Motors, Gears, and More: Glossary of Horological Terms

Acorn Clock: A type of American shelf clock characterized by its distinctive acorn-like shape

Act of Parliament Clock: Also known as the tavern clock, this clock style is said to have been created in response to an unpopular tax law

Anchor Escapement: A mechanism within a clock or watch that regulates time by allowing the escapement to release energy in precise intervals, commonly found in longcase clocks

Anniversary Clock: A clock that features a torsion pendulum, allowing it to run for up to a year on a single winding. It is also referred to as a 400-day clock.

Arbor: A spindle or axle that supports the movement of parts like wheels and pinions within a clock’s mechanism

Atmos Clock: A clock that operates using variations in atmospheric pressure, eliminating the need for a traditional winding mechanism

Autowinder: A system powered by an electric motor that automatically winds a clock without manual intervention

Back Cock: A brass bracket that supports the rear pivot of the escape wheel in a clock’s mechanism

Back Plate: A component that forms part of the clock’s movement assembly.

Balance: A non-toothed wheel found in watches and chronometers that oscillates back and forth, with its motion regulated by a balance spring, determining the rate at which the clock keeps time

Balance Spring: A coiled spring that controls the oscillations of the balance, influencing the timekeeping accuracy.

Balance Staff: The arbor around which the balance wheel rotates, allowing it to oscillate freely.

Balloon Clock: A clock crafted in the shape of a hot-air balloon, often of French origin

Banjo Clock: A clock designed by American clock maker Simon Willard in the late 18th century that’s shaped to resemble a banjo

Barrel: A short, cylindrical container made of brass that houses the mainspring of a clock

Barometer: An instrument used to measure atmospheric pressure, often employed to predict weather changes

Beat: The even, rhythmic sound produced by the escapement mechanism, where the “tick” and “tock” should be of equal duration. Proper beat-setting ensures accurate timekeeping.

Black Forest Clock: A traditional German clock, typically from the Black Forest region, featuring wooden movements made by local artisans

Bluing: The process of heating steel to a specific temperature until it changes color, often to a blue hue, as part of the finishing process

Bob: The weighted component at the bottom of a pendulum rod, which is crucial for regulating the timekeeping of the clock

Bodging: An informal term referring to poorly executed or hasty repairs, often resulting in subpar performance

Bornholm Clocks: Clocks originating from the Danish island of Bornholm, known for their unique style and craftsmanship

Bracket Clock: A style of British spring-driven clock once believed to be mounted on a bracket attached to the wall

Break-Arch: A type of clock dial featuring an arch at the top, where the base of the arch is narrower than the square dial beneath

Broach: To widen a hole, typically for a pivot, using a specialized tool called a broach

Bushing: The process of inserting small brass cylinders, known as bushes or buchons, into worn or misshapen holes in clock plates to ensure smooth movement of the pivots

Caddy Top: A decorative feature at the top of a longcase or bracket clock, often shaped in an “S” form, with the bottom wider than the top

Cannon Pinion: A pinion in a clock’s motion work shaped like a hollow cylinder (resembling a cannon), onto which the minute hand is attached

Carriage Clock: A small, portable clock typically encased in brass or decorated metal, designed with a handle for travel and often featuring a platform escapement

Cartel Clock: A decorative wall clock, often French or English, made of ormolu and known for its intricate design

Cart Wheel Dial: A longcase clock dial that has cut-out sections behind the chapter ring, giving it a visual resemblance to a cart wheel

Center Arbor: The arbor of the center wheel in a clock, which completes one full rotation every 12 hours and to which the cannon pinion is attached

Center Wheel: The third wheel in a clock’s timekeeping train, which holds the minute hand on its arbor

Champlevé: A type of decorative enameling, typically seen on carriage clocks, where enamel is applied in recessed sections of engraved brass

Chapter Ring: The circular ring on a clock’s dial that displays the hours, historically associated with the chapters of monks’ duties

Chime: A melodic tune played by a clock to mark the hours and quarters

Chinoiserie: A decorative style inspired by Chinese design, often seen in lacquered clock cases

Chronometer: A highly precise timekeeping device typically used in maritime navigation, often housed in a gimbal-mounted wooden box to maintain accuracy at sea

Click: A ratchet pawl that engages with a spring (clickspring) to prevent backward movement when winding a clock’s mainspring

Collet: A circular ring used to secure parts of a clock, such as wheels and pinions, onto arbors

Comtoise Clock: A traditional clock made in the Franche-Comté region of France, also often referred to as a Morez or Morbier clock

Congreve Clock: A clock invented by William Congreve in which a ball moves through a zigzag channel on a brass plate as part of the escapement mechanism

Countwheel: A component in the strike train of a clock that determines how many times the clock will strike at a given hour

Crown Wheel: The escape wheel used in a verge escapement, with teeth set at a right angle to the plane of the wheel, resembling the shape of a crown

Crown Wheel Escapement: Also known as the verge escapement, this mechanism allows for the controlled release of energy from the clock’s wheels.

