WT_2010_01: TEST: TAG HEUER GRAND CARRERA CALIBRE 36 ...

TEST
TAG Heuer Grand Carrera Calibre 36 RS
O
ne look at the dial of the TAG Heuer Grand Carrera Calibre 36
RS Caliper Chronograph and you know right away it is no ordinary
chrono. Introduced in 2008, the Caliper Chrono is the
world’s first automatic chronograph with a rotating caliper
scale (called a vernier scale). The scale, which slides around the
edge of the dial, magnifies 1/10-second measurements by a factor
of 10, making it much easier to read fractions of a second.
Another peculiarity of the watch is that it uses disk displays to
show the elapsed hours at 6 o’clock and elapsed minutes at 3
o’clock. Then there’s the linear small seconds indication at 9
o’clock. And how about that decorated steel bridge sitting
smack dab in the middle of the dial?
It’s the caliper scale that gives the watch its greatest distinction
(and its name). Vernier scales are familiar to most people
from slide rules. They are used to measure fractions of a given
unit. For example: to read 1/10 millimeter, the user checks
which graduation corresponds exactly or most closely with a
millimeter mark. (The last photo of this article provides an example:
the vernier scale begins directly after the 11 millimeter
line, and its “1” index is precisely aligned with a millimeter
mark. The caliper therefore shows 11.1 millimeters.)
TAG Heuer has adapted this device to measure time intervals
instead of lengths. On a wristwatch, the linear track of a
caliper rule is circular so that it can interact with the central
chrono-seconds hand. Here’s how the scale works: After stopping
the chronograph, the wearer uses the red-striped crown at
10 o’clock to turn the caliper scale along the edge of the dial until
the red triangle at the zero point on the scale lines up precisely
with the red tip of the chrono-seconds hand. On the photo on
the previous page, the chrono-seconds hand has stopped between
37 and 38. You use the caliper scale to get the one-tenthof-a-second
measurement. Here’s how: the caliper scale lies
flush with the watch’s 60-minute track. Examine the markers on
the caliper scale to see which marker lines up most exactly with
a marker on the 60-minute scale. In the photo, you can see that
the only marker on the caliper scale that lines up precisely with
a line on the 60-second scale is the 4, indicating 4/10ths of a second.
So the chronograph hand reads 37. 4 seconds.
THE ONLY FREQUENCY that makes measurement of a tenth
of a second possible is five Hertz, or 10 vibrations per second.
TAG Heuer did not have to search very long to find a reliable
movement with this frequency. Its sister brand in the LVMH
Group, Zenith, makes the most famous one, the El Primero
chronograph movement. Its advantages include a powerful eccentric
fine regulator with a long regulator pointer and a Glucydur
balance that is resistant to temperature fluctuations. The El
76 WatchTime February 2010
THE WATCH’S UNUSUAL
FEATURES INCLUDE ITS
VERNIER SCALE, LINEAR
SECONDS DISPLAY AND
ROTATING DISK COUNTERS.