Seiko 2118A - Parts List
Seiko 2118A – Technical Guide (High Quality)
The Seiko 2118A is a manual-winding mechanical movement introduced in the late 1960s, crafted primarily for ladies’ wristwatches. This compact caliber features a precise two-hand configuration (hour and minute) and is designed to fit slim, elegant watch cases while providing reliable performance and durability. The 2118A highlights Seiko’s expertise in producing small, efficient movements tailored to women’s timepieces.
1. Technical Specifications
| Feature | Details |
|---|---|
| Caliber Number | Seiko 2118A |
| Movement Type | Mechanical – Manual winding |
| Functions | Hour, Minute |
| Jewels | 17 |
| Beat Rate | 18,000 vibrations/hour (5 beats per second) |
| Power Reserve | Approximately 40 hours |
| Winding Method | Manual only |
| Hacking Seconds | No |
| Calendar | None |
| Diameter | Approximately 19 mm |
| Movement Height | Approximately 3.5 mm |
| Shock Protection | Diashock (balance staff) |
2. Key Features
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Two-hand display focusing on hour and minute functions
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Slim and compact design ideal for delicate ladies’ watches
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17-jewel construction ensuring reduced friction and enhanced durability
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Diashock balance protection for impact resistance
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Reliable manual winding with smooth operation
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Service-friendly construction facilitating maintenance
3. Operating Instructions
Manual Winding:
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Wind the crown clockwise daily until resistance is felt; avoid overwinding
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Power reserve lasts approximately 40 hours
Time Setting:
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Pull the crown out to the setting position
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Rotate to adjust hour and minute hands
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Push crown back in to resume normal operation
4. Movement Architecture
Dial Side:
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Hour and minute wheels with cannon pinion
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Keyless works with sliding pinion and clutch wheel for time setting
Train Side:
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Mainspring barrel with ratchet and click springs
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Gear train including center, third, and escape wheels
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Pallet fork and balance wheel assembly with flat hairspring
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Regulator lever for precise timing adjustment
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Diashock system protecting balance pivots
5. Service Recommendations
| Service Interval | Every 4–6 years |
|---|---|
| Cleaning | Complete disassembly and ultrasonic cleaning |
| Lubrication | Train pivots, escapement, balance jewels |
| Regulation | Adjust via regulator lever aiming for ±30 seconds/day |
6. Common Issues & Troubleshooting
| Issue | Likely Cause | Solution |
|---|---|---|
| Watch stops prematurely | Dried or dirty mainspring | Clean and lubricate; replace mainspring if necessary |
| Inaccurate timekeeping | Magnetized or dirty balance pivots | Demagnetize and clean pivots |
| Loose or slipping hands | Worn cannon pinion | Refit or replace cannon pinion |
| Low amplitude | Dirty jewels or weak mainspring | Service movement and replace parts if necessary |
7. Applications
The Seiko 2118A was installed in:
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Ladies’ wristwatches with slim, elegant cases (typically 18–22 mm diameter)
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Polished steel or gold-plated cases
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Watches featuring minimalist dials without seconds or date complications
8. Historical Context
The 2118A represents Seiko’s continued dedication in the late 1960s to:
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Manufacturing compact, reliable mechanical calibers for ladies’ watches
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Combining slim form factors with robust mechanical design
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Building a foundation for future advancements in watch movement technology
9. Conclusion
The Seiko 2118A is a reliable and elegant manual-winding movement designed for vintage ladies’ wristwatches. Its simple two-hand layout, slim profile, and durable construction make it a favored caliber among collectors and restorers. With proper servicing, the 2118A offers dependable and graceful timekeeping that showcases Seiko’s craftsmanship during its era.
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