Old Passion's Clock Dictionary
A series of flat springs, attributed to Joseph Ives of Bristol, Connecticut, used instead of a coil spring to power a clock movement.
A clock designed to hang on a wall.
A projection on the lifting piece of a striking clock which intercepts a pin in the warning wheel and holds the striking train ready until the exact hour of striking.
Usually the penultimate wheel in a striking train, carrying a pin which locks the striking train after release, until the lifting piece falls at the hour and the clock strikes.
A clock that uses heavy objects suspended from the works by chain or spring to power the clock movement as they drop. A spring-driven clock, on the other hand, relies on the tension of a coiled wire to provide power.
The best clocks have brass-cased driving weights. Clock weight design may be used as a guide to the date of manufacture of a clock. However, dealers and repairers frequently interchanged weights between clocks, brass weights being used to improve a clock, or a heavier weight being substituted for the original to make the clock go.
Cast iron was first available commercially towards the end of the 18th century, and it soon became cheaper than lead. Its use for clock weights became almost universal in the 19th century. The original lead or brass-cased weights on early clocks have often been lost and replaced by cast-iron weights.
The earliest weight-driven clocks probably had stones as weights. Lead is perhaps the best material. It is easily worked, is reasonably cheap, and has a high density, which permits smaller driving weights occupying less space in the clock case.
The weights of early turret clocks were of stone, pear-shaped with rough edges smoothed off. A bolt was let into the top, sometimes run in with lead. Many stone weights are still in use, often supplemented by miscellaneous cast-iron pieces of a later era.
Until the 18th century lead, being a great deal cheaper than iron, was commonly used, beaten or cast into a roughly cylindrical form around an eye bolt. When iron castings became available, weights were made like flat cylindrical cheeses, with a hole in the middle and a slot so that they could be slipped over an eye bolt, and as many as required could be added. Box-shaped weights were also used, with an aperture for adding extra weights.
In the early days turret-clock lines were of rope, half an inch or more in diameter. Later, steel wire was introduced; owing to its greater strength and smaller diameter, far more turns could be accommodated on the barrel. Recently, very strong plastic line has become available. This is much softer, and kinder to elderly barrels.
A method, found only in very high-quality work, of supporting clock pivots on smooth wheels to reduce friction.
A large grooved wheel fitted with a handle and mounted on a bracket or stand, fixed to the workbench in a suitable position for driving turning tools or lathes by means of an endless cord. The bench wheel remains fixed in one place while the turning tools are vice-held. The bench-wheel bracket usually has a sliding adjustment for tensioning the cord.
A gear wheel with teeth cut at an angle and meshing with a similar wheel to drive an arbor at any angle up to 90º. Bevel gearing is seldom found in ordinary clockwork, the main horological application being in the leading-off work in turret clocks.
A wheel cut with teeth on one face which mesh with a pinion at 90º, used in verge clocks to drive the vertical escape pinion. The contrate wheel is also found in platform-escapement carriage clocks, again driving the escape pinion.
The verge escape wheel, so named because of its resemblance to a crown.
The final wheel in the going train of a clock. The escape wheel interacts directly with the clock escapement.
The foot wheel, like the bench wheel, is used to drive a lathe or other machine, but it is much larger. It is mounted below the bench and rotated by means of a foot-operated, pivoted treadle. A stepped foot wheel has two or more diameters of cord groove so that the speed ratio between the wheel and the machine it is driving can be changed, and some foot wheels are made sufficiently out of balance for the wheel always to come to rest in a suitable position for starting again by downward pressure on the treadle. An intermediate pulley, jockey pulley or countershaft can be used between the foot wheel and the machine.
The hand wheel is like a bench wheel except that its bracket is fixed directly to the frame of the lathe or machine it is driving instead of to the bench. The Swiss mandril and some other tools have the hand wheel geared directly to the spindle of the machine, and for many purposes the hand wheel has an advantage over the bow in that it imparts continuous motion in one direction.
A wheel cut with teeth like a saw and used in conjunction with a click or pawl to make rotation possible in one direction only.
A tool which imparts a reciprocating or backwards and forwards motion to a pinion, or a tool for polishing a pivot or pinion leaves. In the pivot-polishing version of this tool the polisher, which is either a burnisher or soft-metal polisher charged with a polishing compound, is worked to and fro, while at the same time a rotary motion is imparted to the pivot. For polishing pinion leaves, the pinion is moved axially back and forth over a charged polisher which can be a rotating disc.
A mechanism for winding a clock automatically at regular intervals. Large turret clocks require a great deal of effort to wind manually, and are increasingly being converted to automatic winding. In one common type, a continuous loop of bicycle chain passes round a sprocket on the clock barrel or other convenient arbor, thence round a pulley carrying the driving weight, and then over a sprocket driven by the electric motor. The remainder of the loop is carried out of the way by pulleys and kept taut by a counterweight. The clock is driven by the gradually falling weight which, when it reaches a lower limit, actuates a switch starting the electric motor, which hauls in the chain on the other side of the main weight. The switch cuts out when the weight reaches the upper limit. This system closely resembles Christiaan Huygens's winding mechanism so often seen on 30-hour clocks, and is called by that name.
In another system, a mechanical epicyclic differential is used. In this case, one connection to the differential drives the clock through a roller chain, and the other two connect with a weight drum and the electric motor respectively. A third type incorporates the electric motor with the weight. It climbs the chain, which passes as a loop over the barrel or other arbor of the clock. The motor may be a synchronous type, which climbs the chain at the same rate as the clock lets it out. Some clockmakers couple electric motors directly to the striking and chiming trains, disconnect the escapement, and use a synchronous motor to drive the hands. Much damage has been done in this way. Turret clocks rewound by hydraulic power are also known.
Mechanical domestic clocks, with their more modest power requirements, are rarely wound automatically, although some 30-hour clocks have been converted to automatic winding to avoid this daily chore. The Atmos clock, whihc utilizes atmospheric changes in pressure and temperature to provide winding energy, is a novel domestic automatic-winding clock.
The tool for winding a clock. Crank keys are best suited for weight clocks and eight-day fusee clocks, while the plate key is best suited to going-barrel spring clocks and clocks requiring a high winding torque.
Thirty-hour longcase clocks are usually arranged for pull winding on Christiaan Huygens's system. The length of rope or chain between the smaller weight and the ratchet wheel is pulled down, thus raising the driving weight without stopping the clock.
An iron statue clock with blinking eyes.
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