Escapement

detent escapementCross-beat escapementduplex escapementsspring detent escapementacted as a large gearclock escapement mechanismdeadbeat escapementdouble comma escapementescapement with constant forceescapements
An escapement is a device in mechanical watches and clocks that transfers energy to the timekeeping element (the "impulse action") and allows the number of its oscillations to be counted (the "locking action").wikipedia
209 Related Articles

Mechanical watch

mechanicalmechanical watchesmanual winding
An escapement is a device in mechanical watches and clocks that transfers energy to the timekeeping element (the "impulse action") and allows the number of its oscillations to be counted (the "locking action").
A device called an escapement releases the watch's wheels to move forward a small amount with each swing of the balance wheel, moving the watch's hands forward at a constant rate.

Balance wheel

foliotcompensation balanceauxiliary temperature compensation
The impulse action transfers energy to the clock's timekeeping element (usually a pendulum or balance wheel) to replace the energy lost to friction during its cycle and keep the timekeeper oscillating.
It is driven by the escapement, which transforms the rotating motion of the watch gear train into impulses delivered to the balance wheel.

Water clock

clepsydrawater clockswater-clock
The invention of the first all-mechanical escapement, the verge escapement, in 13th-century Europe initiated a change in timekeeping methods from continuous processes, such as the flow of water in water clocks, to repetitive oscillatory processes, such as the swing of pendulums, which could yield more accuracy.
The Greeks and Romans advanced water clock design to include the inflow clepsydra with an early feedback system, gearing, and escapement mechanism, which were connected to fanciful automata and resulted in improved accuracy.

Clock

clockstimepiecemechanical clock
An escapement is a device in mechanical watches and clocks that transfers energy to the timekeeping element (the "impulse action") and allows the number of its oscillations to be counted (the "locking action"). The importance of the escapement in the history of technology is that it was the key invention that made the all-mechanical clock possible.
This is not considered an escapement mechanism clock as it was unidirectional, the Song dynasty polymath and genius Su Song (1020–1101) incorporated it into his monumental innovation of the astronomical clock-tower of Kaifeng in 1088.

Pendulum

pendulumssimple pendulumpendula
The impulse action transfers energy to the clock's timekeeping element (usually a pendulum or balance wheel) to replace the energy lost to friction during its cycle and keep the timekeeper oscillating. The invention of the first all-mechanical escapement, the verge escapement, in 13th-century Europe initiated a change in timekeeping methods from continuous processes, such as the flow of water in water clocks, to repetitive oscillatory processes, such as the swing of pendulums, which could yield more accuracy.
The crutch is pushed back and forth by the clock's escapement, (g,h) .

Yi Xing

Xing, Yi
In China, the Tang dynasty Buddhist monk Yi Xing along with government official Liang Lingzan made the escapement in 723 (or 725) to the workings of a water-powered armillary sphere and clock drive.
His astronomical celestial globe featured a clockwork escapement mechanism, the first in a long tradition of Chinese astronomical clockworks.

Astronomical clock

astronomicalastronomical clock towerastronomical clock towers
late 10th century) and Su Song (1020–1101) duly applied escapement devices for their astronomical clock towers, before the technology stagnated and retrogressed.
Su Song is noted for having incorporated an escapement mechanism and earliest known endless power-transmitting chain drive for his clock-tower and armillary sphere to function.

Su Song

Song, SuSu
late 10th century) and Su Song (1020–1101) duly applied escapement devices for their astronomical clock towers, before the technology stagnated and retrogressed.
Su Song was the engineer of a hydro-mechanical astronomical clock tower in medieval Kaifeng, which employed the use of an early escapement mechanism.

History of technology

historian of technologytechnologytechnological growth
The importance of the escapement in the history of technology is that it was the key invention that made the all-mechanical clock possible.
In time-keeping, the introduction of the inflow clepsydra and its mechanization by the dial and pointer, the application of a feedback system and the escapement mechanism far superseded the earlier outflow clepsydra.

Verge escapement

verge and foliotfoliotcrown wheel and verge escapement
The invention of the first all-mechanical escapement, the verge escapement, in 13th-century Europe initiated a change in timekeeping methods from continuous processes, such as the flow of water in water clocks, to repetitive oscillatory processes, such as the swing of pendulums, which could yield more accuracy.
The verge (or crown wheel) escapement is the earliest known type of mechanical escapement, the mechanism in a mechanical clock that controls its rate by allowing the gear train to advance at regular intervals or 'ticks'.

Armillary sphere

armillaryspherical astrolabearmilla
In China, the Tang dynasty Buddhist monk Yi Xing along with government official Liang Lingzan made the escapement in 723 (or 725) to the workings of a water-powered armillary sphere and clock drive.
In 723 AD, Yi Xing and government official Liang Ling-zan combined Zhang Heng's water powered celestial globe with an escapement device.

Washstand

washbasins
The earliest liquid-driven escapement was described by the Greek engineer Philo of Byzantium (3rd century BC) in his technical treatise Pneumatics (chapter 31) as part of a washstand.
In his Pneumatics, (chapter 31) Philo of Byzantium, a Greek engineer and writer on mechanics, describes an escapement mechanism, the earliest known, as part of a washstand.

