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Below is a glossary of clock terms if you
cannot find the term you are looking for please contact me
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| Underlined Links in this column are cross references to other entries | |
| Anchor | Type of pallet used in escapements of clocks & watches shaped like a ships anchor |
| Arbor | Spindle or axle on which clock wheels are mounted see also Barrel Arbor |
| Back Cock | Small plate mounted on back plate of clock in which the pallet pivots |
| Back Plate | The plate in which the movements back pivots run (the back plate is that which is furthest from the dial) |
| Balance | Oscillating part usually a wheel which controls the timekeeping of clocks & watches |
| Barrel | Cylindrical part which in spring driven clocks holds the mainspring and in weight driven clocks has the lines wrapped around it |
| Barrel Arbor | Spindle with a hook which catches the mainspring and has a square 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 which is moved up or down in order to regulate the clock |
| Brocot Escapement | Type of dead beat escapement used in many French clocks using semi circular pins in the pallets |
| Bush | A replacement bearing used to repair worn pivot holes |
| Cannon Pinion | Pinion which holds the minute hand usually a friction fit over the centre wheel or loose over centre 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 |
| Centre Wheel | Wheel on which the cannon pinion is fitted usually next to the barrel or great wheel depending on the type of clock |
| Centre Seconds | A seconds hand fitted to an arbor pivoted at the centre of the dial usually at the same point as the hour and minute hands |
| Chapter Ring | Circle on a dial which carries the markings for the hour and minutes |
| Chiming Clock | Clock which sounds a tune at each quarter of an hour such westminster,whittington etc. |
| Chronometer | Clock or watch often used on board ship which gives excellent timekeeping |
| Click | Ratchet or pawl used to prevent the mainspring or weight unwinding when wound held in position by the clickspring |
| Cock | Bracket or small plate attached to larger plate to hold parts which are fitted outside the main plates of the clock |
| Collet | 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 12 slots at different spacings used to stop the strike train after striking the appropriate number |
| 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 which positions and holds another part in position |
| Dial | The visible 'face' of the clock on which the numerals or chapter ring are situated and from which 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 which the clock will run on one winding |
| Escape Wheel | Wheel which transmits power through the pallets to the pendulum |
| Escapement | Term used for the type of parts that transmit power to the pendulum or other device which regulates timekeeping. Such as verge, anchor, dead beat and platform escapements |
| False Pendulum | See Dummy Pendulum |
| 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 |
| Friction Washer | Spring washer, used mainly in english clocks to connect the cannon pinion to the centre wheel whilst allowing the minute hand to be moved |
| Front Plate | The clocks main front plate positioned just under the dial |
| Fusee | Cone shaped part usually with grooves to accept a line 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 equalise 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 which 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 |
| 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 |
| Grande Sonnerie | Striking clock which strikes the last hour and the quarters at each quarter hour |
| Grandfather Clock | Common name given to Longcase 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 which expand different amounts keep the pendulum the same length |
| Hammer | Part which is lifted and then released to strike a gong or bell in a striking or chiming clock |
| Hands | The 'pointers' which 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 longcase clock which can be removed by pulling forward or sometimes upwards in early clocks |
| Hoop Wheel | Wheel in the striking train of a count wheel clock which a lever stops at the end of the striking |
| Hour Wheel | Wheel on to which the hour hand is fitted sometimes bearing on a seperate cock which holds it away from the cannon pinion over which it is fitted, it is driven by the minute wheel |
| Impulse | The period during which the escape wheel imparts power to the pallets |
| In Beat | See Beat |
| 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 which 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 |
| Lines | Lines made of gut or wire are used in both weight driven clocks and fusee clocks |
| Locking Plate | Another term for a count wheel |
| Longcase 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 which 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 which 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 clock plate intended to retain the oil at the pivot |
| Pallets | The part of the escapement which takes power from the escape wheel and delivers it to the pendulum via the crutch with each oscillation of the pendulum or balance |
| 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 which hold the plates together the correct distance apart |
| Pin Drum | A drum with pins protruding which lift hammers in a chiming or musical clock as the drum revolves |
| 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 which revolves in a hole in the plates |
| Plates | Flat metal or occasionally wooden pieces in between which the wheels and other internal parts are fitted |
| Platform Escapement | Consisting of a balance, pallets and escape wheel on a flat brass plate, these are most often found on french clocks in particular carriage clocks |
| Potance | Bracket or cock which carries the lower pivot of the crown wheel of a verge movement |
| Pull Repeat | A mechanism which when a cord is pulled repeats the last hour strike or quarters of a seperate chiming train |
| Pulley | Wheel around which the lines of a weight driven clock run halving the drop required but also halving the force imparted on the train |