MONTGOMERY "master clock" from a school bell system

Here's another from my 'weird clock' collection that I've been meaning to show off for awhile now... :-)

Made by the MONTGOMERY MFG. CO. INC. of Indiana, this nifty little boxful of clickie-clackies is the "master clock" which once controlled the classroom bell system in a small school someplace. Scored from the state-surplus warehouse years ago for cheap, it measures about 8" x 11" x 5" in its painted metal box with hinged front cover and glass over the clock face itself. All the little brass colored 'tabs' around the outer edge of its dial (which rotates slowly behind the fixed face, along with its minutes hand in front) trigger the little mechanisms immediately under the dial that in turn would be somehow hooked up to the individual bells in each classroom, making them all periodically ring together. (and thus causing all the students to scatter, etc. etc. yada yada)

It in reality runs nearly silently and still keeps good time, only offering the occasional soft "click" or "clack" as the little timing tabs pass by. (which, if one looks closely, only happens during daytime 'school hours' when I'm not often around to even hear it...?) <groan> I don't know how old it really is, but would suspect it dates from the 1970's or so...??