Chronograph Watch Product

Overview

A chronograph watch is a mechanical wristwatch with an independent stopwatch function built into the movement. The timekeeping side runs continuously; the chronograph side sits idle until a pusher couples it to the running train, at which point a central sweep hand and one or more register hands begin counting elapsed time. Pressing the same pusher again freezes the reading, and a second pusher snaps everything back to zero.

The watch divides into the Base Movement, which keeps time; the Chronograph Module, which measures intervals; the Winding & Setting System, which keeps the mainspring charged; and the Dial & Hands, Case, and Bracelet that display, protect, and carry the whole mechanism.

How it works

Energy comes from the Mainspring Barrel, a toothed drum containing a coiled alloy spring good for roughly 50 hours of running. The barrel turns the Going Train Wheels, which gear its slow, hard rotation up to the fast, light rotation needed at the escapement. The Escape Wheel is released one tooth at a time by the Pallet Fork, and each release delivers a small push to the Balance Wheel. The balance, returned through every swing by its Hairspring, oscillates at 28,800 vibrations per hour, so each escape-wheel tooth corresponds to exactly 1/8 of a second. All fast-moving pivots run in the synthetic rubies of the Jewel Set, which hold friction low and stable for years between services.

The chronograph layer is controlled by the Column Wheel, a small castellated ratchet. Each press of the top Chronograph Pusher rocks an Operating Lever that advances the column wheel by one tooth; the levers riding on its columns then either drop into the gaps (engaging the chronograph) or are lifted onto the columns (disengaging it). This gives the pushers their characteristic crisp, sequenced feel: the same button always means start or stop depending on where the column wheel sits.

Coupling is done by the Vertical Clutch. Instead of meshing two gears edge-on, which makes the sweep hand jump at start, the vertical clutch presses a friction surface axially onto a wheel that is always turning with the fourth wheel of the train. When the clutch closes, the Chronograph Runner picks up rotation smoothly and the central Chronograph Seconds Hand begins its sweep. Once per revolution a finger on the runner steps the Minute Counter Wheel forward one tooth, and a slower take-off accumulates onto the Hour Counter Wheel, so the three Subdial Hands read elapsed minutes and hours as well as running seconds.

Reset is mechanical and instantaneous. Each counter wheel carries a heart cam, a spiral-sided steel cam whose lowest point corresponds to the zero position. Pressing the lower pusher releases the Reset Hammer, which slaps all the heart cams simultaneously; each cam rotates under the hammer face until its low point seats, carrying its hand to exactly zero regardless of where it stopped.

Winding and setting

The Winding Rotor, a semicircular weight running on a Ball Bearing, swings with every wrist movement. Its rotation passes through the Reverser Wheels, a pawl-clutch pair that turns motion in either direction into one winding direction at the ratchet wheel, so the mainspring charges no matter how the rotor swings. For manual winding and setting, the Crown drives the Winding Stem into the Keyless Works, which routes crown rotation to the barrel in the pushed-in position, to the Date Disc at the first detent, and to the motion works for hand setting at the second.

Case and externals

The Case Middle is forged 316L stainless steel, bored for the crown tube and the two pusher stems, and sealed throughout by the gaskets of an O-Ring Set. The Sapphire Crystal is synthetic sapphire, hard enough (Mohs 9) that only diamond scratches it in normal use, and the Caseback screws down against its own gasket for 100 m water resistance. The fixed Tachymeter Bezel carries a tachymeter scale: start the chronograph at one kilometre marker and stop at the next, and the sweep hand points to the speed in km/h.

The Bracelet is built from solid machined Bracelet Links, terminated in fitted End Links and retained at the lugs by 1.8 mm Spring Bars. The Folding Clasp folds over itself with a safety latch and provides micro-adjustment for fit.

Service notes

A chronograph carries roughly 100 more components than a plain three-hand movement, and the chronograph works run dry of optimal lubrication on the same schedule as the base calibre. Typical service intervals are five to seven years, at which point the movement is stripped, the Jewel Set pivots re-oiled, the Vertical Clutch inspected for friction-surface wear, and the case gaskets replaced and pressure-tested. Running the chronograph continuously is harmless with a vertical clutch; with older lateral-clutch designs it measurably increases amplitude loss.