Accuracy Of Mechanical Watches; Specifications - Seiko 8R48 Instructions

ACCURACY OF MECHANICAL WATCHES

The accuracy of mechanical watches is indicated by the daily rates of one week or
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so.
The accuracy of mechanical watches may not fall within the specified range of
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time accuracy because of loss/gain changes due to the conditions of use, such as
the length of time during which the watch is worn on the wrist, arm movement,
whether the mainspring is wound up fully or not, etc.
The key components in mechanical watches are made of metals which expand or
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contract depending on temperatures due to metal properties. This exerts an effect
on the accuracy of the watches. Mechanical watches tend to lose time at high
temperatures while they tend to gain time at low temperatures.
In order to improve accuracy, it is important to regularly supply energy to the balance
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that controls the speed of the gears. The driving force of the mainspring that powers
mechanical watches varies between when it is fully wound and immediately before
it is unwound. As the mainspring unwinds, the force weakens.
Relatively steady accuracy can be obtained by wearing the watch on the wrist
frequently for the self-winding type and winding up the mainspring fully everyday
at a fixed time to move it regularly for the wind-up mechanical type.
When affected by strong external magnetism, a mechanical watch may loss/gain
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time temporarily. The parts of the watch may become magnetized depending on
the extent of the effect. In such a case, consult the retailer from whom the watch
was purchased since the watch requires repair, including demagnetizing.
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SPECIFICATIONS

1 Display system
Time/Calendar ............................................. Hour, minute and small second hands
Stopwatch ................................................... Measures up to 12 hours
2 Vibrations per hour............................................. 28,800
3 Loss/gain (daily rate) ........................................... B e t w e e n +25 a n d -15 s e c o n d s a t n o r m a l
4 Continuous operating time ............................... More than approx. 45 hours
5 Driving system ................................................... Automatic winding type with manual winding
6 Number of jewels............................................... 34 jewels
• The accuracy above is factory adjusted.
• Due to the characteristics of mechanical watches, any actual daily rate may not fall within the range of
time accuracy specified above dependent on the conditions of use, such as the length of time during
which the watch is worn on the wrist, temperature, arm movement, and whether the mainspring is
wound up fully or not, etc.
Date is displayed in numerals
Stopwatch hour, Stopwatch minute and Stopwatch
second hands
temperature range (between 5 °C and 35 °C or
between 41 °F and 95 °F)
mechanism
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