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I have been contacted by a WT owner. Whom has cleverly 3D printed some missing parts.
Of
particular interest is his printing of a bevel gear, crown wheel. Even
down to his use of the correct bronze colour. The bevel gears [or bevel
wheels] sometimes seem to go missing when a WT is removed from an
installation. Spares are rarer than unicorns these
days.
I think I also notice a couple of printed, universal-expansion joints for the lead-off work. Making the drive to large dials possible.
My
contact has kindly forwarded some fine images of his WT. For which I am
very grateful. I have reduced the size of the original images to cater
for those on a slow internet connection. Any reduction in image quality
is entirely my fault.
The overall impression of this WT is that it could have just left the factory. Despite being at least 70 years old. This
WT has been
beautifully restored and finished. Making for a superb, working,
display item. The timber stand is very pleasing and a close match to
originals I have seen online. The diagonal struts are useful in
resisting the power impulse and should extend the period between
mechanical impulses to drive the pendulum.
Certain details point to a later WT movement. It has the pressed steel, contact, steady bars. Rather than the earlier cast brass. Small parts are plated for protection. Rather than the earlier, deep-gold, lacquered brass. The sloping mainframe bar, over the power [pendulum drive] electromagnets, is indicative
of a slightly later model of WT C40A. Probably 1940s-50s?
Interestingly, the coils are silk wrapped wire. Which is the earliest winding arrangement of the huge coils by the Gents factory. Later, the
coils were wrapped individually in a protective bandage. Intermediate
coils were wax dipped to prevent moisture ingress.
This image shows the overall view from the rear of the WT movement. I used the terms "front" and "rear" because the time setting crank and dial were at the front. Not all WT movements were placed for easy access from both sides.
This image shows the similarity of the 3D printed, bevel, crown wheel to
an original. One has to stare hard at it to see any difference. A truly
remarkable feat using modern technology. Not to mention considerable
skill and patience.
The bevel gear cluster is driven by the worm wheel shaft via the first,
vertical, bevel wheel. The larger, horizontal, crown wheel drives all
the other wheels. Allowing a drive for the hands of up to three dials. A
fourth dial would require a coupling on the far end of the worm shaft.
Many towers would have a dial on each face. Each placing greater demands
on the WT depending on wind speed and direction. Plus any ice
forming on the very exposed, metal hands. The clock hands would normally be
balanced just behind the dial. Using counterweights, on extended arms,
jutting from the shafts. Ice would add considerably more weight to the hands. Causing
the clock to work harder "uphill" as the hand rise and running ahead on
the descent.
Another view of the bevel wheel cluster. A very satisfying appearance. I
have zero knowledge about the strength of 3D printing materials. The WT
can produce enormous torque when it is demanded. Which is why it is
built to resist all the likely forces applied to the large, exposed,
clock hands. Often on multiple dials over a long, working life and usually
in less than ideal conditions.
Many clock rooms, towers and roofs would suffer from wind blown dust, rain, snow and debris. Particularly if bells were employed behind open louvers. Birds would often carry twigs into buildings for nesting material. Proximity to the sea would carry corrosive salts in the air.
Many WTs would be protected by a simple wooden box placed over the movement. This protection would often be complicated by the lead-off rods. It relied heavily on the clock minder replacing the box after examining the WT movement.
End view of the WT with the original "Pulsynetic" label on the sloping section of the mainframe.
The
compact form of the WT, compared to weight driven clocks, is readily
apparent. Not only that, but no weight shafts would be needed. Nor safe
and easy access required for a clock winder and minder.
This allowed WTs to be placed in very unlikely positions compared with
weight driven clocks. High up on narrow war memorials. In niches on factory
chimneys. Inside illuminated dials on train stations. They were also employed to
slowly drive display mechanisms, museum and exhibition items.
The worm shaft [arbor] rotated at 1 revolution per hour. Clock dials have a 12:1 "motion work" to drive the hour hands. A straight-through shaft would drive the minute hand inside the "hour pipe." The hour hand would be fixed onto the hour pipe.
The view from the opposite end. Where the terminal block is fixed. This has separate screw terminals for power and for timing pulses. The timing pulses arrive at 30 second intervals from a master clock in a series circuit including dials. The short pulse in the series circuit releases the temporarily locked "waiting train" mechanism.
A small electromagnet is energized by the electrical pulse. Which releases an arm which was holding back the WT's drive to the clock hand[s]. The pause is usually so short [2 seconds] that the effect on the clock dial is never noticed. The drive to the clock hands is otherwise continuous.
The huge, drive electromagnets require 20Volts DC and at least 0.5A. The pendulum uses a Hipp Toggle and V-block to call on a drive impulse if the swing [arc] drops below certain level. The impulse can be repeated as often as necessary to maintain the swing. Providing up to 30 times the power of the occasional impulse!
Note the small hand crank jutting from the front of the WT movement.
This was used to set the WT's dial[s] to time.
Here the view is from the front of the movement showing the bevel wheel cluster seen through an aperture in the WT frame.
The Hipp toggle and damper lies just below. The damper prevents the Hipp toggle from catching in the V-block on the return journey of the pendulum. A stub of rubber hose on the tip of the arm silences any rattle.
The original, time setting dial is present on the face of a bevel wheel. The hand crank would be turned on the WT worm shaft [arbor] to move the hands on the dials forwards. A pointer of bent brass sheet is usually present to indicate the time.
The time setting dial having quarter hour markers. A valuable asset before the mobile phone could be used to tell the clock adjuster the time showing on the external dial[s.] A regular difficulty arising when the annual Spring and Autumn time adjustments take place for Summer and Winter Time. Also known as "Daylight Saving Time."
A close-up of the lead off work on the end of the worm wheel shaft.
[arbor in horological terms] This link would often provide the drive to a single dial. Or a further dials if a bevel gear cluster was present. The printed expansion link is in the
foreground. Yet to be trimmed to two bars to fit into the forked element just beyond.
This clever arrangement has been used for centuries in turret clock, lead-off work. The drive rods to the hands of distant dials, would expand and contract in roof spaces and towers with changing temperature. Soaring in summer and freezing in winter. The change in rod length could be accommodated by the slots ion the drive links.
Old buildings would settle and move over time. Requiring a degree of flexibility in the lead-off work. These reliable, low friction, bar and fork links provided the vital freedom in the [often] very long drive rods. The earlier links would probably be hand forged by a smith in red hot iron.
The further advantage of a fork and bar, drive link was the inability of the drive rods to turn backwards. So that the time would not be lost due to any imbalance in the system. [Ice or wind on the hands] Nor vary much between widely separated dials on different parts of a building. Few architects would have the necessary funds to provide a separate WT for each dial on a building. Multiple WTs were usually reserved for the very largest dials in history. On prestige building projects at the beginning of the 20th Century. The Liver Building in Liverpool being an excellent example.
One weakness in the drive rod [lead off] system was corrosion in the plain bearings required to keep the rods on line. Weight driven, turret clocks usually had a much smaller safety margin against friction or wind pressure on the hands. The clock would stop. While the WT was uniquely powerful thanks to the automatically demanded multiples of drive impulses to the pendulum. All thanks to the genius of the Hipp Toggle system.
This might cause problems. If the power demand was simply to overcome friction in the lead-off work. Possibly even causing damage. Clambering about in a vast, draughty and unlit roof or tower. To check for bearing tightness in the lead-off work, can't have been an easy task. The WT would carry on regardless until something finally broke. This might explain the loss of bevel wheels. If the [bevel gear] teeth were the weakest point in the whole system.
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