Crutch: A lever that transfers impulse from the escape wheel to the pendulum and from the pendulum back to the pallets, regulating the clock’s timekeeping

Cuckoo Clock: A traditional Black Forest clock, often designed to resemble a house, in which a carved cuckoo bird emerges and makes a “cuckoo” sound to indicate the time

Depthing: The process of aligning clock wheels and pinions to ensure that they mesh correctly, often using a depthing tool to verify the fit

Detent: A mechanical stop used to secure the ratchet of the maintaining power in a chronometer so that it holds the winding

Dial: The face of a clock or watch that displays the time, typically marked with numbers or symbols for hour markers

Draw: A part of the escapement action in which the pallet is pulled inward by the escape wheel, preparing it for the next step in the timekeeping process

Drop: The part of the escapement mechanism where the pallet drops onto the escape wheel tooth, controlling the flow of energy

Drop-Trunk: A type of wall clock similar to an English dial clock but with the pendulum box extending beneath the dial

Engine-Turning: A technique used to inscribe a decorative pattern onto the plates of watches

English Dial Clock: A type of wall clock where only the dial is visible, while the movement and pendulum are hidden behind it

Equation of Time: The discrepancy between apparent solar time and mean time, caused by Earth’s elliptical orbit, which can differ by up to 15 minutes

Escapement: The mechanism that controls the release of power from the gear train of a clock in regular, precise bursts, regulating the timekeeping

Escape Wheel: The wheel in a clock’s gear train that releases energy from the going train at a controlled pace, with its teeth engaging the pallets of the escapement.

Falseplate: A metal plate affixed to the back of a clock dial that supports the movement and provides stability for the mechanism.

Finial: A decorative feature at the top of a clock case, often seen on longcase or bracket clocks

Fly: A rotating component with vanes, typically found at the end of the strike train, that acts as an air brake to slow down the mechanism when the clock strikes

Fly Dial: A painted dial of a longcase clock featuring a fly or bee as part of the design

Foliate: Relating to the design or decoration of clock cases using leaf or foliage motifs

Foliot: A bar within the verge escapement that carries the pallets, contributing to the clock’s time regulation

Four-Glass Clock: A clock enclosed in a case with four glass panels, allowing full view of the clock’s mechanism

Franklin Three-Wheeler: A clock created by Benjamin Franklin with only three wheels in its going train, necessitating a unique dial layout with fewer hour markings

Fret: A decorative opening or pattern in a clock case that allows sound to escape from the bell

Fusee: A conical component used to regulate the power delivered from the mainspring to the clock train, ensuring consistent energy release

Fusee Chain: A fine chain, similar to a bicycle chain, that connects the spring barrel to a fusee so that the mainspring’s power is delivered evenly throughout its unwinding

Gallery Clock: A clock designed to be mounted in a public space, such as a church gallery, where visibility is important

Gathering Pallet: A component in the striking mechanism that collects the rack teeth, ensuring the correct number of strikes at the appropriate hour

Girandole: A type of banjo clock designed by Lemuel Curtis

Gong: A bar of bell metal used in clocks that chime or strike that produces a resonant sound when struck

Governor: A device that regulates the speed of gears in a clock or the speed of an elevator‘s motion

Gnomon: The part of a sundial that casts a shadow to indicate the time of day

Grand Sonnerie: A type of clock that chimes automatically on the hours and quarter-hours, requiring no manual winding to activate the chime

Gut: A cord, traditionally made from gut, used in place of a fusee chain to transfer power from the mainspring

Hairspring: Another term for the balance spring, which controls the oscillations of the balance wheel to regulate time

Half-Quarter Markers: Markers on the dial of certain longcase clocks that indicate halfway points between the quarter-hour markers, such as seven and a half minutes past the hour

