The locking device includes a key having a cylindrical shaft in which a guide groove is formed in the axial direction, and a cylinder lock which includes an outer cylinder, an inner cylinder, a locking bar and a tumbler, the inner cylinder has an inner cylinder main body rotatably accommodated in the outer cylinder, a rod fixed to the inner cylinder main body, and a key insertion slot, the locking bar is interposed between the inner cylinder main body and the outer cylinder and prevents the rotation of the inner cylinder by engaging and disengagingly locking the inner cylinder main body and the outer cylinder, and the tumbler has a guide convex portion engageably and detachably engaged with the key groove, and an inner concave portion rotatably received in the inner cylinder and dropping the locking bar.

The locking device includes a key having a cylindrical shaft in which a guide groove is formed in the axial direction, and a cylinder lock which includes an outer cylinder, an inner cylinder, a locking bar and a tumbler, the inner cylinder has an inner cylinder main body rotatably accommodated in the outer cylinder, a rod fixed to the inner cylinder main body, and a key insertion slot, the locking bar is interposed between the inner cylinder main body and the outer cylinder and prevents the rotation of the inner cylinder by engaging and disengagingly locking the inner cylinder main body and the outer cylinder, and the tumbler has a guide convex portion engageably and detachably engaged with the key groove, and an inner concave portion rotatably received in the inner cylinder and dropping the locking bar.

A bridge tumbler lock has tumblers that both slide and pivot, with their motion controlled by pairs of key interfaces. A sidebar is released to permit lock opening movement when all tumblers are in their correct positions. This results in a lock that is resistant to release of information due to partially correct key combinations occurring in the course of a lock picking attempt and thus enables enhanced security in an economical, effective lock construction.