereof, and a key for use therewith, said cylinder lock comprising:

• (a) a cylinder housing defining a bore;
• (b) a plug deployed within said bore, said plug having a longitudinal axis and defining a keyway and at least one pin channel communicating with said keyway;
• and
• (c) at least one pin disposed in said at least one pin channel so as to be displaceable along, and rotatable about, a pin axis, said pin having an engagement end proximal to said keyway,
• wherein said engagement end is formed with at least two engagement features projecting parallel to, but displaced from, said pin axis, said at least two engagement features being separated by at least one depression, and wherein said pin is free to rotate through 360° about said pin axis, said engagement features being terminated in rounded end portions, said key comprising:
• a key shaft configured for insertion into said cylinder lock along said keyway in a direction of insertion, said key shaft having at least one pin-engaging face which features a plurality of recessed seats, each of said plurality of recessed seats being configured to rotate said at least one pin to any given rotational position relative to said direction of insertion,
• wherein each of said plurality of recessed seats is formed with at least two similar conical depressions intersecting along a line so as to form an intermediate ridge,
• said intermediate ridge being capable of contact with said engagement features only at a contact point which subtends a relatively very small angle with respect to said pin axis,
• such that at said contact point, any resting position of said engagement features on said ridge is unstable, causing said engagement features to slide into proper engagement within said conical depressions.