Sargent & Greenleaf, Rochester, New York -
4 movements, Model M and special order Model M
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
Comparison between the standard S&G Model M with 72 hour
movements and the special order model M with 96 hour movements.
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.