Seiko 8R48A, 8R49A Technical Manual
Movement
[Bridge side] [Calendar side]
Cal. 8R48A Cal. 8R49A
PARTS LIST / TECHNICAL GUIDE
Automatic Chronograph Cal. 8
R48A/8R49A
[SPECIFICATIONS]
1/24
Item
Cal. No.
8R48A/8R49A
34 jewels
Automatic winding with manual winding mechanism
+ 25 / - 15 seconds at normal temperature range
(Between 5°C and 35°C )
• Stopwatch function
Measures up to 12 hours
• Semi-instantaneous date change mechanism
• Second hand stop function
Date setting (counterclockwise only)
Time setting (Hour and minute)
Manual winding (clockwise only)
• Diameter Outside : Ø 28.6 mm
Casing: Ø 28.0 mm
• Height:
7.6 2 mm
• 3 hands (hour and minute hands, and small sec ond hand at
3 o'clock position)
• C alendar (Date: Da te disk)
28,800 (8 beats per second)
Testing
positions
± 10 s/d
Measurement
(daily rate in
seconds:s/d)
Dial upward
+ 20 s/d
– 10 s/d
ETACHRON system
From fully wound to stoppage: Approximately 45 hours
Movement size
52 °
6 o’clock
at the top up
Dial upward
9 o’clock
at the top up
Isochronous fault
Instantaneous rate at T0
(Fully wound condition)
+ 15 s/d
– 5 s/d
+ 20 s/d
– 10 s/d
Driving system
Additional function
Crown operation
Daily Date
Regulation system
Number of jewels
Normal position
1st click position
2nd click position
Lift angle of the escapment
Vibration per hour
Coutinuous operating time
Standard rate
for movement
Loss/Gain
SPECIFICATIONS
2/24
Cal. 8R48A/8R49A
Disassembling procedures figs. 1
93
Reassembling procedures Figs. 93 1
Types of oil Oil quantity mark
AO-3 (Moebius A) NORMAL QUANTITY
S-6
S-4 SUFFICIENT QUANTITY
[ NOTE ]
Please press button A to START the chronograph function before disassembly.
If it is at RESET position 41 Chronograph coupling lever A and 42 Chronograph coupling lever B are
under 47 Second counting intermediate wheel; it makes disassembly difficult.
Button B
Chronograph RESET
Button A
Chronograph START / STOP
1 0509 ***
Oscillating weight with ball bearing
*Refer to page 10 for the parts code
*1
*1
PARTS CATALOGUE
Cal. 8R48A/8R49A
3/24
*1
2 0016 709
Hour wheel guard screw
*3
3 0376 178
Hour wheel guard
4 0491 184
Dial washer A
5 0273 277
Hour wheel
7 0016 709
Date indicator maintaining plate screw
8 0808 178
Date indicator maintaining plate
10 0810 177
Date jumper
13 0595 177
Date corrector lever
14 0732 177
Date corrector cam
17 0012 092
Chronograph bridge screw
18 0190 ***
Chronograph bridge
* Refer to page 15 for the oiling
position.
* Refer to page 10 for the parts
code
17 0012 092
Chronograph bridge screw
16 0353 177
Second counting sheel spring
15 0012 092
Second counting wheel spring screw
12 0817 179
Intermediate date wheel and pinion
11 0802 178
Date indicator driving wheel
9 Date dial
6 0270 443
Center wheel
Intermediate date wheel
and pinion setting position
*5
*2
*4
*5
*2
*3
*1
Types of oil
AO-3 (Moebius A)
Oil quantity mark
NORMAL QUANTITY
SUFFICIENT QUANTITY
S-6
S-4
Oiling position
Second counting wheel spring
Second counting wheel
*4
Cal. 8R48A/8R49A
PARTS CATALOGUE
4/24
19 0491 182
Dial washer C
22 0886 183
Minute counter intermediate
wheel and pinion B
24 0902 ***
Minute counting wheel
* Refer to page 11 for
location of jewels.
20 0491 181
Dial washer B
Note:
Refer to the page 19 for distinguishing
the dial washers B, C and D.
21 0491 183
Dial washer D
23 0886 182
Minute counter intermediate
wheel and pinion A
25 0902 ***
Hour counting wheel
* Refer to page 11 for location of
jewels.
