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Glossary

"Old World Quality and Craftsmanship©"
BSR GROUP, INC.

   CLOCK & WATCH GLOSSARY

We update this glossary frequently, based upon inquiries from our customer.  If there is a term not listed, or, requires further explanation, please drop us an e-mail to that effect. 

  Underlined Links in this column are cross references to other entries
Anchor Type of pallet used in escapements of clocks & watches shaped like a ship's anchor.
Arbor Spindle or axle on that clock wheels are mounted. (Also see Barrel Arbor).
Back Cock Found in some clocks, a small plate mounted on back plate of clock in that the pallet pivots.
Back Plate The plate in that the movements back pivots run (the back plate is that that is furthest from the dial).
Balance Wheel Oscillating part usually a wheel (with tiny screws specifically mounted around the circumference, so as to compensate for deviations in temperature and humidity) that controls the timekeeping of clocks & watches. (See Platform Escapements)
Barrel Cylindrical part that in European spring driven clocks that contains the mainspring, and, in weight driven clocks has the cables wrapped around it.
Barrel Arbor Spindle with a hook, or, slot that catches the mainspring and has a square external end for winding.
Beat The beat of a clock is its tick, a clock must be 'in beat' for it to be reliable and a good timekeeper, a clock is in beat when the tick and tock of the clock are at equal intervals.
Bezel Metal frame often holding a glass.
Bob The weight at the end of the pendulum that is moved up or down in order to regulate the clock.
Bridge In watches, the upper plate which contains either bushings, or, jewels upon which the arbor pivot rotates. In most watches, and some clocks that employ a platform escapement a separate bridge is used to support the escapement components. Watches may have up to five or six bridges. Each bridge adds to the expense of the watch, however, expedites repairs as a complete disassembly may not become necessary.
Brocot Escapement Type of dead beat escapement used in many French clocks using semicircular pins in the pallets.
Bushing A brass ‘bearing’ into which an arbor pivot fits and rotates.
Cable Cables made of gut or wires are used in both weight driven clocks and fusee clocks.
Cannon Pinion Pinion that holds the minute hand usually a friction fit over the center wheel, or, loose over center pipe of a clock in order to allow the minute hand to be moved.
Carriage Clock Type of clock fitted with a platform escapement to enable it to be moved without the problems of putting the clock in-beat usually in a gilded brass case with glass panels all round.
Center Wheel Wheel on that the cannon pinion is fitted, usually next to the barrel or great wheel, depending on the type of clock.
Center Seconds A seconds hand fitted to an arbor pivoted at the center of the dial usually at the same point as the hour and minute hands.
Chapter Ring Circle on a dial that carries the markings for the hour and minutes.
Chiming Clock Clock that sounds a tune at each quarter of an hour such Westminster, Whittington, etc.
Chronometer Clock or watch often used on board ship that gives excellent timekeeping.
Click Ratchet or pawl used to prevent the mainspring, or weight, unwinding when wound. The click is held in position by the click-spring.
Cock Bracket or small plate attached to larger plate to hold parts that are fitted outside the main plates of the clock.
Collet A washer used in conjunction with a pin to hold parts such as the minute hand to an arbor.
Contrate Wheel Wheel where the teeth are at right angles to the plane of the wheel to transmit the power of the clock train through 90 degrees used in verge escapement clocks and carriage clocks.
Count Wheel Wheel used in striking clocks with either a combination of shallow and deep cuts or slots, or, merely deep slots at different spacing used to stop the strike train after striking the appropriate number. Strike halts when a rod, commonly called a feeler rod enters a deep slot.
Crown Wheel Escape wheel of a verge escapement transmitting power to the verge pallets.
Crutch Part attached to the pallets used to transmit power to the pendulum.
Dead Beat Type of escapement where there is no recoil caused by the swing of the pendulum, George Graham invented one such escapement.
Detent A piece that positions and holds another part in position.
Dial The visible 'face' of the clock on that the numerals or chapter ring are situated and from that one can tell the time.
Drop 1 The free travel of the escape wheel between the impulse and the locking of the pallets.
Drop 2 English Dial clock where the pendulum hangs beyond the circle of the dial and is cased below the dial sometimes with a glass aperture to show the brass faced pendulum.
Drop3 Distance required for the weights of a clock to fall in the clock's duration.
Drum Another term for barrel.
Dummy Blow Grande Sonnerie clocks have a silent strike where both hammers are held clear of the gongs, this happens after the hours have been struck and before the quarters are struck.
Dummy Pendulum A small disc seen through a slit in the dial of some clocks attached to the pallets to show the movement of the pendulum.
Duration Time over that the clock will run on one winding.
Escape Wheel Wheel that transmits power through the pallet to the pendulum.
