Abstract: A tamper preventing tumbler lock which provides an alarm signal or prevents lock activation when any electrically conductive object, such as a pick or the like, is inserted in the keyway. The lock includes a pair of electrically conductive tumblers which complete an electrical path to activate the alarm or to activate a solenoid operated latch to prevent rotation of the lock cylinder or actuate an associated lock bolt when the conductive tumblers are bridged by the conducting object in the keyway. The lock may be operated as a conventional tumbler lock by means of an electrically non-conductive key.

Abstract: A detector lock assembly comprising a cylinder body having a spaced apart front and rear end with a bore therein extending along an axis and a plug rotatable in the bore on the axis with means defining a keyway in the plug and adapted to receive therein a key of a defined length and configuration to permit rotation of the plug relative to said cylinder body. Detection means is operatively associated with the cylinder body at the rear end thereof so as to establish an electrical circuit when a key or other object is inserted within the keyway that has a length that is less or greater than the defined length for the key.

Abstract: The invention provides a tamper-proof pin tumbler lock construction cooperative with an alarm means and protective against unauthorized picking or core drilling activities on the lock while securing normal key opening and closing procecures therefor. The construction energizes an alarm if the unauthorized activities exceed a predetermined time limit required for normal key opening and closing procedures.

Abstract: Alarm switch mechanism for an axial split-pin tumbler-type lock includes an electrical contact member disposed in the lock cylinder in the movement paths of lock tumbler elements and adapted for making an electrical contact with an element of any of the tumblers which is moved rearwardly or inwardly a predetermined distance, beyond the distance required for lock-opening purposes, means electrically insulating the contact member from the lock mechanism when no tumbler is in the latter position, and means adapted for making electrical connections to the tumbler elements and the contact member, respectively, whereby they may be connected in an alarm signal circuit closed by making said contact.

Abstract: A device for coupling a pressure vessel closure cap to an upper structure for supporting the reactor internals comprises a plurality of locking-keys which are guided in translational motion within radially disposed housings and can be moved into outwardly projecting positions by externally-controlled actuating means in order to engage in opposite recesses formed in the internal wall of the closure cap.