The Seiko NH35 and 4R36 calibres wind in both directions, at a rate of 650 to 800 turns per day.
| Rotation direction | Bidirectional |
| Turns per day | 650 to 800 |
| Power reserve | Approx. 41 hours |
| Special feature | Can be hand-wound |
The Magic Lever
Since 1959 Seiko has used a winding system called the Magic Lever, which converts the rotation of the oscillating weight in both directions into useful motion. It is a remarkably simple device (two pawls and a lever), and it is why these calibres wind bidirectionally with unusual efficiency.
In practice, an NH35 recharges quickly. A setting of 650 turns per day is enough in the vast majority of cases.
NH35, 4R35, 4R36: what is the difference?
They are the same movement under three names. The NH35 is the version sold by Seiko Instruments to other brands; it is found in many micro-brand watches. The 4R35 is Seiko's in-house reference. The 4R36 adds a day display.
The winder setting is identical for all three.
A useful feature
Unlike many automatics, these calibres can be hand-wound via the crown and have a hacking seconds function. You can therefore start the watch by hand before placing it on the winder, which we recommend: around twenty turns of the crown, then set the time, then place it on the winder.
A winder alone takes several hours to wind an empty barrel. This simple step saves you the wait.
The accuracy of these movements
The NH35 is rated at between -20 and +40 seconds per day, a wide tolerance that is normal for a calibre at this price. Many examples do much better once regulated.
A winder does not change a watch's accuracy. However, a movement kept running continuously reveals its real drift, which you cannot observe on a watch that is regularly stopped and reset.
Other calibres
See our Settings by calibre page, or our watch winders.
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