Component record · Escapement
Banking Pins
VerifiedA pair of fixed pins (or an adjustable banking-to-drop mechanism) that limit the pallet fork's swing to a small, precise arc.
What it does
Prevents the pallet fork from over-rotating, ensuring the escape wheel teeth engage the pallets with correct locking and drop at each end of the fork's travel.
How it works
As the pallet fork swings between its two extreme positions, its body or an attached limiting surface strikes the banking pins, arresting further motion at a point set to give correct locking depth on the escape wheel teeth.
Banking pin position is adjustable in many movements (by moving the pins themselves or, in some designs, by adjusting banking screws) so that a watchmaker can set the correct 'drop' — the small amount of free travel the escape wheel tooth makes as it falls onto the next pallet.
Too little drop causes rubbing and friction losses; too much causes noisy, inefficient operation and can affect amplitude and rate.
Evolution
Banking-pin adjustment methods have been refined for precision but the underlying function has remained essentially unchanged since the lever escapement's early development.
Known variations
- Fixed banking pins pressed into the plate
- Adjustable banking pins or banking-screw systems for fine-tuning drop
Identification for collectors
- Two small pins visible flanking the pallet fork's travel, usually near the pallet bridge
Common failure modes
- Worn or bent pins altering the fork's set travel and hence escapement timing
- Incorrect adjustment causing excessive drop noise or insufficient drop and binding
Related photographs
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
- de Carle, D., Practical Watch Repairing
Where sources disagree, the disagreement is stated rather than resolved silently.