Chrono IV

The column wheel is the correct way to build a chronograph. It is also the more expensive way. A cam-operated chronograph uses a simpler mechanism that can be produced more quickly. The Chrono IV uses a column wheel.

The Column Wheel

The column wheel has eight columns arranged in a circle. Each push of the start/stop pusher advances the wheel by one column. The columns sequentially engage and disengage the clutch, the brake, and the reset function in a choreography that happens in approximately 6 milliseconds.

Through the sapphire caseback, the column wheel is visible in the lower left of the movement, rotating by one eighth of a turn with each push. It is satisfying in the way that precise mechanical things are satisfying.

The Vertical Clutch

Most chronographs use a lateral clutch: the chronograph wheel slides sideways to engage the timekeeping train. This introduces a small jolt at start that can displace the seconds hand by one or two tenths of a second.

The vertical clutch in the Chrono IV engages from below. The chronograph wheel descends to meet the timekeeping wheel. There is no jolt. The hand begins from zero with no displacement.

The Pulsometer

The pulsometer scale on the chapter ring is calibrated for 30 pulse beats. Time 30 beats, stop the chronograph, read the number where the seconds hand points. This is the heart rate in beats per minute, without calculation. The scale was designed in collaboration with cardiologists at the University of Berne. It is accurate.

The Pushers

The pushers on the Chrono IV are machined from the same bar stock as the case. They engage with 800 grams of resistance and release cleanly. There is no play, no rebound, no creep. If you have used a chronograph with inferior pushers, you will notice the difference immediately.