Escapement Term used for the type of parts that transmit power to the pendulum or other device that regulates timekeeping; such as the verge, anchor, dead beat and platform escapements.
False Pendulum See Dummy Pendulum.
Feeler Rod A component of the strike sequence that, in concert with the count wheel controls the number of strikes.
Finial Ornamental piece of turned wood or brass fitted to the top of cases.
Foliot Early form of balance using oscillating arms attached to a verge escapement with adjustable weights to regulate timekeeping.
Fly or Fly Wheel Vane used to regulate the speed of the striking train using air resistance. (See 'Governor')
Friction Washer Spring washer, used mainly in English clocks to connect the cannon pinion to the center wheel whilst allowing the minute hand to be moved.
Front Plate The clock's main front plate positioned just under the dial.
Fusee Cone shaped part usually with grooves to accept a cable attached to the barrel, fixed to the great wheel of the clock by a slip washer with the winding ratchet inside. Its purpose is to equalize the torque exerted by the mainspring as the spring runs down, when fully wound the line pulls on the small end of the cone and when unwound the line is at the large end of the cone thus the power applied to the train is more or less the same when it is fully wound as it is at the end of its duration.
Gathering Pallet Part of the striking mechanism that gathers one tooth of the rack per strike thus counting number of strikes, sometimes also used to lock the strike train at the completion of striking. Used in lieu of a count wheel. (See ‘Rack and Snail Escapement’)
Gimbals A type of universal joint used in ships' chronometers to keep the movement horizontal.
Gong Rod or coil of hard metal such as bronze or hardened steel struck by a hammer during chiming or striking.
Governor Flat, fan like pieces of brass that are released during the strike and chime sequence to control the speed of the chime or strike.
Grande Sonnerie Striking clock that strikes the last hour and the quarters at each quarter hour.
Grandfather Clock Common name given to Long-case clocks.
Great Wheel First wheel in the train attached to the barrel or fusee.
Gridiron Pendulum Pendulum invented by John Harrison to compensate for changes in temperature, arrangement of steel and brass rods fixed in different positions that expand different amounts keep the pendulum the same length.
Hairspring A very thin, coiled spring to which a balance wheel is connected.
Hammer Part that is lifted and then released to strike a gong or bell in a striking or chiming clock.
Hands The 'pointers' that enable the viewer to tell the time, many different patterns have been designed over the years and can be a good indicator of the age of a clock.
Hood The top of a Long-case clock that can be removed by pulling forward or sometimes upwards in early clocks.
Hoop Wheel Wheel in the striking train of a count wheel clock that a lever stops at the end of the striking.
Hour Wheel Wheel on to that the hour hand is fitted sometimes bearing on a separate cock that holds it away from the cannon pinion over that it is fitted; it is driven by the minute wheel.
Impulse The period during that the escape wheel imparts power to the pallets.
In Beat See Beat.
Jewel Usually a ruby, is found in watches, or platform escapement clocks, and is used in lieu of a bushing. A jewel will outlast a bushing at least 100-fold. Each jewel adds to the value of the clock or watch.
Lantern Clock Early weight driven 30 hour clock with brass case with 4 posts at the corners and bell at the top, with a verge escapement and in the earliest clocks a balance wheel foliot later with a pendulum made c.1630-1730.
Lantern Pinion Old form of pinion in that pins are held between 2 discs rather than leaves or teeth cut from the metal of the arbor.
Leaf Each tooth of a cut pinion is called a leaf.
Locking Plate Another term for a count wheel.
Long-case Clock Commonly known as a 'Grandfather Clock'.
Main Wheel See Great Wheel.
Mainspring A long strip of hardened & tempered steel coiled into a barrel or with a loop around a pillar used to give power to the train of a clock.
Maintaining Power A device used to provide power to a weight driven or fusee clock during winding, without it there is a possibility of damage to some escapements due to the swinging of the pendulum whilst no power is getting to the escapement.
Minute Wheel A wheel in the motion work often with a pin that releases the striking mechanism, driven by the cannon pinion it drives the hour wheel.
Mock Pendulum See Dummy Pendulum.
Motion Work The mechanism under the dial that keeps the hour and minute hands correctly aligned.
Movement The works of a clock or timepiece.
Oil Sink Small hollow area concentric with pivot hole in bushing or jewel, intended to retain the oil at the pivot.
 Pallet (aka Fork) In a pendulum or weight driven clock, pallets are the faces of the verge (Often jewels.) The part of the platform escapement that takes power from the escape wheel and delivers it to the movement with each oscillation of the balance wheel.
Passing Strike A clock striking just once each hour as the minute hand passes the hour is described as a passing strike clock.
Pendulum A rod with weight at the bottom usually suspended at the top by a spring or silk cord, a method of regulation is normally fitted, making the pendulum shorter makes the clock run faster.
Pillars Metal pieces that hold the plates together the correct distance apart.
Pin Drum
 
