Chronographs and tachymeters: why the long seconds hand may stand still

Many chronographs reserve the long central seconds hand for elapsed-time measurement and put running seconds on a subdial. A stationary central hand is therefore not necessarily a fault.

Start, stop and reset

A common two-button arrangement uses one button to start and stop and another to reset, but designs vary. Many movements must be stopped before resetting; flyback mechanisms are a different case. Check button functions and any screw-down pusher sleeves before operating.

Read the counters and the scale

Subdials may display elapsed minutes, hours or ordinary running seconds. A tachymeter converts the time needed to cover one chosen distance or quantity into an hourly average rate. It does not automatically measure speed, and the chosen unit must remain consistent.

Consider operating load and water restrictions

Running a chronograph engages additional mechanisms and may affect reserve or behaviour. Whether it should run continuously depends on the design. Pusher operation under water is not automatically permitted by a water-resistance number.

Common misunderstandings

Do not force a running chronograph to reset unless its mechanism explicitly supports that operation. Repeated hard pressing does not repair a misaligned zero and may worsen a mechanical problem. Have unexpected resistance or persistent misalignment assessed.

Your practical checklist

• Distinguish elapsed seconds from running seconds.
• Follow the movement's permitted operating sequence.
• Verify continuous-use and underwater-pusher restrictions.