Abstract: An "arrest" handcuff has the usual ratchet and pawl mechanism for closing the wrist aperture. In order to deadlock the pawl a runner is shifted by means of a manual push-button so that a stump on the runner then overlies a nose portion of the pawl. To release the deadlocking and pivot the pawl clear of the ratchet the runner must be shifted in the reverse direction, which movement is normally blocked by a lever pack operating on a stump extending from the runner. A correct key, however, can lift the levers and turn the runner back so that a further stump carried by the runner engages a tail portion of the pawl to lift it from the rathet. If the option to deadlock the pawl is not taken up in any particular arrest situation the pawl still remains engaged with the ratchet under a spring bias and the correct key is still needed to perform a reverse movement of the runner to lift the pawl from the ratchet.

Abstract: A security lock for use on sliding doors or gates has a pair of hook bolts which are thrown apart or withdrawn together according to the position of a head on a reciprocable slide. Each bolt has a recess mated to the head with front and rear driving surfaces, this geometry being related to the pivot points of the bolts such that the head drives the bolts positively between their thrown and withdrawn positions with no lost motion and without the need for spring-biasing of the bolts. The slide is deadlocked by a pack of levers, to which a second lever pack is linked, two lever packs being provided so that non-palindromic key-stepping can be employed. If required, the slide can be double-thrown by successive use of two different correct keys, for which different key-hole positions and are provided to cooperate with the lever packs.

Abstract: In a security door lock a pivoted detent deadlocks the bolt by engagement of a stump in pockets provided in the bolt. The detent is normally held in its locking position by a cam surface on the thrower and by a pack of detainers. Rotation of the correct key aligns notches in the detainers with a probe on the detent and also positions a second cam surface of the thrower adjacent to the detent, so the detent can pivot to its unlocking position under the action of a spring, and thereby free the bolt. After the bolt is shifted the final rotation of the key re-engages the cam surface against the detent to drive the detent positively back to its locking position. If required, the bolt can be double-thrown by a second ("master") key which lifts the detainers to higher positions so that second notches in the detainers now align with the detent probe. This higher lifting of the detainers also lifts a dogging slide so that the stump of the latter can pass over a projection on the bolt tail.

Abstract: A key-operated security lock of the kind including a key-identification mechanism, a thrower turned by the key and a deadbolt, has the deadbolt isolated from the thrower, and includes means operable only by correct identification of the key for connecting the thrower to the deadbolt and for removing a stop preventing retraction of the deadbolt from its extended position. The said means preferably includes a lever pivoted to the deadbolt and formed with a locking projection capable of engagement with a complementary recess in a runner driven along a path parallel with that of the bolt by co-operation with the thrower to connect the thrower to the deadbolt as a result of pivoting of the lever which is prevented by a further member in the form of a pivoted arm which holds the pivoted lever in a position such that its locking projection is clear of its recess until the pivoted arm is allowed to turn by the key-identification mechanism.