27 0894 177
Wheel stop lever
28 0587 179
Hammer operating lever B
26 0743 179
Hour chronograph coupling lever
* Refer to page 12 for the oiling
position.
30 0587 181
Hammer operating lever A
29 0782 177
Click spring
* Refer to page 12 for the oiling
position.
31 0585 177
Hammer
* Refer to page 14 for
the oiling position.
Note:
For the setting position of the spring
and lever etc., refer to page 16.
*2
*1*1
*2
*1
Types of oil
AO-3 (Moebius A)
Oil quantity mark
NORMAL QUANTITY
SUFFICIENT QUANTITY
S-6
S-4
34 0575 177
Operating lever spring
35 0571 179
Operating lever B
40 0837 178
Chronograph coupling lever holder
41 0581 179
Chronograph coupling lever A
PARTS CATALOGUE
Cal. 8R48A/8R49A
5/24
*1
*2
*1
*2
Note:
For the setting position of the spring
and lever etc., refer to page 16.
44 0240 ***
Second wheel
* Refer to page 10 for the parts
code.
42 0581 180
Chronograph coupling lever B
32 0571 177
Operating lever A
33 0012 092
Operating lever spring screw
45 0012 201
Operating cam screw
46 0576 180
Operating cam
* Refer to page 14 for the oiling
position.
47 0885 192
Second counter intermediate
wheel
36 0012 092
Operating cam jumper screw
37 1024 177
Operating cam jumper
38 0012 092
Chronograph coupling lever
spring screw
39 0584 178
Chronograph coupling
lever spring
43 0888 181
Second counting wheel
Types of oil
AO-3 (Moebius A)
Oil quantity mark
NORMAL QUANTITY
SUFFICIENT QUANTITY
S-6
S-4
Cal. 8R48A/8R49A
PARTS CATALOGUE
6/24
*1
48 0186 192
Chronograph main plate
* Refer to page 15 for the
oiling position.
49 0012 354
Unit intermeidate spacer
screw
50 4408 181
Unit intermediate spacer
51 0962 023
Date corrector setting
transmission wheel D
52 0962 023
Date corrector setting
transmission wheel C
53 0962 190
Date corrector setting
transmission wheel B
54 0817 180
Time setting transmission
wheel and pinion
55 0505 181
Second transmission wheel
* Refer to page 17 for the
setting position.
56 0505 182
Minutes transmission wheel
* Refer to page 14 for the
oiling position.
* Refer to page 17 for the
setting position.
57 Main plate
58 0012 092
Main plate screw
58 0012 092
Main plate screw
Types of oil
AO-3 (Moebius A)
Oil quantity mark
NORMAL QUANTITY
SUFFICIENT QUANTITY
S-6
S-4
*1
59 0012 420
Balance bridge screw
60 0171 349
Balance cock
60-1
0310 ***
Balance complete with stud
* Refer to page 10 for the parts code.
61 0012 354
Pallet bridge screw
62 0161 310
Pallet bridge
63 0301 315
Pallet fork
PARTS CATALOGUE
Cal. 8R48A/8R49A
7/24
*1
*1
Types of oil
AO-3 (Moebius A)
Oil quantity mark
NORMAL QUANTITY
SUFFICIENT QUANTITY
S-6
S-4
Cal. 8R48A/8R49A
PARTS CATALOGUE
8/24
64 0012 354
Automatic train bridge screw
65 0191 064
Automatic train bridge
66 0514 183
Second reduction whell and pinion
67 0012 919
Ratchet wheel screw
68 0285 051
Ratchet wheel
74 0511 010
First reduction whell and arbor
73 0831 183
Pawl lever
72 0836 002
Reduction wheel holder
69 0012 420
Barrel and train wheel
bridge screw
71 0363 184
Ratchet sliding wheel
spring
76 0436 166
Lower plate for barrel
and train wheel bridge
75 0012 354
Lower plate for barrel
and train wheel bridge
screw
70 0114 177
Barrel and train wheel bridge
* Refer to page 13 for the
oiling position.
Types of oil
AO-3 (Moebius A)
Oil quantity mark
NORMAL QUANTITY
SUFFICIENT QUANTITY
S-6
S-4
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