Heliochronometer: A specialized type of sundial that uses a lens to focus sunlight onto a scale indicating the time of day

Hood: The upper, often removable part of a longcase clock case, which surrounds and protects the clock’s dial

Hooded Clock: A wall clock that resembles a longcase clock, with a weight-driven mechanism enclosed in a wooden case

Hour Wheel: A part of the clock’s motion work that connects to the hour hand, allowing it to rotate with the timekeeping mechanism

Hunter: A type of pocket watch with a protective cover over the crystal, often with a small opening (lenticle) to view the time while the cover is closed

Huygens Loop: A design for the rope used in longcase clocks that provides maintaining power for the clock

Impulse: The brief push imparted by the escapement’s tooth on the pallet, maintaining the motion of the pendulum, balance wheel, or other regulating component

Jacot Tool: A tool used to polish and burnish the pivots of a clock or watch, ensuring smooth movement and reducing friction

Japanning: The application of a lacquer finish on clock cases, particularly longcase clocks

Jeweling: The process of placing synthetic ruby jewels into pivot holes to reduce wear and friction in mechanical watches, chronometers, and regulators

Joker: A small, whimsical Black Forest carriage clock, often featuring intricate carvings or unusual designs

Lancet Clock: An American-style clock with a case featuring a pointed top, similar in shape to a lancet, commonly found in antique clock collections

Lantern Clock: A classic British domestic clock, originally crafted from brass and iron, with a design that is thought to resemble the shape of a lantern

Lantern Pinion: A specific type of pinion that uses wire pins, also called trundles, in place of traditional leaves for the gear mechanism

Leaf: An individual tooth on a pinion that meshes with the teeth (leaves) in other gears to transmit power

Lock: A part of the escapement mechanism in which the pallets engage with the escape wheel, halting its movement momentarily and regulating timekeeping

Loupe: A magnifying glass used by watchmakers to closely inspect the fine details of clock parts

Longcase Clock: A tall, free-standing clock, often referred to as a grandfather clock, typically featuring a pendulum for accurate timekeeping

Mainspring: A tightly wound flat spring that stores energy to power spring-driven clocks, often housed in a barrel to control its release

Maintaining Power: A mechanism within a clock that ensures that the hands continue to move while the clock is being wound

Mantel Clock: A small, tabletop clock designed to sit on a mantelpiece or shelf, often used as a decorative piece in homes

Marquetry: An intricate inlay technique used to decorate clock cases

Mass Dial: A time marker carved into the stone of a church or similar building that shows the times for Mass

Master Clock: An electrical clock that sends out time signals to synchronize other clocks, known as “slave clocks,” within a system

Matting: A process used to create a matte or stippled finish on brass, particularly seen on clock dials

Meccano: A set of interlocking metal pieces that can be assembled into clocks, originally designed as a children’s construction toy

Minute Wheel: A gear and pinion system that converts the minute hand’s hourly movement into the hour hand’s 12-hour rotation

Morbier Clock: A type of French clock, also known as a Comtoise clock, with a distinctive mechanical design

Morez Clock: Another name for the Comtoise clock, a traditional French timepiece with a striking mechanism

Motion Work: A gear system that transfers the hourly rotation from the cannon pinion to the 12-hour movement of the hour wheel

Movement: The internal mechanism of a clock or watch, which drives its hands and powers its timekeeping function

Musical Clock: A clock designed to play tunes at set intervals, typically on the hour

Mystery Clock: A clock with a concealed movement, creating the illusion that the hands are moving without a visible source of power

Napoleon’s Hat Clock: A style of mantel clock, first created in Britain in the 1930s, whose case resembles the shape of Napoleon Bonaparte’s hat

Nib: The part of the pallet in an escapement that interacts with the teeth of the escape wheel, helping to regulate its motion

Norfolk Clock: A wall clock resembling a longcase clock but with a shorter trunk, typically mounted on the wall

Novelty Clock: A clock designed with unusual features, often prioritizing aesthetics or creativity over traditional timekeeping functions

Ogee Clock: An American-style shelf clock with a rectangular case, featuring a dial at the top and a reverse-painted glass tablet below, framed by an S-shaped molding

Oil Sink: A small, hemispherical depression in the clock movement’s plate that holds oil to lubricate the pivot

Pallets: Components of a clock’s escapement that momentarily halt the movement of the escape wheel, allowing power to escape at a regular rate

