Lockdown cylinder locks

A lock cylinder, comprising:

• a shell defining a generally cylindrical chamber having an inner surface and a longitudinal groove at least partially defined by a tapered surface extending radially outward from the inner surface;
• a plug rotatably mounted in the chamber for rotation between a home position and a rotated position, the plug defining:
• a longitudinally-extending keyway;
• at least one pin cavity connected with the keyway;
• and
• a longitudinal pocket in communication with the pin cavity, wherein the longitudinal pocket is aligned with the longitudinal groove when the plug is in the home position;
• a sidebar movably mounted in the pocket for movement between a radially inward position and a radially outward position, wherein the tapered surface of the shell is configured to urge the sidebar toward the radially inward position as the plug rotates from the home position to the rotated position, and wherein rotation of the plug from the home position is blocked when the sidebar is prevented from moving to the radially inward position;
• and
• at least one pin seated in a corresponding one of the at least one pin cavity, each pin comprising a first leg facing the keyway and a second leg facing the longitudinal pocket, wherein each second leg comprises a plurality of notches, wherein each notch is configured to permit radially inward movement of the sidebar when aligned with the sidebar, each pin having a blocking position in which no notch of the pin is aligned with the sidebar and the pin blocks movement of the sidebar from the radially outward position, each pin having a plurality of unblocking positions in which a corresponding one of the notches is aligned with the sidebar and the pin does not prevent radially inward movement of the sidebar;
• wherein the second leg of each pin extends from the first leg of the pin in a first direction transverse to the keyway and a second direction opposite the first direction;
• and
• wherein each pin is symmetrical relative to the keyway and has an H-shaped cross-section.

A system, comprising

• a lock cylinder, comprising:
• a shell;
• a plug rotatably mounted in the shell for rotation between a home position and a rotated position, the plug defining a keyway;
• a sidebar movably mounted to the plug and configured for movement between a radially outward position and a radially inward position, wherein rotation of the plug from the home position is prevented when the sidebar is maintained in the radially outward position;
• and
• a pin having a blocking position and a plurality of unblocking positions, the pin comprising a plurality of notches;
• wherein, with the pin in the blocking position, none of the notches are aligned with the sidebar and the pin maintains the sidebar in its radially outward position, thereby preventing rotation of the plug relative to the shell;
• and
• wherein, with the pin in each of the unblocking positions, a corresponding one of the notches is aligned with the sidebar such that the pin does not prevent movement of the sidebar to its radially inward position;
• and
• a family of keys comprising a plurality of keys, each key of the key family configured for insertion into the keyway and comprising a bitting profile including a first bitting that engages the pin upon insertion of the key into the keyway, wherein each key has a different root depth at the first bitting such that each key places the pin in a different one of the unblocking positions upon insertion of the key into the keyway;
• wherein the plurality of notches comprises five of the notches such that the plurality of unblocking positions comprises five of the unblocking positions.