Abstract: A padlock comprises a battery-powered, built-in alarm which operates when the padlock's shackle is severed or forced open. The battery and alarm can be tested by opening the lock with a key, rotating the short leg of the shackle away from the lock body and then depressing the shackle, or optionally, by depressing the short leg. The alarm is turned on in response to the momentary closing of a switch when one shackle leg moves outwardly upon severance or forcible opening. The alarm may be an audible signal or an inaudible signal transmitted as a radio wave to a remote receiver at which an audible or visible signal is actuated. The audible signal generated at the lock escapes from the lock body through sound ports. Both audible and inaudible signals may be generated at the lock simultaneously.

Abstract: A padlock contains a battery connected by electrical circuitry and switches to an alarm sounding device which sounds an alarm when someone attempts to force open or sever the lock shackle or when someone attempts to remove the battery in an unauthorized manner. A test signal of momentary duration is automatically sounded each time the lock is opened or closed in an authorized manner, and this indicates whether the alarm system is operative.