Sargent & Greenleaf, Rochester, New York - 4 movements, Model M and special order Model M

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   A

A. Model M, (later model #6406). c. 1910-1929. This lock is equipped with the standard drop bolt dog located beneath the movements to operate directly on the vault door's bolt work and is equipped with S&G's largest standard 'M' sized movements. This is a very large time lock and was S&G's largest using their standard 72 hour duration movements. 5 1/2"h x 9 7/8"w x 3 1/8"d. Case #M-157, movements #2041, #2045, #2046, #2047. file 245 

B

Comparison between the standard S&G Model M with 72 hour movements and the special order model M with 96 hour movements. 

S&G 4mvt type N-large (2).JPG (1123789 bytes)  S&G 4mvt type N-large (3).JPG (926616 bytes)  

     

The components of both the 72, (left) and 96 hour, (right) movements are identical. I have examined all of the individual wheels as well as the spring barrel diameters and they are all the same. The planting of the wheel works in the 96 hour movement are spread out a bit more in the vertical direction to take advantage of the taller movement plate. The spring barrel sizes are identical.

The video clip shows a demonstration of the S&G time lock. The drop bolt mechanism was the heart of S&G's design. This was first introduced in 1874 as a round roller bolt, later changed to the 'cello bolt' so called because of its resemblance to the musical instrument and finally the drop bolt as exemplified in this video. However all of these designs worked upon the same simple principal of the drop bolt being released under the influence of gravity. While the first design, the roller bolt was set in a different way, all of these designs worked upon the same simple principal of the bolt being released through the force of gravity. The bolt would be manually set by the operator and would be disengaged through gravity. Many other designs, including the other largest time lock maker, Yale, used springs or the force generated by the time lock movements themselves to move the mechanism that served to block the vault door bolt work. While remote, the possibility of jamming could defeat the time lock. The engineering behind S&G's design was elegant - simple, robust and fool-proof. Qualities that were essential in a bank vault time lock where failure would result in the catastrophic expense of forcing open the door. This example was the largest time lock produced by S&G featuring their long duration timers of 96 hours verses their standard 72 hour models. This time lock would have been installed on the very largest of bank vaults, doors weighing in at 20 to 30 tons or more.                                          

B. Model M, special order, (later model #6406). c. 1927. Lock is equipped with longer duration 96 hour movements. This was the largest time lock made by S&G and had the largest movements, the size 'R'. The time lock case itself has the same width and depth as the Model M with standard 72 hour duration movements, but like the time lock movements, the height of the case is slightly higher. The higher profile of the size 'R' movement plate allowed S&G to move the dial pointer from where it was tucked away on the left hand corner to the center front above the dial. In this author's opinion the difference in the time lock movements size as well as the time lock itself was purely a marketing exercise. The components of both the 72 an 96 hour movements are identical. I have examined all of the individual wheels as well as the spring barrel diameters and they are all the same. The planting of the wheel works in the 96 hour movement are spread out a bit more in the vertical direction to take advantage of the taller movement plate. I have not been able to measure the length and power characteristics of the springs in both types of movements, but I would suspect that here is where there are any differences. It is likely that the 'R' movement has a longer and stronger spring contained within the same sized spring barrel as the 'M' time lock movement. Later on S&G added longer duration locks extending to 120 hours on some of their smallest movements the 'H' series, but this did not involve any changes to the size of the time lock movement. I have not seen this 120 hour duration on any of their other larger movements: the 'L', 'M' or 'R'. It is known however, that the 96 hour option was available on the 'L' time lock movements. Whether this involved a change in the movement's size as was the case with the extended hours from the 'M' to the 'R' series is unknown. 6"h x 9 7/8"w x 3 1/8"d. Case #6406 - 391, movements consecutively numbered, #2209, #2210, #2211, #2212. file 214                                                                           

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