Alarm Timers - Introduction

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Among the most important advances in twentieth-century bank security was the electric alarm system. These alarms were sometimes connected to a central monitoring location by telephone lines, but they always included a timer to disable the alarm at a predetermined time, avoiding false alarms. Today these alarm timers are often confused with time locks because they commonly include similar time movements. However, some familiarity with the most common formats of alarm timers will make them easily identifiable as the last part of the bank security equation to gain widespread acceptance. (1)

One could speculate that had the bank alarm system been perfected in the latter 19th century before the advent of the time lock, the adoption of the time lock may have taken much longer. Beginning in the mid 19th century safe a vault designs began to become so sophisticated at resisting drilling, prying and even explosives, that the time it took to defeat a safe began to increase to the point where it would take too long before the bank would be scheduled to open. Criminals then began to turn to the nighttime "masked robbery" where the bank or commercial proprietor or cashier were forced by gunpoint to open the safe after hours. A sophisticated alarm system would have made this more difficult. 

The fact that alarm timers needed the use of a reliable source of electricity, means that these could not have been employed before the commercial advent of the time lock in 1874.

American Bank Protection bank vault burglar alarm was originally housed within a vault that it protected.The pair of timers were hand wound and two triple throw knife switches engage the two timers before the bank closed in the evening and would turn the alarm system on when the bank closed and 5 minutes before the bank opened in the morning it would time out which usually ran from 5:05 pm till 7:55 am the next morning. If the bank was entered or the vault was disturbed anytime during the night the system would sound three alarm bells. Two that were above and on either side of the vault door and one larger bell enclosed within a tamper and weather proof housing on the exterior wall of the building. The alarm bells would sound and continue until the vault was opened and the system reset by the manager. It was manufactured by its parent company which was the O.B. McClintock Co. of Minneapolis, Minnesota.

Below are photos of a typical bank alarm control system by the American Bank Protection Co., the leading maker, c. 1903 using a pair of Seth Thomas no. 10 dual spring clock movements for the timers. I could not find any photos of alarm control panels that used the earlier timer designs employing standard time lock movements but these would have been used in the same way as those shown.


American Bank Protection Co. central control panel. The one on the left is an earlier model with the lower section containing the dry cell battery case clearly illustrated below. The same area on the photo to the right also contains the battery electrical supply. These were needed since central electricity stations were not yet common, especially in rural areas. Both show the use of a pair of timers which provided redundancy in the case of the failure of one; the same design used in multiple movements found in time locks.


These photos show a close up of the upper and lower sections of the control unit with the timer pair clearly visible in the second photo.


The first photo shows a later pair model alarm timer control systems by American Bank protection Co., c. 1920. By this time central station electrical supply was common and the bank alarm only needed a small emergency battery supply located in the small square box in the lower right in the event of an interruption of the electrical supply; it was also connected by telephone lines to a central monitoring station. At this point only one alarm timer is used in an effort to economize on design and in recognition of the reliability of the timer. The failure of the timer would cause a false alarm, a far less serious problem than would be caused by the failure of a time lock within a safe resulting in a lockout and expensive drilling of the safe. The second photo is indicative of the American propensity for litigation surrounding this business and is no different from that which pervaded the time lock industry the prior century.

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(1) American Genius Nineteenth Century Bank Locks and Time Locks, David & John Erroll, pg. 327