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The Encyclopedia of Horology

Component record · Train

Chronograph Hammer

Partially verified

The lever that strikes the heart cams to reset a chronograph.

What it does

Returns the chronograph hands to zero.

How it works

Released by the column wheel or cam, the hammer falls on the heart-shaped cams and rotates them to a defined zero.

Evolution

Geometry was refined to reset multiple counters simultaneously.

Known variations

  • Single hammer
  • Twin hammer for two counters

Identification for collectors

  • A hand that does not return exactly to zero indicates hammer or cam problems.

Common failure modes

  • Worn hammer faces
  • Weak hammer spring

Related photographs

Large Silver Swiss Centre Seconds Chronograph – 1894
Large Silver Swiss Centre Seconds Chronograph – 1894 — WatchMuseum.org, © WatchMuseum.org, used with permission. WatchMuseum.org catalogue record
Large Silver Swiss Centre Seconds Chronograph – 1894
Large Silver Swiss Centre Seconds Chronograph – 1894 — WatchMuseum.org, © WatchMuseum.org, used with permission. WatchMuseum.org catalogue record
Large Silver Swiss Centre Seconds Chronograph – 1894
Large Silver Swiss Centre Seconds Chronograph – 1894 — WatchMuseum.org, © WatchMuseum.org, used with permission. WatchMuseum.org catalogue record

No confidently matched photograph of this subject has been found yet. These photographs show a closely related record, and are not examples of the type described on this page.

Sources & references

  1. de Carle, D., Practical Watch Repairing
  2. de Carle, D., Watch and Clock Encyclopedia
  3. Daniels, G., Watchmaking

Where sources disagree, the disagreement is stated rather than resolved silently.