A drum with pins protruding that lift hammers in a chiming or musical clock as the drum revolves. The ‘pins’ often are not actually pins protruding, rather, raised points in the drum that performs an identical function.
Pin Wheel A wheel in the striking train fitted with pins to lift a hammer during striking.
Pinion Part of the train with leaves or teeth driven by the wheels of the train.
Pivot End of an arbor that revolves in a hole in the plates.
Plates Upper and lower, flat brass pieces between which the wheels and other internal parts are fitted.
Platform Escapement Used in lieu of pendulum escapements, consisting of a balance wheel, pallets, escape wheel, and, a hairspring mounted between two flat brass plates (See Bridges). Platform Escapements are most often found on French clocks, in particular carriage clocks. (Many new clocks utilize platform escapements). All watches utilize a platform escapement.
Potance Bracket or cock that carries the lower pivot of the crown wheel of a verge movement.
Pull Repeat A mechanism that when a cord is pulled repeats the last hour strike or quarters of a separate chiming train.
Pulley Wheel around which the cables of a weight driven clock run halving the drop required but also halving the force imparted on the train.
Push Repeat A mechanism usually on carriage clocks that when a button is pushed repeats the last hour strike.
Quarter Chime A train that is activated at each quarter of an hour playing a tune on more than 2 bells or gongs.
Rack Part of the striking mechanism with teeth that are counted by the gathering pallet and a tail that falls on to the snail selecting the count to be struck, invented in 1676.
Rack Hook Piece that holds the rack in position between strikes until the next tooth is picked up by the gathering pallet and that holds the rack in position when striking is completed.
Rack & Snail Escapement In lieu of a count wheel, the rack and snail control the number of strikes during a strike sequence. The snail is so called due to its physical resemblance to a common snail shell that has a sequence of shallow to deep recesses. At the commencement of the strike sequence, the rack is released and falls upon the snail. The amount of ‘drop’ or distance it falls determines the number of times the gathering pallet engages the rack hooks, hence the number of strikes.
Ratchet Wheel Wheel with angled teeth to prevent unwinding when held by the click.
Rate The amount by that a clock gains or loses.
Rating Nut A nut on a pendulum used to raise or lower a pendulum bob (Lower = Slower).
Recoil The amount the escape wheel is pushed backwards by the swing of the pendulum on a recoil escapement.
Regulator 1 A weight driven pendulum clock without a striking train designed for very accurate timekeeping, although so called Vienna regulators often have striking trains.
Regulator 2 The part of a clock designed to alter the rate of a clock (as in rating nut) but normally associated with balance wheel clocks like carriage clocks.
Repeater A clock with a mechanism that when activated repeats the striking of the last hour.
Seat board The board to which a movement is fixed. Typically found in Long Case clocks.
Snail A cam like wheel on to that the rack tail drops in order to select the number to strike. (See Rack & Snail Escapement)
Spandrel An ornamental piece fitted to the corner of dials, the designs vary greatly and can help in dating of clocks.
Star Wheel A star cut wheel held by a detent to position either a date wheel or a striking snail.
Stop Work A mechanism used to prevent a clock from being over wound most commonly found in fusee movements.
Strike A hammer hitting a gong or bell counting the hours.
Strike-Silent A mechanism that allows the striking train to be turned off without causing damage to the movement.
Suspension The piece on that a pendulum hangs, usually a spring but in some older clocks a piece of thread is used.
Sweep Seconds See Center Seconds.
Timepiece A clock that neither chimes nor strikes.
Ting-Tang A striking clock that sounds the quarters on two tone gongs or bells.
Train The wheels and pinions of a clock, the 'going' train keeps the time, also 'striking' & 'chiming' trains are used in more complicated clocks.
Verge An early type of escapement, technically the shaft on to that the pallet faces are fitted.
Warning A few minutes before the hour many striking mechanisms lift a warning piece that lifts the rack hook, allowing the rack to fall on to the snail and letting the strike train to run, until the pin on the warning wheel is stopped by the warning piece, at the hour the warning lever drops of the lifting pin on the minute wheel and allows the striking train to run.
Weights The weights provide the power for the trains of a clock often made of lead sometimes encased in brass or cast iron.
Wheel Circular piece with teeth cut around its circumference fitted on to an arbor these make up the train of a clock.