MALTESE CROSS

The Maltese cross is a wheel shaped like a cross with concave arms, used in watchmaking as a Stopwork device: it blocks a function of the Movement once a defined threshold is reached, in order to prevent any damage related to continuing this function beyond that point. Its most widespread application, on pocket watches from the 18th to the 20th century, concerns the Winding of the Barrel: it prevents the mainspring from being wound beyond its resistance limit.

Each winding Lathe corresponds to a branch of the cross; their number — generally four, sometimes five, six or seven — determines the number of Lathes allowed. The last branch, wider than the others, cannot engage with the Finger drive gear integral with the Train (wheel train) winding: the mechanism then blocks automatically. Beyond seven arms, the cross loses its stopping function and behaves like an ordinary wheel, with a risk of tooth jamming; below four, other technical solutions are generally preferred.

The kinematic principle of the Maltese cross — transforming continuous rotation into intermittent rotation and, in its horological variant, into permanent blocking — is also used, outside the Barrel, for other discrete indexing of the Movement, such as the rotation of satellites or jumping counters.