SEIKO (SII) NH35/NH36/NH37/NH38/NH39 Ratchet Wheel #0285051

Product Description

The SEIKO (SII) NH35/NH36/NH37/NH38/NH39 Ratchet Wheel (#0285051) is a genuine Japanese-made component for the popular NH series automatic movements. As a key part of the winding mechanism, the ratchet wheel interacts with the winding stem and the Magic Lever system to wind the mainspring, storing the energy that powers the watch. This brand new original part is essential for watchmakers restoring proper manual and automatic winding function when the original ratchet wheel becomes worn or damaged.

Features & Function

• Genuine Seiko/SII part – authentic Japanese-made component for NH35, NH36, NH37, NH38, and NH39 movements

• Winding mechanism component – works with the winding stem and Magic Lever system to wind the mainspring

• NH family compatibility – compatible across the most popular NH series calibers

• Direct replacement – drop-in replacement for worn or damaged ratchet wheels

Specifications

• Part Number: 0285051

• Compatible Movements: Seiko NH35, NH36, NH37, NH38, NH39 (also known as 4R35/36/37/38/39)

• Movement Family: NH Series (Basic Mechanical Series)

• Movement Diameter: 27.4 mm

• Movement Height: 5.32 mm

• Jewels: 24

• Beat Rate: 21,600 vph (3 Hz)

• Power Reserve: >41 hours

• Accuracy: -20 to +40 seconds/day (factory spec)

• Winding System: Bi-directional (Magic Lever)

• Origin: Japan

Applications

• Service and overhaul – replacing worn or damaged ratchet wheels in NH series movements

• Winding mechanism repair – resolving issues with manual or automatic winding efficiency

• Power reserve restoration – ensuring proper energy storage for reliable timekeeping

• Suitable for professional watchmakers and experienced repair technicians

FAQs

1. Is this a genuine Seiko/SII part?

Yes, this is a genuine Seiko (SII/TMI) factory part made in Japan. The NH series is manufactured by Seiko Instruments Inc. (SII) and distributed by Time Module Inc. (TMI).

2. Which movements is this ratchet wheel compatible with?

This ratchet wheel is compatible with Seiko NH35, NH36, NH37, NH38, and NH39 movements. The differences between these calibers are mainly related to complications (date, day-date, 24-hour indicator, open heart), but the winding mechanism architecture is shared across them.

3. What are the signs that the ratchet wheel needs replacement?

Common signs include reduced manual winding efficiency, poor power reserve, grinding or resistance when winding the crown, or visible wear/damage to the teeth during movement inspection. A qualified watchmaker can diagnose these issues during servicing.

Why Choose SOFLY Watch Parts?

• Fast worldwide shipping within 3 business days.

• Competitive pricing on Seiko/Hattori calibers.

• 3,000+ watch movements and parts in stock.

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• Personalized sourcing support via [email protected] or WhatsApp +86 18620212114.