Pocket Watch Parts — A to Z
This glossary covers the main parts found in a typical lever-escapement pocket watch. Understanding these terms will help you read auction descriptions, repair manuals, and collector literature with confidence. For a fully illustrated breakdown of all four mechanical assemblies with interaction descriptions, see the Complete Parts Diagram.
The Parts
- Arbor
- The axle on which a wheel or pinion is mounted.
- Balance Spring
- Also called the hairspring — a very fine coiled spring that controls the oscillation of the balance wheel. The heart of the watch's timekeeping accuracy.
- Balance Wheel
- The oscillating wheel that divides time into equal segments. Performs the same function as a pendulum in a clock.
- Barrel
- A cylindrical box containing the mainspring. The outer wall (the barrel) drives the gear train.
- Bezel
- The ring that surrounds and holds the crystal on the front of the watch.
- Bridge
- A metal plate that supports the pivot of one or more wheels at one end only.
- Cap Jewel
- A flat jewel that acts as an end bearing for the balance staff.
- Click
- A small spring-loaded pawl that allows the ratchet wheel to turn in one direction only, preventing the mainspring from unwinding spontaneously.
- Cock
- A plate supported at one end only, used to hold the balance wheel.
- Crown
- The knurled button used to wind the mainspring and set the time.
- Crown Wheel
- In a verge escapement, the wheel with teeth at right angles used to interact with the pallets.
- Cylinder
- A type of escapement used in thin watches.
- Dial
- The face of the watch, showing the hours, minutes and seconds.
- Double Roller
- A safety device on the roller table that prevents accidental unlocking of the lever. Required by railroad standards.
- Draw
- The angular position of the pallet jewels that maintains the lever against the banking pins.
- Escapement
- The mechanism that controls the release of energy from the mainspring — typically the lever escapement in American pocket watches.
- Escape Wheel
- The final wheel in the gear train; interacts with the pallets to release one tooth at a time.
- Fork
- The part of the lever that engages with the roller jewel on the balance wheel.
- Fourth Wheel
- The wheel that drives the seconds hand.
- Fusee
- A conical pulley used in older watches to equalise the pull of the mainspring as it unwinds.
- Gear Train
- The series of wheels and pinions that transmit energy from the mainspring to the escapement.
- Going Barrel
- A barrel that drives the gear train directly without a fusee.
- Hairspring
- See Balance Spring.
- Jewels
- Hard synthetic or natural rubies set in the movement as bearings to reduce friction and wear.
- Lever
- The escape lever — a T-shaped part that engages alternately with the escape wheel teeth and the balance roller.
- Mainspring
- The coiled spring that stores energy when wound and releases it to drive the movement.
- Movement
- The entire mechanical assembly of a watch, excluding the case and dial.
- Pallet
- The two angled jewel-tipped arms on the lever that alternately lock and release escape wheel teeth.
- Pillar Plate
- The main plate of the movement to which all components are attached. Also called the bottom plate.
- Pinion
- A small gear wheel with fewer teeth, meshed with a larger wheel.
- Pivot
- The reduced end of an arbor that runs in a jewel or brass bearing.
- Plate
- A flat metal component that bridges the movement. Top plates cover the gear train.
- Ratchet Wheel
- A wheel with angled teeth that interacts with the click to allow winding in one direction only.
- Regulator
- A lever that adjusts the effective length of the hairspring to alter the rate of the watch.
- Roller Jewel
- A jewel set in the roller table that engages with the fork of the lever.
- Setting
- "Adjusted to N positions" means the watch has been regulated to keep time accurately in N different orientations (dial up, dial down, crown up, etc.).
- Stem
- The shaft connecting the crown to the movement winding and setting mechanism.
- Stud
- The post fixed to the cock from which the outer coil of the hairspring is anchored.
- Third Wheel
- The wheel between the centre wheel and the fourth wheel in the gear train.
- Winding Stem
- See Stem.