Glossary of Clock Terms

Atomic Clock	Once a clock that worked much like a quartz watch, but receiving its frequency from the bombardment of radio activated isotopes and providing an degree of accuracy unmatched by any timepiece on the planet. Today "Atomic Clocks" are really earth bound receivers of electronic singles with ultra precise information, think GPS, cell phones, etc.
Case	The protective housing for the movement. May be a simple wood and glass case or extremely decorative using polished fine marble and additional statue embellishments.
Crank	See Winding Crank.
Dead Beat escapement	Also known as the Graham Escapement is characterized by its action of lock and slide as it operates. Catching, locking, and releasing each impulse of its escape wheel.
Dial	The numbered gage from which the time is displayed.
Escapement	The escapement drives the timekeeping element whether it’s a clocks pendulum or a watches balance wheel. Releasing the power supplied by the coiled spring or suspended weight which rotates a gear train. Without the escapement, the system would unwind uncontrollably. The escapement is controlled by the periodic swing of the pendulum or balance wheel which regulates this motion. It allows the gears to advance or 'escape' a fixed amount with each swing, and to then move the timepiece's hands forward at a steady rate. A second function of the escapement is to keep the pendulum or balance wheel moving by giving it a small push with each swing.
Grande Sonnerie	A full or grand strike which marks each passed quarter hour. Not to be confused with a chiming clock. At 9:15 the clock strikes 9 times for the hour followed by the one quarter, 9:30 the clock strikes 9 times for the hour followed by 2 quarters, 9:45 the clock strikes 9 times for the hour followed by the 3 quarter strikes and so on. Normally a clock with this feature has a selectable setting for no strike, hours only, or hours and quarters and an additional repeat push-button.
Hour Hand	The indicator from which the hours are read.
Key	See Winding Key
Main Spring	The ribbon of steel which when wound powers the clock. The length of the spring determines the duration of the period which the timepiece runs down and requires rewinding. Typical running durations are 30 hours, or 7 days with some clocks going longer as much as 1 year. Modern clocks with 31 day movements should be avoided as the additional duration increases friction and wear to the movement
Minute Hand	The indicator from which the minutes are read.
Moon Dial	Revolving Disk indicating the age of the moon, often inaccurate.
Pendulum Unit	The regulating device. By adjusting its length and affecting the period of the swing, the timepiece may be adjusted to keep exact time.
Pendulum Disk	The adjustable regulating weight.
Pendulum Rod	The stick portion of the pendulum, its length is paramount to the clock keeping time and cannot be haphazardly replaced or repaired without affecting the time keeping. Even broken parts can be help to ensure a proper replacement can be procured.
Repeating Strike	The time can be recalled by means of a pushbutton. This allowed one to get the time in the dead of night without having to fumble around for a candle. An hour repeater only repeats the last passed hour, a quarter repeater will repeat the last passed hour and quarter and a minute repeater can strike out the time to the last hour, quarter, and minute passed.
Regulating Nut	The thumb-screw normally at the base of a pendulum unit. The pendulum disk rests on this screw.
Second Hand	The indicator from which seconds are read.
Sizing Key	Multi-pronged key used to determine size, should never be used as a winding key as serious harm could result if the mainspring breaks.
Suspension Post	Mounting point for the suspension and pendulum. Its bridge may be connected to the movement or directly to the case back.
Suspension Spring	A thin metal spring which allows a otherwise rigid pendulum a flexible pivoting point, connected to the suspension post by means of a tapered pin or screwed in pin.
Verge Escapement	The verge (or crown wheel) escapement is the earliest known type of mechanical escapement, it is the mechanism in a mechanical clock that controls the advancing the gear train with each tick. While its origin is unknown, Verge Escapements have been used from 1550 about 1800 in both pendulum clocks and balance wheel pocket watches.
Weight	A heavy iron or lead mass attached to a cable or chain provides power via the falling mass. The same general rules apply as to the number of weights as related to the clock functions.
Winding Arbor	The shaft which carries the power source and is wound with the key. Look on the dial for the arbor hole with its square end which mates with the proper sized winding key. Most time-only clocks will have one, a second arbor normally indicates an additional hour and half-hour strike and a third arbor indicates a musical chime like Westminster played each passed quarter hour.
Winding Key	The means to rewind the springs of a clock.
Winding Crank	The means to rewind the weights of a cable driven clock.