Glossary · Regulation

Drop and lock

Escapement measurements describing free travel before locking and depth of lock on the pallet.

Explanation

Drop and lock are the two escapement clearances. Drop is the free run of an escape-wheel tooth after it leaves one pallet before landing on the other; lock is how far the tooth rests on the pallet's locking face. Correct drop and lock keep the escapement secure without wasting energy. Maladjustment shows as unlocking under shock or as heavy, rate-killing lock.

Related visual reference

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Cross-references

Nearby regulation terms

Demagnetise: Remove magnetism from a movement.
Dial up / dial down: Two of the standard timing positions.
Drop: The small amount of free travel an escapement's parts have after unlocking and before the next locking contact.
Dynamic poising: Poising performed while the balance is oscillating, correcting for hairspring as well as balance imbalance.
Elinvar: A nickel-steel alloy whose elasticity varies little with temperature.
Endshake: Permitted axial movement of an arbor between its bearing limits; distinct from sideways bearing clearance.