Seiko 4R37A Quick start guide

PARTS LIST /TECHNICAL GUIDE

Movement size

 • Diameter 

Outside: Ø 27.4 mm

   Casing: Ø27.0mm

 • Height:   5.32mm

Automatic Cal. 4R37A

[SPECIFICATIONS]

Item Cal. No.

Loss/Gain

Dailyratewornon

thewristat

temperature range

between5°Cand

35°C)

Between+45and-35seconds

Standardratefor

measurement

Mainspringwind

upstatus Fullywindup After24hours

fromfullywindup

Testingpositions Dialupward:

T0(CH) 6o’clockatthetop 9o’clockatthetop Dualupward:

T24(CH)

Measurement

(dailyratein

seconds:s/d)

±20s/d ±30s/d ±30s/d

(Isochronism

fault:T24-T0)

±30s/d

Regulation system ETACHRONSystem

Lift angle of the escapement 53°

Power reserve Fromfullywoundtostoppage:Approximately40hours

Number of jewels 24jewels

4R37A

Movement size

Outsidediameter Ø 27.4 mm

Casingdiameter Ø27.0mm

Height 5.32mm

Driving system Automaticwindingwithmanualwindingmechanism

Time indication

• 3hands

(Hour,Minute,andSmallsecondhands)

• Dateindication

•24-hourindicator

Additional function •Datecorrectionfunction

•Secondhandstopfunction

Crown

operation

Normalposition Manualwinding(clockwiseonly)

1stclickposition Datesetting(counterclockwise)

2ndclickposition Timesetting(Hourandminute),Secondhandstop

Vibration per hour 21,600(5beatspersecond)

 • 3hands

  (hour,minuteandsecondhands)

 • Dateindication

 • 24-hourindicator

Cal. 4R37A

PARTS LIST

2/21

SEIKO Automatic Mechanical Cal. 4R37A is based on Cal. 4R35B.

This watch has a small 24-hour clock in the 10 o’clock direction.

FEATURES

CHARACTERISTICS OF A MECHANICAL WATCH

1. This mechanical watch operates using power obtained from a mainspring.

2. While loss/gain of a quartz watch is indicated by a monthly or annual rate, accuracy of a

mechanical watch is normally indicated by a daily rate (loss/gain per day).

3. Normal usage accuracy of a mechanical watch varies according to conditions of use (time

period that the watch is worn on the wrist, temperature environment, hand movement, and

winding state of the mainspring).

4. When the watch is affected by strong magnetism, it temporarily gains or loses time. If the

watch encounters a strong magnetic ﬁeld, the parts of the watch may be magnetized. In this

case, repairs such as removal of magnetism are required.

Cal. 4R37A

PARTS LIST

3/21

→Please refer to the following pages.



Lubricating: Types of oil Oil quantity

AO-3 (Moebius A) Liberal quantity

SEIKO Watch Oil S-6 Normal quantity

SEIKO Watch Oil S-4

Disassembling procedures Figs. : 153

Reassembling procedures Figs. : 53

[CALENDAR MECHANISM 1]

DATE DISK GUARD SCREW

0012 354

DATE DISK GUARD

0808 183

DATE DIAL

DATE JUMPER

0810 183

❷

③

❹

⑤

Cal. 4R37A

PARTS LIST

4/21

→Please refer to the following pages.



Lubricating: Types of oil

AO-3 (Moebius A)

SEIKO Watch Oil S-6

SEIKO Watch Oil S-4

[CALENDAR MECHANISM 2]

INTERMEDIATE WHEEL

FOR DATE SETTING E

0962 025

GUARD FOR DATE

CORRECTOR SETTING

TRANSMISSSION WHEEL

SCREW

0012 485

GUARD FOR DATE

CORRECTOR SETTING

TRANSMISSION WHEEL

0836 183

INTERMEDIATE WHEEL FOR

DATE SETTING C

0962 185

INTERMEDIATE WHEEL FOR

DATE SETTING B

0962 023

DATE SETTING WHEEL

0737 183

DIAL HOLDING SPACER

4408 ***

MINUTE WHEEL AND PINION

0261 183

INTERMEDIATE DATE

DRIVING WHEEL AND PINION

0817 300

24-HOUR WHEEL

0157 182

CANNON PINION

0225 417

⑮

HOUR WHEEL

0273 184

LOWER

SHOCK

ABSORBING

SPRING

LOWER SHOCK

ABSORBING CAP

JEWEL

LOWER HOLE JEWEL FRAME

FOR SHOCK-ABSORBER

⑩

⑫

⑨

⑭

⑯

⑰

24-1

0014 577

0011 220

0014 295

⑬

⑪

24-1

⑥

❼

⑧

Cal. 4R37A

PARTS LIST

5/21

→Please refer to the following pages.



Lubricating: Types of oil

AO-3 (Moebius A)

SEIKO Watch Oil S-6

SEIKO Watch Oil S-4

[BALANCE AND ESCAPEMENT]

OSCILLATING WEIGHT WITH BALL BEARING

Refer to SEIKO Web Parts Catalogue.

