| TOUR
OF SINCLAIR HARDING'S H1
Winding >
Power >
No Friction
> Wheels
n' pinions > Grasshopper
> Pendulum
> Grid
Iron > Balance
Springs > Time |
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Winding the Clock
The Sinclair Harding H1, unlike the original, is designed
to be a practical piece and needs to be wound every 7
days, it will in fact go for nearly 8. A substantial cranked
key winds the Fusee through a 2:1 step down gear ratio
making the once a week experience almost effortless.
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Power
The power to drive the H1 is provided by 2 springs housed
in barrels. The right hand larger barrel shown in the
opposite picture, around which the cable is wound is
empty and the spring is actually housed in the left
hand smaller barrel. The cable drives a 2 start Fusee,
carefully matched to the two springs and in order to
ensure the escapement continues to operate while winding,
maintaining power is provided to the Fusee Assembly.
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No Friction!
John Harrison was very clever and wanted to avoid using
lubrication wherever possible. The arbors around which
the springs are wound are mounted on rollers. On the
Sinclair Harding H1, these rollers are positioned on
the outside of the plates and if viewed carefully and
be seen rotating very slowly.
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Wheels N' Pinions
Harrison used wooden wheels and pinions throughout,
using the Lignum Vitii, a wood which exudes its own
oils. On the Sinclair Harding model, the wheels and
pinions were purposely made in brass and polished steel.
The interaction provide a fascinating spectacle and
reflections from the plates and highly polished wheels
serve only to deceive the observer.
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Grasshopper
At the top of the train and on view from the front is
John Harrison's famous Grasshopper Escapement. Designed
to have no sliding surfaces (and hence no lubricant)
watch how the escape wheel impulses the pallets which
then gently let go the wheel when the opposite pallet
engages.
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Pendulums
Distinctive in their shape and linked together,
the Sinclair Harding Pendulums are made of Invar - a
material with a low Coefficient of Thermal expansion
and not available in Harrison's day - what luxury!.
The Pendulums arbors are mounted at each end on what
are small segments of very large rollers, which form
a small Vee. This arrangement needs no lubrication and
results in minimal friction.
The length of each rod, combined with
the massive Bobs and the balance springs ensure that
the whole assembly oscillates every 2 seconds. The counterpoised
oscillation ensures that the rolling motion of a ship
would have equal and opposite effects on each pendulum
with a nett effect of - zero. > Below you can see
the links between the two pendulum assemblies
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Grid Iron
On H1, Harrison used a complicated Grid Iron
system, which constantly adjusts the length of the springs
as the temperature varies.
The three gridirons are fixed to the
central plate, the central gridiron shortens as the
temperature increases and the bottom and top gridirons
lengthen. The assemblies are linked together by a complex
toggle and the lever system, which effectively magnifies
the individual movements of each gridiron.
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Balance Springs
The 4 matched balance springs are connected
to the Pendulum rod frame and to a central column mounted
to the back plate. The springs are made from high-grade
spring steel, formed into shape and heat-treated to
maintain the springs shape. The 4 springs have to be
matched to ensure the pendulum system performs perfectly.
To the left shows the top central plunger, which moves
forwards and backwards as the temperature varies which
in turn, adjusts two pads, against which the balance
spring acts.
One can only admire the genius of John Harrison, however
it is hardly surprising that after Sea trials Harrison
found that the system was not responsive enough and
H2 he designed a device, which we now know as the Bi-metal
Strip.
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And now to tell the Time.
The chapter rings are as near to the original
we could get. Made in brass then hand engraved,
wax filled, grained, silvered and finally lacquered
to prevent tarnishing. The dial requires careful study.
The top seconds hand is connected directly to the Escape
wheel, watch carefully as it moves each second, gently
recoiling to allow release of the escapement pallets.
Each revolution is equal to 2 minutes. The minute hand
and Hour hand dials are equal to 2 Hours and 24 hours
per revolution and finally – just in case you
have been at Sea for many days, a calendar wheel indexing
each ½ day.
We hope you have enjoyed looking at
the detail of our H1, we specialise in producing clocks
finished to the highest standard and with a great attention
to detail. Almost every part is made in our workshop
and almost every non-moving part is Gold plated to ensure
the glittering spectacle remains indefinitely.
The first piece was mounted on a Granite
base, which can be gently rotated, and the whole is
protected by an impressive brass framed glass shade.
We like to encourage input into the
design and so the base and style of case are yours to
decide upon.
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