Chicago Time Lock Co., Chicago, Illinois - 3 movements, Marsh model 1,
The Chicago Time Lock, Marsh Model 1, v.2. The distinguishing features of the
Model 1 v.1 and v.2 are the redesigned movements and the introduction of a
half-glass door in place of full glass.
A side-by-side comparison of the Marsh Model 1. Left a two movement, full glass
door, designed for manual boltwork and equipped with a pair of v.1 movements.
Right, a three movement Model 1, with
half-glass door, v.2, movements and
for use with an automatic bolt motor.
These two photos shows all three of the Marsh style time lock movements. From
left, the Model 1, c. 1903; v.1, middle Model 1 v.2, c. 1904; right Model 2 with v.3 movements,
The three versions of Chicago Time Locks Co's., Marsh movements. From left,
v.1, v.2 in the marsh Model 1 and the movement , v.3 introduced in their Marsh
Model 2, the last design before the take over by Diebold in 1908. The v.3 follows
conventional time lock designs seen in other makers. Chicago also changed
from Seth Thomas to Deuber Watch Co. Notice the change in design on the balance
and escape wheel cocks.
These two photos show the mechanical design changes that took place in the
Chicago time lock movements that distinguish between the Marsh Model 1 v.1,
left, and v.2, right. The v.1 movement has a Geneva stop mounted beneath the
upper subsidiary 5-day dial; the v.2 substitutes a geared wheel in its place.
The hour designations on the dial are reversed between the two because the
design change reversed the rotation of that dial. In addition an idler wheel
meshing between the subsidiary dial wheel and a new pinion mounted underneath
the larger, primary daily winding dial allowing the correct ratio of 1:5 between
the main and subsidiary dials. A third wheel meshes on the same center dial
pinion from below and through cam work mounted below that gear engages the
snubber bar linkage.
The first photo shows the front plate of a v.2 movement. With the primary daily
winding dial removed, (winding arbor where red arrow indicates), one can see in
the first photo the three additional gear wheels. Left, the one under the 5-day
subsidiary dial, next the idler wheel and then the silver wheel controlling the
snubber bar linkage. Both the idler wheel and the silver wheel mesh with the
same pinion located below the daily primary dial and would be mounted over the
winding square arbor. The second photo shows an empty hole indicated by the
yellow arrow. This hole was used in the v.1 design for a screw to secure the
pivot point for snubber bar linkage. That area is depicted by the yellow dot
underneath the idler wheel in the first photo. After the design change was made,
apparently the threaded hole was still made in the plate even after it was made
superfluous. Probably a batch of movements had already been made to the v.1
design and were retrofitted with the additional holes for the new gear wheels
and pinion under the main dial to the v.2 design. The design change happened at
or near movement serial number 100. The v.1 movements are numbered 95 and 96
while the v.2 examples are 104,105 and 117.
These two photos show a v.1 movement. These point out the pivoted snubber bar
linkage. In the first photo the bottom end that attaches to the snubber bar is
next to the red arrow on the left. The arrow on the right points to a stud
mounted to the other end of the lever. That stud engages a detent mounted on the
reverse side of the Geneva stop and is contacted and pushed to its home position
as the subsidiary dial reaches zero. The yellow arrow shows a portion of the
screw head partially obscured by the dial pointer bridge. It is at this point
that the lever pivots.
The next photo shows the same information but at a different angle. The lever
pivot point cannot be seen here. The subsidiary dial turns clockwise as
it runs down to zero. Here it is at zero and the stud on the snubber bar linkage
is pushed all the way home toward the viewer, this causes the other side of the
lever to move in the opposite direction away from the viewer, and is connected
to the snubber bar. In this position the time lock is off guard. The snubber bar
is spring-loaded, so when the operator begins to wind the movement and the stud
is allowed to move as the Geneva stop is turned counterclockwise, the lever is pushed
in the opposite direction setting the lock on guard.
Conclusion: The design change was made because the torque
provided through the Geneva stop detent acting upon the lever stud was
insufficient to ensure a reliable movement of the spring-loaded snubber bar to
the off guard position. Furthermore, the Geneva stop design did not provide an
accurate position for when the lock wound down to zero and the lever was to push
the snubber bar to the off guard position. In the new design, the snubber lever being directly geared to the primary dial attached
to the main spring ensured a positive release.
Around 1903, the Chicago Time Lock Co. debuted the first production time
lock that offered a ninety-six hour power reserve.
Based on a design for
which Ernest Marsh would be awarded a patent,
the earliest style of this time lock had a
nickel plated case housing two or three movements with
both larger twenty four hour primary dial
and a smaller secondary dial above, numbered
with only 0, 24, 48, 72, and 96.
Below is the only other example this author has seen of the Marsh Model
1, v.1, (although there surely are others) and is from
the Mossman Museum, Nicholasville, Kentucky. While
this and the example above are both three movement models, this is designed for
manual bolt work and is equipped with v.1 movements and full glass door.