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
1
[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
24-1
*1
*1
*2
*2
*3
*3
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
󱣁
*1
*1
*2
*2
*3
*3

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
*1
*1
󱣆
󱣇
󱣋
󱣌
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
49
50
51
52
53
*1
*1
*2
*2
*3
*3
*4
*4
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