Yale & Towne Manufacturing Co., Stamford, Connecticut - 4 movements, Quad-M, and with 'L' sized movements modification
A. Quad M, c. late 1920's. By this time the 'M' sized movements had lost their wave machine pattern on the front plate and the balance wheel and escape wheel cocks were silver plated instead of brass colored although they still retained their embossed patterns. The third and fourth photos show the original and modified versions of the Quad M side-by-side. 9 1/4"w x 5 1/2"h x 3 1/4"d. Case #392, consecutive movements #5562, #5563, #5564, #5565.
B. Quad-M, c. 1920, modification c. 1950. This example is a retro fit which has had the original, larger Seth Thomas 'M' sized movements replaced by later Swiss made and smaller 'L' sized movements. In this lock no bolt dog is present, it used a side extension to hook into the bolt work thus there is no dog within the case to block the bolt work. This design was also used in Sargent & Greenleaf's Model P but as far as this author knows has not been employed in any other time lock made by Yale. Yet the outlines for the movement beds exactly match those for Yale 'M' movements in the time lock so one must assume this was originally a Yale time lock. One can see the changes needed in the key eyelets on the door to accommodate the smaller movements with the metal overlay in the first photo and fourth photo, as well as the the smaller spring barrels compared to the originals in the 5th photo. The smaller movement was fitted to a base plate that matched the original lager movement bed in the time lock as shown in the last photo as well as a secondary snubber bar stop.
Retro fits are rare since these were expensive and very few people were equipped or trusted to do this kind of work. Moreover banker's were reluctant to have this done since if the lock did not function correctly, the vault door could not be opened. Probably these conversions, if known to the bank's insurance company, would have had to have been done by a sanctioned firm in order to retain coverage. Retro fits were only undertaken when the movements that belonged in a particular model of time lock were no longer available and it was impractical to replace the the time lock with another model due to the configuration of the vault door's bolt work. All of the other retro fits I have seen are associated with early Sargent & Greenleaf time locks page one, page two; many of those performed by Andy Kotas. Those early time locks used proprietary movements made in house and as time went on those movements were no longer available. I have never seen a retro fit that was designed to replace the later designs that employed modular, interchangeable movements as used in this and all later time locks. It is true that the largest Yale time locks were always fairly rare and perhaps the availability of the 'M' movements became to difficult to maintain the lock and given the unusual bolt configuration of this lock, the retro fit became a necessity. 9 1/4"w x 5 1/2"h x 3 1/4"d. Case #427, movement #79273, 79280, 79281, 79282. file 164
(1)American Genius Nineteenth Century Bank Locks and Time Locks, David Erroll & John Erroll, pg. 294, (2) pg. 295