Grasshopper escapement

Some escapements avoid sliding friction; examples include the grasshopper escapement of John Harrison in the 18th century, This may avoid the need for lubrication in the escapement (though it does not obviate the requirement for lubrication of other parts of the gear train).
The grasshopper escapement is a low-friction escapement for pendulum clocks invented by British clockmaker John Harrison around 1722.

Coaxial escapement

co-axial escapement
Coaxial escapement, invented by English watchmaker George Daniels around 1974 and patented in 1980 has rather dramatically increased the accuracy and durability of mechanical watches.
The coaxial escapement is a type of modern watch escapement mechanism invented by English watchmaker George Daniels.

Zhang Sixun

Song dynasty (960–1279) horologists Zhang Sixun (fl.
The liquid mercury filled scoops of the waterwheel would rotate and thus provide the effect of an escapement mechanism in clockworks and allow the astronomical armillary sphere to rotate as needed.

Clockwork

clockwork motorclockworksClockwork Doll
Historically, a liquid-driven escapement was used for a washstand design in ancient Greece and the Hellenistic world, particularly Ptolemaic Egypt, while liquid-driven escapements were applied to clockworks beginning in Tang dynasty China and culminating during the Song dynasty.
Often power for the device is stored within it, via a winding device that applies mechanical stress to an energy-storage mechanism such as a mainspring, thus involving some form of escapement; in other cases, hand power may be utilized.

Tourbillon

tourbillion
The tourbillon was invented to minimize this: the balance and spring is put in a cage which rotates (typically but not necessarily, once a minute), smoothing gravitational distortions.
In horology, a tourbillon ( "whirlwind") is an addition to the mechanics of a watch escapement.

Song dynasty

SongSouthern SongNorthern Song dynasty
Song dynasty (960–1279) horologists Zhang Sixun (fl. Historically, a liquid-driven escapement was used for a washstand design in ancient Greece and the Hellenistic world, particularly Ptolemaic Egypt, while liquid-driven escapements were applied to clockworks beginning in Tang dynasty China and culminating during the Song dynasty.
The clock tower featured large astronomical instruments of the armillary sphere and celestial globe, both driven by an early intermittently working escapement mechanism (similarly to the western verge escapement of true mechanical clocks appeared in medieval clockworks, derived from ancient clockworks of classical times).

Tang dynasty

TangTang ChinaTang Empire
In China, the Tang dynasty Buddhist monk Yi Xing along with government official Liang Lingzan made the escapement in 723 (or 725) to the workings of a water-powered armillary sphere and clock drive. Historically, a liquid-driven escapement was used for a washstand design in ancient Greece and the Hellenistic world, particularly Ptolemaic Egypt, while liquid-driven escapements were applied to clockworks beginning in Tang dynasty China and culminating during the Song dynasty.
3rd century), which gave the Tang engineer, astronomer, and monk Yi Xing (683–727) inspiration when he invented the world's first clockwork escapement mechanism in 725.

Spring Drive

Seiko Spring DriveSpring drive watch
Yoshikazu Akahane with teams of engineers at Seiko Epson developed the spring drive movement around 1977, and obtained not less than 230 patents between 1982 and the present.
The conventional escapement is replaced with a device that Seiko calls a Tri-synchro Regulator to regulate the unwinding of the mainspring.

Anchor escapement

deadbeat escapementdeadbeatpocket watch
These problems were eliminated in the deadbeat escapement, which slowly replaced the anchor in precision clocks.
In horology, the anchor escapement is a type of escapement used in pendulum clocks.

Philo of Byzantium

Philo
The earliest liquid-driven escapement was described by the Greek engineer Philo of Byzantium (3rd century BC) in his technical treatise Pneumatics (chapter 31) as part of a washstand.
In his Pneumatics (chapter 31) Philo describes an escapement mechanism, the earliest known, as part of a washstand.

John Harrison

H-4H4H4 and H5
Some escapements avoid sliding friction; examples include the grasshopper escapement of John Harrison in the 18th century, This may avoid the need for lubrication in the escapement (though it does not obviate the requirement for lubrication of other parts of the gear train).
In the 1720s, the English clockmaker Henry Sully invented a marine clock that was designed to determine longitude: this was in the form of a clock with a large balance wheel that was vertically mounted on friction rollers and impulsed by a frictional rest Debaufre type escapement.

George Daniels (watchmaker)

George DanielsDr. George Daniels, MBE
Coaxial escapement, invented by English watchmaker George Daniels around 1974 and patented in 1980 has rather dramatically increased the accuracy and durability of mechanical watches.
After much experimentation, Daniels had designed a new type of watch escapement by 1974.

Lever escapement

escapement wheellever watchSilicon escapement wheel
Therefore, the self-starting lever escapement became dominant in watches.
The lever escapement, invented by British clockmaker Thomas Mudge in 1755, is a type of escapement that is used in almost all mechanical watches, as well as small mechanical non-pendulum clocks, alarm clocks, and kitchen timers.