Glossary

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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 of 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 The frame holding the glass in front of a clock or watch.
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 the 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

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.

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.

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.

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