Pendulum: A swinging mechanism, typically consisting of a rod and a bob, used in many clocks as part of the escapement system to regulate time

Pillars: Cylindrical posts that keep the movement plates of a clock separated, allowing the gears and mechanisms to operate freely

Pinion: A small gear in a clock mechanism that’s paired with a larger wheel to transmit power in the going, striking, or chiming train

Plates: The structural components that hold the gears and pinions of a clock’s movement, supporting the pivots and other parts

Platform Escapement: A type of escapement that is mounted on a platform, typically used in small or portable clocks

Pull Repeat: A type of repeat mechanism activated by pulling a cord, allowing the clock to repeat the strikes of the hours or quarter hours

Rack: A toothed lever that is used to count the number of hours or strikes in a clock

Recoil: A feature in some escapement systems where the escape wheel briefly moves backward before resuming its forward motion

Regulator: An extremely accurate clock used in workshops to maintain the correct time and set other clocks

Repeat: A mechanism that allows a clock to repeat its strikes after the hour has passed, often activated by a button or lever

Rod: The part of a pendulum that connects the bob to the suspension, allowing it to swing back and forth

Schild Dial: A clock dial shaped like a shield, often used in traditional Black Forest clocks for a distinctive look

Seatboard: The wooden base on which the movement of a longcase clock is mounted, providing stability and support

Singing Bird Clock: A musical clock featuring a mechanical bird that appears to sing, often accompanied by animated movement of its beak

Skeleton Clock: A clock that has been designed with openwork plates, allowing the inner workings of the movement to be seen

Sonnerie: A type of clock, often a carriage clock, that strikes both the hour and the quarter hours automatically

Strike: The action of a clock ringing or chiming with a bell or gong

Strike/Silent: A feature that allows the user to turn the striking mechanism on or off, typically controlled by a hand on a subsidiary dial

Strut Clock: A clock supported by a strut at the back, holding it upright or propped on display

Sundial: An ancient time-measuring device that uses the position of the sun’s shadow on a dial to show the time of day

Subsidiary Dial: A small additional dial on a clock’s main dial, often used to display seconds, dates, or other features

Suspension: The system that suspends the pendulum from the clock’s movement, typically using a spring or silk thread

Swan Neck: A decorative element found at the top center of some longcase clocks’ hoods that’s shaped like the neck of a swan

Synchronous Clock: An electric clock that uses the frequency of alternating current to regulate its timekeeping

Tablet: A decorative glass panel on American clocks, often featuring reverse painting or mirrored designs.

Tavern Clock: A large, public wall clock, often octagonal in shape, historically used in taverns and other communal spaces to show the time

Ticket Clock: A clock that uses plastic cards that flip over to display the time as it changes.

Time Ball: A large ball that is raised to the top of a pole and dropped at a specific time, allowing sailors to check the accuracy of their chronometers

Time Recorder: A clock used in workplaces to record employees’ arrival and departure times, often seen in factory settings

Ting-Tang Striking: A type of clock striking system that uses two bells or gongs to produce a distinctive dual-tone chime on the quarters

Torsion Pendulum: A pendulum that spins back and forth, often used in anniversary clocks to provide timekeeping through torsional motion

Tourbillion: A rotating mechanism that compensates for positional changes in a clock or watch by continuously rotating the escapement

Train: The series of gears and pinions that carry power from the energy source to the escapement (going train), striking system (striking train), or chime mechanism (chime train) of a clock or the winding drum of an elevator

Trundle: A pin used in place of teeth in a lantern pinion, which helps transmit power through the clock’s gearing system

Vienna Clock: A highly accurate wall clock developed in Austria-Hungary featuring a distinctive escapement mechanism for precise timekeeping

Wagon-Spring Clock: An American clock designed by Joseph Ives that uses a leaf-spring mechanism for powering the clock’s movement

Wheels: The large gears in a clock’s mechanism, often paired with smaller pinions to transfer motion and power throughout the movement

Additional Resources

• Illustrated Horological Glossary
• Watch Glossary
• Dictionary of Horology
• Glossary of Horological Terms
• Complete A-Z List of Horological Terms You Should Know
• Watch Parts: A Glossary of Terms and Functions
• Mechanical Clocks and How They Work
• Glossary of Pocket Watch Parts and Terminology
• Antique Pocket Watch Glossary
• Practical Horology in the 1870s