The type GR(C) only changed subtly over the years. Have you seen such an installation? the GRC parts-shifting game I refuse to believe such buildings did not ever exist, and would love to know how it was accomplished. (Traditionally, an 18-inch dial is the smallest that requires a no.2 movement.) The existence of dials larger than 16-inch or any outdoor dials has not been confirmed in buildings originally fitted with a GRC system. Normal FMT cases were also used in double-sided brackets.Īs far as I know, the GRC movement was only ever made in the no.1 size. There are two sizes of backbox: the smaller FMT-10 (and all Johnson FMT) size, and the taller FMT-12/16 size. The original aluminum brackets have a certain iconic look by themselves, in my opinion. The FMT case requires a special backbox (a type of conduit junction box) with specifically-spaced hanging brackets (examples of which are shown on the SET FMT backboxes and accessories page). Shown below is a size comparison of FMT cases of circa-1960 design (random selection) fitted with GRC movements.Ĭomparison of FMT-16, FMT-12, and FMT-10 (from rear, showing relative size of movement) Stand-alone synchronous movements were also offered in these cases. These are the only types of no.1 secondary movements known to have been mass-produced by the original Standard Electric Time Company in the postwar period. The following seven types of secondary movements were commonly available in the modular FMT/RMT cases at certain times: AR3 (original AR type), AR2 and AR2A, and GR and GRC (120v and 24vac). FMT-12 is the most common case, certainly and RMT-SQ-10 is the most rare case, in my opinion.) (I have not seen the square version made before late-1950s, or an art-deco dial or stepped hands in 16-inch size. The FMT (flush-mount) and RMT (surface-mount rim-mount) cases came in 10-, 12-, and 16-inch round models, and 10- and 12-inch square models. Starting in the postwar period, all SET movements in no.1 size were commonly mounted in the FMT/RMT modular metal cases. I am also interested in any other paperwork regarding GRC systems. I would really like to have a copy of a manual similar to the first one, only from about 1958~60 (showing the secondary movement with Ingraham Z drive motors and 12-hour correction). ( note: right-click, Save As… to download files directly) » SET 108-448 GRC secondary drive motor conversion kit instructions, April 1968 Most of the information presented here focuses on the 120v version. However, higher voltage doesn’t lose as much over long wire runs (in larger, sprawling buildings). The extra expense of the transformer could make a low-voltage system less cost-effective for small installations. A 24vac system can be installed using class-2 low-voltage wire, and so does not require conduit to meet code for commercial buildings (the wire can be run in the same raceway as communications cable, such as for a telephone or PA system, which reduces installation costs). GRC movements were available with either 120vac (US mains voltage often equivalently stated as 117v, 115v, and/or 110v) or 24vac motors.

They were also stamped “Flexchron” during the 1960s, which is certainly a marketing-friendly term.

The dual-motored synchronous design and the fact that most were mounted in FMT (flush-mount) cases accounts for most of the weird names. One rarely sees these things described by their proper name, however, and there are almost as many different names for them as there are ways the movements find to not work quite right. Only one type of clock system with synchronous secondary movements was ever mass-produced by the Standard Electric Time Company of Springfield, Massachusetts: the “GRC” (originally “GR” I tend to use GRC as an umbrella term), the dual-motor design with the odd rounded-square movement. GRC movement (from rear Ingraham Z drive motor, Synchron 640 reset motor, optional CA-1 buzzer)

Lathem time clock buzzer