Marine Chronometer Mechanism Adapted for a Wristwatch

This "Constant Force Tourbillon" simultaneously incorporates a "constant force mechanism" that maintains a steady power supply to the watch and a "tourbillon" that ensures accuracy through rotation.Arnold & SonIt is a complex timepiece unique to the brand. The dial is open-worked, revealing the watch's mechanism divided into four sections.

The upper right and upper left sections house the mainspring barrels, which serve as the power source. Power is transmitted from here to the constant force mechanism in the lower left. This mechanism contains a spring that stores power, which is released one second after being wound. The energy released then transfers to the tourbillon mechanism in the lower right, causing the carriage to rotate and the escapement to regulate the watch's movement.

By temporarily storing the power of the hairspring, a constant force is delivered to the tourbillon mechanism even when the main power source weakens, ensuring consistent accuracy until the mainspring is fully unwound. This is a system adopted in the marine chronometers of the founder's era, and its reproduction in a wristwatch is truly commendable.

ARNOLD & SON

Forging a Unique World with Original Complications (2)

The Second Hand Jumps Every Second

In mechanical watches, the second hand moves in very small increments, less than a second at a time, making it appear to move continuously to the human eye. This is called "sweep second" motion. In contrast, like the wall clocks found in train stations, the second hand ticks at precise one-second intervals. This is known as "step second" motion.

Achieving step second motion in a mechanical watch requires a special mechanism. This watch is a tourbillon equipped with such a mechanism, called "True Beat," and the "TBTE" in its model name is an abbreviation for "True Beat Tourbillon Escapement."

The mechanism that drives the second hand in step motion is located on the back of the watch. Viewed through the exhibition case back, an anchor, similar to that of an escapement, engages with the gear beneath the second hand. This anchor moves back and forth, engaging and disengaging the teeth of the gear coaxial with the second hand every second. In conjunction with this, the second hand moves, ticking off each second.

This mechanism was incorporated by John Arnold into his marine chronometers, lending a sense of historical weight. Through the open dial, one can admire the movements of the mainspring barrel, the second hand mechanism, and the tourbillon carriage on their wrist. A closer look at the gear teeth reveals the use of wolf's teeth – shaped like a wolf's canine teeth – for efficient power transmission, showcasing originality down to the finest details. This is a recommended piece for connoisseurs seeking something beyond a standard tourbillon.

Time Displayed by Numbers Moving Across a Fan-Shaped Plate

This is a unique timepiece that displays the time using three transparent rotating discs. At the center of the dial is an impressive gold gear, the inspiration for the model's name, upon which three rotating discs are mounted.

These transparent discs are marked with numerals. When a disc moves over the white fan-shaped plate, located from 10 o'clock to 2 o'clock, the numeral appears, indicating the hour. The numeral travels across the white plate from one end to the other over the course of an hour, while a 60-minute scale is printed alongside, allowing the minutes to be read.

Once a numeral reaches the end of the plate at the 2 o'clock position, the numeral on the next disc moves onto the plate to display the subsequent hour. The original concept for this idea comes from a table clock made in 17th-century England. This creative reinterpretation of historical mechanisms has led to further evolved complications.

BULOVA JAPAN
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