Shock resistant is a common mark stamped on the back of wrist
watch
A watch is a portable timepiece intended to be carried or worn by a person. It is designed to keep a consistent movement despite the motions caused by the person's activities. A wristwatch is designed to be worn around the wrist, attached b ...
es to indicate how well a watch copes with mechanical shocks. In a
mechanical watch
A mechanical watch is a watch that uses a clockwork mechanism to measure the passage of time, as opposed to quartz watches which function using the vibration modes of a piezoelectric quartz tuning fork, or radio watches, which are quartz wat ...
, it indicates that the delicate pivots that hold the
balance wheel
A balance wheel, or balance, is the timekeeping device used in mechanical watches and small clocks, analogous to the pendulum in a pendulum clock. It is a weighted wheel that rotates back and forth, being returned toward its center position by a ...
are mounted in a spring suspension system intended to protect them from damage if the watch is dropped. One of the earliest and most widely used was the
Incabloc system, invented in 1934. Before the widespread adoption of shock-resistant balance pivots in the 1950s, broken balance wheel staffs were a common cause of watch repairs.
Usage
Virtually all mechanical watches produced today are shock resistant. Even divers' watches (according to
ISO 6425) must correspond not only with such criteria as
water resistance,
luminosity, magnetic resistance and strap solidity, but also shock resistance.
ISO 1413 shock-resistant standard
The
International Organization for Standardization
The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Art ...
issued a standard for shock-resistant watches, which many countries have adopted. ISO 1413 Horology—Shock-resistant watches specifies the minimum requirements and describes the corresponding method of test. It is intended to allow homologation tests rather than the individual control of all watches of a production batch. It is based on the simulation of the shock received by a watch on falling accidentally from a height of 1 m on to a horizontal hardwood surface.
In practice shock resistance is generally tested by applying two shocks (one on the 9 o'clock side, and one to the crystal and perpendicular to the face). The shock is usually delivered by a hard plastic hammer mounted as a pendulum, so as to deliver a measured amount of energy, specifically, a 3 kg hammer with an impact velocity of 4.43 m/s (This will deliver approximately 3.7 Joules of energy to the watch). The peak acceleration delivered to the watch head is 3100g +/- 15%, in sinusoidal form, over 350 microseconds. After the first shock the displacement of the hands (started from 'noon' must be < 5mins). After the second shock, the watch must keep its accuracy to +/- 60 seconds/day after these two shocks as compared to before the test. A third shock is then applied onto the crown side. Nothing should be bent or broken. There is also a 'free-fall' test for the complete watch. First it is dropped crown up clasp open. Second, it is dropped on it case back. In the case of deployant clasps, they are opened but continuous under the watch. In both cases a trap door is used to drop the watch onto a surface calibrated to deliver the same shock profile as in the impact tests above. No components should be broken or lost in the free-fall tests.
See also
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Watch
A watch is a portable timepiece intended to be carried or worn by a person. It is designed to keep a consistent movement despite the motions caused by the person's activities. A wristwatch is designed to be worn around the wrist, attached b ...
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Diving watch
A diving watch, also commonly referred to as a diver's or dive watch, is a watch designed for underwater diving that features, as a minimum, a water resistance greater than , the equivalent of . The typical diver's watch will have a water resis ...
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Magnetic-resistant watch
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Water-resistant watch
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Incabloc shock protection system
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G-Shock
The G-Shock is a line of watches manufactured by the Japanese electronics company Casio, designed to resist mechanical stress, shock and vibration. G-Shock is an abbreviation for ''Gravitational Shock''. The watches in the G-Shock line are desi ...
References
ISO 1413:1984 Horology – Shock-resistant watches
External links
{{ISO standards
Watches