SEIKO (SII) NH37/NH39 Fourth Wheel And Pinion #0144185

Product Description

The SEIKO (SII) NH37/NH39 Fourth Wheel And Pinion (#0144185) is a genuine Japanese-made component for the NH37 and NH39 automatic movements . As part of the gear train, the fourth wheel transmits power from the movement’s center wheel to the escape wheel, playing a critical role in accurate timekeeping . This wheel includes the pinion as an integrated assembly, ensuring proper fit and reliable performance. This brand new original part is essential for watchmakers restoring proper power transmission and timekeeping accuracy when the original fourth wheel becomes worn or damaged.

Features & Function

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

• Gear train component – transmits power from the center wheel to the escape wheel for accurate timekeeping

• Integrated pinion design – includes pinion as a single assembly for precise fit

• Essential for service – commonly replaced during movement overhaul when gear train wear is detected

Specifications

• Part Number: 0144185

• Compatible Movements: Seiko NH37, NH39

• Movement Family: NH Series (based on NH35 architecture) 

• Movement Frequency: 21,600 vph (3 Hz) 

• Jewels: 24 

• Power Reserve: ~41 hours 

• Origin: Japan

Applications

• Service and overhaul – replacing worn or damaged fourth wheels in NH37/NH39 movements

• Gear train restoration – ensuring stable power transmission from the center wheel to the escapement

• 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 NH37 and NH39 are manufactured by Seiko Instruments Inc. (SII) and distributed by Time Module Inc. (TMI) .

2. Which movements is this fourth wheel compatible with?

This fourth wheel is compatible with Seiko NH37 and NH39 movements. The NH37 features a 24-hour subdial with date, while the NH39 adds an open-heart balance display . Both share the same gear train architecture.

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

Common signs include irregular timekeeping, low amplitude, or visible wear/damage to the teeth or pinion 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.