0509 ***

BALANCE BRIDGE SCREW

0012 420

BALANCE COCK

0171 353

BALANCE

COMPLETE WITH

STUD

0310 197

UPPER SHOCK

ABSORBING

SPRING

0014 577

UPPER HOLE JEWEL

FRAME FOR SHOCK-

ABSORBER 0014 295

UPPER SHOCK

ABSORBING CAP

JEWEL

0011 220

AUTOMATIC TRAIN BRIDGE

0191 183

SECOND REDUCTION WHEEL AND

PINION

0514 183

RATCHET WHEEL SCREW

0012 919

RATCHET WEEL

0285 051

PALLET BRIDGE SCREW

0012 354

PALLET BRIDGE

0161 300

PALLET FORK

0301 009

AUTOMATIC TRAIN BRIDGE SCREW

0012 354

󱢾

㉒

❶

㉖

㉕

󱣀

󱣂

㉗

24-2

24-3

24-4

24-1

⑳

⓲

⑲

󱣁

Cal. 4R37A

PARTS LIST

6/21

→Please refer to the following pages.



Lubricating: Types of oil

AO-3 (Moebius A)

SEIKO Watch Oil S-6

SEIKO Watch Oil S-4

[WINDING MECHANISM]

󱣅BARREL AND TRAIN WHEEL

BRIDGE SCREW

0012 420

CAP JEWELLED SPRING

0015 703

CAP JEWEL

0011 221

SLIDING CROWN

WHEEL SPRING

0363 184

BARREL AND TRAIN WHEEL

BRIDGE WITH HOLE JEWEL

FRAME

0114 183

LOWER PLATE FOR BARREL

AND TRAIN WHEEL BRIGDE

0436 164

THIRD WHEEL AND PINION

0231 070

LOWER PLATE FOR BARREL AND

TRAIN WHEEL BRIGDE SCREW

0012 354

CLICK

0381 004

BARREL COMPLETE WITH

MAINSPRING

0201 083

FIRST REDUCTION WHEEL

0511 010

PAWL LEVER

0831 183

REDUCTION WHEEL HOLDER

0836 002

FOURTH WHEEL AND PINION

0144 185

29-1

29-2

󱣆

󱣇

󱣋

󱣌

㊲

㊳

㊴

󱣊

󱣉

󱣈

㊱

Cal. 4R37A

PARTS LIST

7/21

→Please refer to the following pages.



Lubricating: Types of oil

AO-3 (Moebius A)

SEIKO Watch Oil S-6

SEIKO Watch Oil S-4

[SETTING MECHANISM]

CENTER WHEEL BRIDGE SCREW

0012 354

CENTER WHEEL BRIDGE

0122 302

ESCAPE WHEEL AND PINION

0251 300

CENTER WHEEL AND PINION

0224 185

YOKE SPRING SCREW

0012 168

SETTING LEVER JUMPER

0388 177

YOKE

0384 183

SETTING LEVER

0383 183

CLUTCH WHEEL

0282 183

WINDING PINION

0283 020

DATE CORRECTOR

SETTING TRANSMISSION

WHEEL A

0962 183

WINDING STEM

0351 200

BALANCE STEP LEVER

0601 183

Refer to page 11 for oiling spot

MAIN PLATE

0104 182

㊸

󱣕

㊺

㊻

㊼

㊵

㊶

㊷

󱣙

Cal. 4R37A

PARTS LIST

8/21

REMARKS

●How to ﬁnd the correct parts, if not determined by 4 digit caliber number

Following parts are determined based on the design of watches, such as hands height, dial color, and

design of cases. Please refer to the SEIKO WATCH PARTS CATALOGUE in order to choose corresponding

parts.

OSCILLATING WEIGHT 0509 ***

The type of OSCILLATING WEIGHT is determined based on the design of cases. Check the case number

and refer to the "SEIKO WATCH PARTS CATALOGUE" to choose corresponding OSCILLATING WEIGHT.

The type of DATE DIAL is determined based on the design of cases. Check the case number and refer to

the "SEIKO WATCH PARTS CATALOGUE" to choose corresponding DATE DIAL.

The type of WINDING STEM is determined based on the design of cases. Check the case number and

refer to the "SEIKO WATCH PARTS CATALOGUE" to choose corresponding WINDING STEM.

DATE DIAL 0878 ***

WINDING STEM 0351 ***

④

①

DIAL HOLDING SPACER 4408 ***

The type of DIAL HOLDING SPACER is determined based on the design of cases. Check the case number

and refer to the "SEIKO WATCH PARTS CATALOGUE" to choose corresponding DIAL HOLDING SPACER.

⑰

㊾

Cal. 4R37A

PARTS LIST

9/21

● How to discriminate resembled parts

Screws

0012354

0012168

0012485

0012919

0012420

DATE DISK GUARD SCREW (4 pcs.)

AUTOMATIC TRAIN BRIDGE (2 pcs.)

PALLET BRIDGE SCREW (2 pcs.)

LOWER PLATE FOR BARREL AND TRAIN WHEEL BRIGDE SCREW (1 pce.)

CENTER WHEEL BRIDGE SCREW (1 pce.)

②

⑱

㉕

㉟

㊵

YOKE SPRING SCREW (2 pcs.)

㊹

GUARD FOR DATE CORRECTOR SETTING TRANSMISSION WHEEL SCREW

(2 pcs.)

⑦

RATCHET WHEEL SCREW (1 pce.)

㉑

BALANCE BRIDGE SCREW (1 pce.)

BARREL AND TRAIN WHEEL BRIDGE SCREW (3 pcs.)

㉓

㉘

Cal. 4R37A

PARTS LIST

10/21

●Tools and consumables required for disassembling/reassembling

• Movement holder

 UNIVERSALMOVEMENTHOLDER(S-682)

• Watch oils

 SEIKOwatchgreaseS-6andS-4.watchoilAO-3(orMoebiusA)

S-6 AO-3

S-4

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