Mechanical watch
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A mechanical watch is a watch that uses a non-electric mechanism to measure the passage of time. They are driven by a spring (called a mainspring) which must be wound periodically, and releases the energy to turn the clock's wheels as it unwinds. They keep time with a balance wheel, which oscillates back and forth at a constant rate, and make a 'ticking' sound when operating. Mechanical watches evolved in Europe in the 1600s from spring powered clocks, which appeared in the 1400s.
Mechanical watches are not as accurate as modern quartz watches and are generally more expensive. They are now kept more for their aesthetic qualities and as jewelry than for their timekeeping ability.
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[edit] Mechanism
All mechanical watches have these five parts:
- A mainspring that stores mechanical energy to power the watch.
- A gear train, which has the dual function of transmitting the force of the mainspring to the balance wheel, and adding up the swings of the balance wheel to get units of seconds, minutes and hours, etc. A separate part of the gear train allows the user to wind the mainspring and enables the hands to be moved to set the time.
- A balance wheel which oscillates back and forth. Each swing of the balance wheel takes precisely the same amount of time. This is the timekeeping element in the watch.
- An escapement mechanism which has the dual function of keeping the balance wheel vibrating by giving it an impulse each swing, and allowing the clock's gears to advance or 'escape' by a set amount with each swing. It is this part that produces the characteristic 'ticking' sound of the mechanical watch.
- An indicating dial, usually a traditional clock face with rotating hands, to display the time in human-readable form.
Additional functions on a watch besides the basic timekeeping ones are traditionally called complications. Mechanical watches may have these complications:
- Automatic winding or self-winding - in order to relieve the need to wind the watch, this device winds the watch's mainspring automatically using the natural motions of the wrist, with a rotating weight mechanism.
- Calendar - displays the date, and often weekday, month, and year. Simple calendar watches don't account for the different lengths of the months, requiring the user to reset the date 5 times a year, but perpetual calendar watches account for this, and even leap years.[1]
- Alarm - a bell or buzzer that can be set to go off at a given time.
- Chronograph - a watch with additional stopwatch functions. Buttons on the case start and stop the second hand and reset it to zero, and usually several subdials display the elapsed time in larger units.
- Hacking feature - found on military watches, a mechanism that stops the second hand while the watch is being set. This enables watches to be synchronized to the precise second.
- Moon phase dial - shows the phase of the moon with a moon face on a rotating disk.
- Wind indicator or power reserve indicator - mostly found on automatic watches, a subdial that shows how much power is left in the mainspring, usually in terms of hours left to run.
- Repeater - a watch that chimes the hours audibly at the press of a button. This rare complication was used before artificial lighting to check what time it was in the dark.
- Tourbillon - this expensive feature was originally designed to make the watch more accurate. In an ordinary watch the balance wheel oscillates at different rates when the watch is in different positions, causing inaccuracy. In a tourbillon, the balance wheel is mounted in a rotating cage so it will experience all positions equally. The mechanism is usually exposed on the face to show it off.
[edit] History
Mechanical watches were very popular back from early on, especially from around 1760, when the chronometer was created by John Harrison, and therefore "perfecting" the movement of the watch industry. Watches from the early 1500s to the early 1800s featured the chain-driven fusee movement, which was the only means for substitution of a mainspring format back in the time. The fusees were very brittle, were very easy to break, and often featured many, many problems, especially inaccuracy of timekeeping when the fusee chain became loose or lost its velocity after the lack of maintenance.
Mainsprings began to become popular as technological stepping stones improved, and newer designs came to place in the industry, perfecting the movement of a typical mechanical watch. With the new mainspring, the fusee maintenance and chain-loosening problems were now gone, a mainspring-operated watch does not have to be serviced as much as the fusee, and also other time-keeping problems were solved with the evolution of the Mainspring. Mainspring watches were most popular from the 1850s to the 1970s before the evolution of the Quartz Digital operation method came into place.
Basically three types of escapements have been industrially used: "lever", "pin-lever", and "Roskopf", latter invented by Georges Frederic Roskopf for cheaper watches.
As manual-wound mechanical watches became less popular and less favored in the 1960s, watch design and industrialists came out with the Automatic Watch Movement. Whereas a mechanically-wound watch must be wound with the pendant or a levered setting, an Automatic watch does not require to be wound by the pendant, but by simply shaking the watch winds the watch automatically. The interior of an Automatic Watch houses a swivelling metal or brass "plate", that swivels on its axes when the watch is shaken horizontally. An Automatic watch may come in handy if you do not want to constantly wind a watch manually, because it simply winds itself from its position on your wrist or your arm.
But since the mainspring does not have an even power output from low wound to fully wound sequences, several solutions were tried to rectify this problem. Such as the chain and fusee (the barrel for the mainspring has a chain attached to one end which then on the other end is fixed to the fusee) were used to correct the power output. This evens the power from the mainspring out to some degree.
