The Glashütte Original Senator Chronometer Tourbillon, launched in 2019, is one of the most remarkable tourbillons in watchmaking, as it combines a zero-reset function and a hacking seconds in a tourbillon watch with unusual sophistication. While a hacking seconds function might seem essential in any watch that aspires to accuracy, much more in a tourbillon, it remains uncommon, and rarer still when paired with a zero-reset. Moreover, the Senator Chronometer Tourbillon is the only one where the entire flying tourbillon with the seconds hand attached can be reset to zero.

Zero-reset is typically implemented with a heart cam rigidly fixed to the arbor that carries the seconds hand. When the crown is pulled, a brake stops the balance and a lever presses against the heart cam, like in a chronograph, forcing the hand precisely back to zero. In this case, the tourbillon cage merely halts but does not rotate with the hand.

Glashütte Original Senator Chronometer Tourbillon (©Revolution)

However, there are several unusual features in the Senator Chronometer Tourbillon. The fourth wheel is not permanently fixed. In normal running, it is locked in place by a holding lever, so the cage revolves around it exactly as in a classical tourbillon. Co-axial with the cages it’s a zero-resetting module, a ring assembly made up of a carrier ring with inward-tipping pawls and an inner planet ring. This module runs on bearing rollers around the tourbillon aperture and is held axially by a stop ring.

When the crown is pulled to the second position, a cam-controlled train of levers acts on the zero-resetting module. The stop ring is lifted by a pair of external stop pawls; its inner ramp drives the internal pawls inward, and those pawls cam a brake ring that slides upward on the tourbillon hub. The brake ring pushes a transfer pin that flexes a cage-mounted brake spring against the balance rim, cleanly halting oscillation.

Glashütte Original Senator Chronometer Tourbillon (©Revolution)

Then, when the crown is pulled to the third position, the cage advances clockwise to zero. A detent pawl swings in to define the zero stop, the holding lever releases the fourth wheel from the plate, and the zero-setting module is freed from the plate so it can rotate with the cage. With the going train still running, the coupled assembly—cage, seconds hand, fourth wheel and zero-setting module — advances under barrel torque until the cage stop meets its counter-stop, placing the seconds hand exactly at zero. A rotational damper located to the left of the tourbillon aperture moderates acceleration, ensuring smooth, controlled motion of the carriage.

Glashütte Original Senator Chronometer Tourbillon (©Revolution)

More than that, as the tourbillon returns to zero, the minute hand advances by one minute so both indications are synchronized. Turning the crown then indexes the minute hand in discrete one-minute steps. Inside, the minute train is fitted with a 60-position detent. It is a ring of minute notches that is advanced by a spring-loaded pawl. This eliminates ambiguity; the minute hand can’t hover between markers and it allows for proper synchronization. When the balance is released, the seconds start from zero and minutes from a true index.

The result is a display that sets as precisely as it runs. It is a highly elaborate mechanism but fitting, and the watch is chronometer-certified—a distinction still exceptionally rare among tourbillons.

Glashütte Original Senator Chronometer Tourbillon (©Revolution)

Tech Specs: Glashütte Original Senator Chronometer Tourbillon

Movement Manual winding Caliber 58-05; 70-hour power reserve
Functions Hours and minutes; seconds on flying tourbillon; stop-seconds mechanism; zero reset; minute detent
Case 42mm × 12mm; platinum; water resistant to 50m
Dial Blue with off-centered time display
Strap Blue Louisiana alligator leather