American Bank Protection Co., Minneapolis, Minnesota, pre and post 1902 models.
American Bank protection Co. was a major alarm system maker at the end of the nineteenth century. American Bank Protection was a subsidiary of O. B. McClintock, a company that also made burglar alarm systems under their own name, although not the alarm timers, as well as industrial master clocks, street clocks, and indoor public clocks. The American Bank Protection Co. produced two types of alarm timers. The earlier model was designed around a the standard seventy-two hour E. Howard L-size movement that was then in use in Yale's time locks and as seen in Bankers Electric alarm timers. However with the takeover of Howard by the Keystone watch Case Co., L-movement production came to a total halt in 1902., forcing American Bank protection to go elsewhere for timer movements.
One of American Bank Protection's design innovations was a new actuator shape. Based on the same single seventy-two hour E. Howard movement as the Bankers Electric model with a pin that slowly turned with the dial (visible at the dial bottom), the American Bank protection design had an armature arm with a curved extension that rode up on the pin, lifting the arm and disarming the alarm. (1)
The alarm timers made by the American Bank Protection Co. post 1902 were quite different in appearance from those of Bankers Electric. The bankers Electric models were designed after the time locks they grew from, but the American Bank timers used spacious wooded cases with their own internal wiring. Rather than relying on the alarm box for insulation, the American Bank Protection is itself made of insulating materials, mostly wood. and features the electric contacts on the top, ready for connection to the alarm system.
Most companies including those making time locks affected by E. Howard's exit from the movement market turned to Seth Thomas, and American Bank protection was no exception. The company's post-1902 alarm timers employed a single-escapement Seth Thomas #10 double mainspring movement with a twenty four hour dial. A clock speed adjustment is visible at the top of the dial. Notably, the electric mechanism of this later American Bank protection timer is based closely on an earlier design originally patented by Edwin Holms in 1867 and reissued in 1880, see below. Rather than suggesting a connection between Holms and American Bank Protection, this similarity was more likely due to the recent expiration of the seventeen-year patent protection on Holm's design. This style of timer was typically mounted in pairs in an elaborate wooden control panel, which also housed the direct current batteries that powered the alarm system. (1) See introduction page.
The ST #10 double mainspring movement is very common. Note that the double spring barrels drive through a common central pinion. It found service in heavy round brass cases for boiler room clocks and anywhere a reliable timepiece was needed....a heavy duty work-horse movement. However its main service was in timing and recording apparatus where a powerful center (minutes) shaft was used to turn a paper chart or open/close electrical contact switches (as in this case). Most have simple alarm-clock like balance wheel pivots and a rugged lever escapement. Unlike the movements high quality movements found in time locks where failure could be catastrophic, movement failure here would simply allow the alarm to stay armed past the time of the bank's opening.
c. 1910. This model contains a rare seven-day timer option similar in function to the 'Sunday Dial' featured on the Yale Model #1 time lock where the timer can skip weekends automatically. The mechanism is a seven armed star wheel, each arm having the day of the week and can be seen just inside the inner dial rim at the 2'oclock position. This example is the only one the writer has seen so far with this option. Case 8"h x 8"w x 4"d. file 236
Patents filed October 4, 1904 showing the design for the alarm timer and the associated electrical system.
Holms patent upon which the American Bank Protection Co. timer contact switch was based.