Abstract: A plunger type lock comprising a barrel with an axial bore, locking members in the form of balls housed in the barrel wall and extensible outwardly from the barrel by a plunger axially slidable within the barrel bore, at least one further ball housed in an opening in the wall of the plunger and extensible outwardly therefrom and a peripheral groove on the inner wall surface of the barrel for receiving the further ball, the further ball being forceably moved and held in the barrel's groove by an incorrect key, instrument or an implement to prevent and resist movement of the plunger whenever an unauthorized attempt to operate and open the lock is made.

Abstract: A register pointer for an electric utility meter is described as having a weakened section at which fracture can occur to break away the pointer when an attempt is made to tamper with the pointer, such as by manually resetting the pointer's position on the register to show a lower reading of energy consumption. Various forms of breakaway means are described which will permit separation of the pointer portion of the device from its shaft portion when a torque is applied to the pointer end.

Abstract: A plunger type lock construction in which the key receiving face thereof is spaced a critical distance from a portion of a reciprocable plunger which is within the lock body and which is engaged by the key to release locking members extending from the lock body. The lock body has shaped means at its key receiving face which prevents insertion of a key to the proper, lock operating depth in the lock if the end of the key which faces the key receiving face is not shaped so as to receive the shaped means on the lock body. Each lock may have a differently shaped means so that a key which will fit one lock will not fit another lock, but a master key may be provided which will fit all or only a plurality, of such locks.

Abstract: A preformed, thin metal printing plate is provided which permits the plate to snap on and lock to the printing cylinder of an offset printing device so that the plate is juxtapositioned the cylinder along the entire plate area between a leading edge of the plate and a reverse bend part of a trailing edge of the plate.

Abstract: A plunger-type (barrel) lock has a spring loaded plunger which can only be properly retracted by the use of a key having a central rod, enlarged end sliding member and outwardly moving fingers for gripping engagement within a socket (cylinder bore) of the plunger. A movable, spring-biased eyelet is positioned adjacent the socket, such that an unauthorized key or tampering tool will grip the eyelet, rather than the plunger socket, failing to open the lock. The key has a toggle type operating lever including a tension relief element in the form of a spring, coacting with an internal collar of the key to allow some axial movement of the key's operating elements. Use of the collar allowing axial movement of the key's operating elements and complementing socket diameter of the plunger within the lock can provide security lock combinations for the user(s).

Abstract: Attempts to pick the plunger-type (barrel) lock disclosed are frustrated by the necessity of holding one axially movable part in place against the force of a spring while retracting another axially movable member to open the lock. The key that opens the lock has a central pin stationary in use for holding back a position while radially spreading fingers frictionally engage and thereby permit withdrawal of an axially movable cylinder coaxial with the piston. A frangible member is provided for installing the lock without using the special key so that the number of keys can be strictly controlled. The key will open not only the lock of this invention, but also other kinds of plunger-type locks in common use by gas and electric utility companies.