A
| B
| C
| D
| E
| F
| G
| H
| I
| J
| K
| L
| M
| N
| O
| P
| Q
| R
| S
| T
| U
| V
| W
| X
| Y
| Z
- A
- Anchor
- A part of an escapement of the same name. It looks like an upside-down anchor.
- Arbor
- The name given to mechanical shafts in horology.
- B
- Balance
- Looks like a wheel and provides the mass for escapements which do not depend on pendulums.
- Balance spring
- A spiral spring, one end of which is fixed to the balance and the other end to the frame, which with the balance forms an oscillator.
- Barrel
- The case in which the mainspring is contained.
- Beat
- The even tick-tock of a clock or watch.
- Bezel
- A frame holding glass in front of the watch or clock face.
- Brocot escapement
- A type of deadbeat escapement using semi-cylindrical pins.
- Bush
- An annular insertion of brass into the plate to provide a fresh bearing surface for a pivot.
- C
- Cannon pinion
- The pinion, having a long extension, which fits on the centre arbor and holds the minute hand.
- Case screws
- The screws which hold the movement in the case.
- Centre seconds
- Having a second hand concentric with the hour and minute hands.
- Centre wheel
- The wheel on the centre arbor.
- Chiming
- Producing a musical sequence of notes, often at the quarter hours.
- Chronograph
- A clock or watch which records intervals of time. The hands can be stopped or started at will without stopping the mechanism and interfering with the timekeeping.
- Chronometer
- A very accurate timekeeper.
- Click
- A sprung detent which stops a ratchet wheel from turning backwards.
- Cock
- A small plate holding one or two pivots only.
- Countwheel striking
- An early and simple method of controlling the number of strokes sounded at the hour.
- Crown wheel
- A wheel where the teeth face along the arbor and used in the verge escapement.
- Cylinder escapement
- A balance wheel escapement driven by the escape wheel engaging in a cutaway cylinder.
- D
- Deatbeat
- A type of escapement without recoil.
- Dial
- The plate on which the numerals are marked.
- E
- Escapement
- The device which controls the speed of the clock or watch time train.
- F
- Fly
- The rotating flat plate or governor which controls the speed of the striking or chiming trains.
- Full plate
- Where the back plate covers the whole of the watch movement.
- Fusee
- A tapered pulley device which evens out the pull of the mainspring.
- G
- Going train
- The train of wheels and pinions driving the escapement.
- Gut line
- A line used to connect weights to the movement or to connect the mainspring to the fusee. Can be made from natural gut or can be artificial.
- H
- Hairspring
- See Balance Spring
- Half plate
- Where the back plate of the watch covers only about half of the movement. Separate small plates called Cocks hold the escapement and fourth wheel pivots.
- Hole
- A circular hole in the plate in which a pivot runs.
- I
- Impulse
- The small push given to the balance or pendulum once or twice each oscillation.
- J
- Jewel
- A precious or artificial stone used as a pivot hole or as an end cap for a pivot.
- K
- Keywind
- Wound by a key.
- L
- Lever escapement
- An escapement where an anchor shaped lever provides the impulse to the balance.
- M
- Mainspring
- A spiral spring, usually in a barrel, used as the motive force of a clock or watch.
- Motion work
- The wheels and pinions linking the minute and hour hands together.
- Movement
- The 'works' of a clock or watch.
- N
- No definitions.
- O
- Olive
- A small plunger in a watch case used in conjunction with the winding button to allow the hands to be set.
- P
- Pallet
- The teeth, usually only two, that engage in the escape wheel.
- Pendulum
- A mass on the end of a rod which when acted upon by gravity provides the constant period oscillator for clocks.
- Perpetual calendar
- An automatic calendar in a watch or clock which takes account of the varying lengths of months and of leap years.
- Pin pallet
- A type of lever escapement using pins on the lever to obtain impulse.
- Pinions
- A name for small gears, usually made of steel, driven by the larger wheels.
- Pivot
- A fine extension of an arbor, running in a pivot hole.
- Plate
- The back or front sheet of metal of a watch or clock movement in which the pivots run.
- Platform Escapement
- A self-contained and removable balance escapement.
- Q
- No definitions.
- R
- Rack striking
- A mechanism which superseded countwheel striking to control the number of strokes sounded at the hour. Allowed the use of repeater work.
- Ratchet wheel
- A toothed wheel used in conjunction with a click to allow rotation in one direction only.
- Rating nut
- The nut above or below a pendulum used to alter its length and so the rate at which the clock goes.
- Regulation
- The process of changing the rate of a clock or watch.
- Regulator
- The lever or other device used principally with balance escapements to alter the rate.
- Repeater
- A clock or watch which can strike the last hour, with in some cases, the quarter and even the minutes at will.
- Run
- Usually uncontrolled running of a movement
- S
- Split seconds
- Having two second hands, each of which can be stopped at will.
- Spring lug
- The telescopic bar on a watch used to hold the strap.
- Stemwind
- A watch wound by a knob or button, not with a key.
- Stop work
- A mechanism connected to the winding to prevent overwinding.
- Stopwatch
- A watch whose mechanism can be stopped or started at will. Used for timing events. See chronograph.
- Striking
- Sounding the hours and perhaps the half-hours as well.
- Striking train
- The train of wheels and pinions controlling the striking
- Suspension
- A fine strip of steel, or sometimes silk thread, on which the pendulum hangs.
- T
- Three-quarter plate
- Where the back plate of a watch covers 3/4 of the movement, with the escapement pivoted in separate cocks.
- U
- No definitions.
- V
- Verge
- An early type of escapement where a crown wheel drives steel flags on the balance or pendulum arbor.
- Visible escapement
- An escapement mounted on the dial of a clock. Often a Brocot escapement.
- W
- Waterproof
- A vague term. See the notes on water resistant watches.
- Wheels
- The larger gears that drive pinions in movements.
- Winding button
- The knob on a watch case that is used for winding.
- Winding square
- The squared end of the mainspring arbor on which the key is fitted.
- Winding stem
- The small shaft in the movement on which the winding button is fixed.
- X
- No definitions.
- Y
- No definitions.
- Z
- No definitions.