Hall's Safe & Lock Co, Cincinnati, Ohio - 1
mvt. w/ Chronometric Time Attachment
Repairs to the movement
When this time lock came to me it was not in working condition. There were
several problems with the lock
The first issue was that the main wheel, the spring barrel wheel, was
frozen. When one put a winding key on the square it would not move. At first
it appeared that the ratchet may have been made immovable for some reason.
It was impossible to try to dislodge it away from the teeth of the ratchet
wheel. This lock was never equipped with maintaining power, so the secondary
ratchet used in that system did not exist. The problem here was that given
the fact the ratchet could not be dislodged, and the ratchet wheel was
frozen solid to the main wheel, there was no conventional way to let down
the main spring, which was also wound nearly all the way around.
The first photo shows a close up of the escapement enclosure, circled area.
The red arrow shows a temporary wire wrapped around the wheel work to hold
the mechanism in check. Next I had to carefully loosen the two screws that
held the escapement enclosure to the top plate resulting in the gap between
the enclosure and the movement top plate. This allowed the fifth wheel, red
arrow second photo, in the movement train to be disengaged from the
escapement wheel within the enclosure. After removing the restraining wire,
the movement could then be allowed to slowly spin down until the spring was
fully released. This is not the recommended way of letting down a movement
as damage to the delicate sixth escapement wheel is very real, but it was
the only way given the incapacitated main ratchet assembly. Had this
movement been made in a more conventional figuration with the the escapement
on the same plate as the rest of the wheels and mor importantly not been
within an inaccessible enclosure, this process would have been made far
These first photo shows the top plate removed from the wheel works. Next the
remaining wheels and other assemblies mounted to the bottom structure. The
design of this movement varies from a conventional time lock. In the first
photo one can see the entire escapement containing the balance wheel,
escapement and escape wheel covered by the enclosure. Normally these
components are secured with narrow bridges allowing one to readily see these
components. Instead only two small observation holes are provided to let one
see these components. In reality it is nearly impossible to properly observe anything.
The other unconventional design is the fact that the escapement is not
mounted on the same plate as the rest of the wheel train complicating
reassembly. The implication of these two features made the repairs
needed much more difficult.
The ratchet is seen under a 30x glass as a simple triangular piece spring
loaded from beneath the ratchet wheel. It differs from a conventional design
in that it lacks a separate ratchet click and spring. If it had this
arrangement it would have been possible to push the ratchet click out of the way
of the teeth. But here the small triangular piece is firmly wedged between
the teeth. The conventional design would have required the ratchet wheel
teeth to be above the surface of the brass decorated rim for the ratchet
teeth to engage on the ratchet click mounted to the rim's surface. However, there
is more than enough clearance for this so it is a mystery why this inferior
design was chosen. I have not seen this method used on any other time lock,
probably for good reason. The second photo shows the massive main spring,
the barrel cavity is 2" in diameter. The full 48 hour duration of the lock
requires one turn with setup of the spring being another turn. So it is
curious why the need for the huge spring where the majority of its coil is
After the ratchet wheel and main barrel wheel were disassembled it became
apparent what the problem was. The ratchet itself was not the the cause of
the frozen main wheel, but the green sludge that was certainly at one time
the grease used to lubricate between the silver ratchet wheel and the face
of the main wheel. It had over the past hundred years dried out to become a
solid glue between these two parts. Failed lubrication is the primary reason
why clock and watch movement have problems. The lubrication either dries out
increasing friction or attracts dirt turning it into a grinding paste
destroying the steel pivots of the wheel train. Abraham-Louis Breguet one of
the most famous and respected watchmakers was reputed to have said "Give me
the perfect oil and I will give you the perfect watch". It was as true in
the later 1700's as it is today. The second photo shows the 108 parts that
comprise the time lock.
One of the escapement jewel pallets was loose and had to be re-secured to
the escapement. This was a rather simple and straightforward repair since it
was secured fully flush into the jewel box of the escapement.
The other jewel pallet was positioned in a most curious and precarious way.
One can see it being slid halfway out of its box with the gap illustrated by
the black indicator in the first photo. The reason for this arrangement
becomes obvious in the second photo. Here the balance wheel, escapement and
escape wheel of the lever escapement are shown. The pivot points for each
are illustrated by the red dots between the two upper and lower white lines.
A conventional lever escapement is a simple straight line as demonstrated in
the line represented by (1) in the photo. This is the
simplest, most common and efficient design and is used in just about any
other time lock (and watch using this type of escapement) I have seen.
However, in this example the geometry has been altered to introduce an angle
as illustrated in (2), and following the actual pivot
points of the three escapement components. This was done because all of the
wheels in the train, excepting the central barrel wheel, run along the arc
of the upper circumference of the open dial cutout. Since this was a
prototype, the Hall company simply took a conventional escapement part and
pushed the jewel outward to make up for the change in the angle of
engagement with the escape wheel. Normally both jewels would have been
adjusted to perfectly engage the escape wheel and the geometry and
adjustment of these components is devilishly tricky and a specialty within
watch making itself. At the time and even today, the final adjustments made
with the escapement itself is an individual and skilled labor profession.
There is a bit of space within the each pallet jewel box for adjustment.
Here the red jewel is backed completely into the box, as might be expected
with the change in geometry with its counterpart correspondingly being
pulled out of its box. It is a tribute to the jewel setters (and a bit of
luck) that this worked with the altered set of jewel positions used in an
escapement not designed for this geometry. Another indication that this was
a test piece is the fact that the escapement tail where it engages the
impulse jewel of the balance wheel is a soldered-on piece. Apparently the
'off the shelf' escapement, in addition to being designed for a straight
in-line arrangement, was also a bit too long for this application. So
the escapement arm was snipped and the impulse fork soldered on. Again,
under magnification it all looks crude and ad hoc, but one must give credit
to the people who created these one off experimental designs that
ultimately had to be tested within the confines of a safe that required a
100% functionality to prevent a lockout.
The next problem was particularly vexing. The balance wheel roller jewel was
also a bit out of alignment. This part is the smallest piece an any watch
movement. It is also subjected to the highest degree of stress as this is
part is engaging several times a second. Here the jewel is about 1mm long
and about a 50th of a millimeter in diameter. It also has the profile of a cylinder cut longitudinally
in half. The first photo shows the roller jewel, red arrow, in relation to
the balance wheel and sewing needle. Next a closer view through the 30x
The roller jewel is shown secured to the balance wheel. This was a tricky
process. The hole in the balance wheel was very large in relation to the
jewel so precise positioning was required verses the escapement impulse fork in two
dimensions. For this application I chose to use conventional
epoxy since it has a long set up time. I studied carefully the geometry
needed for this part and to be honest, had nothing more than an eyeball
guesstimate to position the jewel. Once the epoxy was partially set I
inserted the jewel and set it to the correct position. Of course the part
sticking out above the glue had to remain absolutely clean or the escapement
would stick. The only redo would be to re-dissolve the glue and start over.
Fortunately the first trial was a success.
The time lock was now back to operational condition.