REVOLUTION_International_Vol 54

A NEW HI-BEAT MOVEMENT
Grand Seiko is one of two watchmakers that have
consistently delivered a high-speed escapement. While
other watchmakers have experimented and developed
movements that deliver regulation rates upwards of 10 Hz,
the Hi-Beat movement has been made regular appearances
in Grand Seiko watches. This year, the brand has introduced
a new Hi-Beat caliber, the 9SA5, in a limited edition Grand
Seiko 60th Anniversary edition, the reference SLGH002.
The 60th Anniversary Limited Edition SLGH002 builds
on the Grand Seiko Style that was defined in 1967, but with
discreet cosmetic updates. For one, the watch sits with a
thickness of just 11.7mm, which make for an elegant profile.
Broad beveled, visibly wider lugs and bezel alternate with
polished and brushed finishes, giving the 40mm yellow gold
case a great sense of presence despite the watch being quite
thin. Matching the more prominent lugs, the elements on
the dial — the hour markers, hands and date window — are
likewise given greater volume so that nothing on the watch
face looks out of place.
Now the reason why the watch is as thin as it is, is
because of that new movement, the caliber 9SA5 Hi-Beat
36000. Grand Seiko says that the new movement is 15
percent slimmer than other Hi-Beat calibers that are
presently in production. This was made possible by a new
approach to their gear train layout, which has all of the
components laid out on a
single horizontal plane. Its
barrels are in series followed
by the wheels, again in series,
and finally the escapement assembly.
From barrel to escapement, every component
relates to one another in series.
The next innovation in the movement comes courtesy
of a brand-new escapement design. The new mechanism
allows for the escapement wheel to directly transmit power
to the balance wheel. But there is still a traditional pallet and
fork assembly. So what happens is that when the escapement
wheel spins in one direction, it hits the balance wheel
directly and when it spins in the opposite direction it gives
impulse to the pallet fork.
The last bit of innovation that must be mentioned is
a new free-sprung balance developed for this caliber.
Preceding Hi-Beat movements used flat hairsprings while
the 9SA5’s hairspring includes an overcoil, the shape of
which was engineered after having put the initial prototypes
through 80,000 simulations.
The Grand Seiko
60th Anniversary
Edition SLGH002
with Hi-Beat
movement.
Above right
The 9SA5 caliber
features a new gear
trainlayoutwithall
of its components
on a single plane,
thus slimming the
movement down
significantly. It also
features a direct
impulse escapement
and new freesprung
balance.
BACK TO THE FUTURE 103