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PRODUCT NAME
Hitachi Disc Grinder
Models 100 mm (4”) G 10SS2(S)
115 mm (4-1/2”) G 12STA(S), G 12STX
125 mm (5”) G 13STA(S)
LIST Nos.
G 10SS2(S): F233
G 12STA(S): F235
G 12STX: F242
G 13STA(S): F237
Feb. 2016
CONTENTS
REPAIR GUIDE ---------------------------------------------------------------------------------------------------------------- 1
1. Precautions on disassembly and reassembly ----------------------------------------------------------- 1
STANDARD REPAIR TIME (UNIT) SCHEDULES -------------------------------------------------------------------- 6
Page
G
G
Overseas Sales Division
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WARNING: Before attempting disassembly, be sure to turn off the power switch and disconnect
the plug from the power source outlet.
REPAIR GUIDE
1. Precautions on disassembly and reassembly
[Bold] numbers in the description below correspond to the item numbers in the parts lists and exploded
assembly diagrams of the Models G 10SS2(S), and <Bold> numbers to those of the Models G 12STA(S),
G 12STX and G 13STA(S).
1. Removal of the armature and stator
(1) Loosen the Screw D4 x 16 [41]<40> and pull out the Tail Cover [40]<39>. Remove the two Carbon
Brushes (1 Pair) [27]<26> from the Brush Holders [31]<30>.
(2) Loosen the four Screws D4 x 23 [1]<1> that fix the Gear Cover Ass’y [3]<3> to remove the Armature
[7]<7> from the Housing [26]<25> together with the Bearing Holder [6]<6>. At this time, check that the
Rubber Bushing [25]<24> is fitted in the housing ball bearing chamber.
(3) Loosen the Special Nut M6 [4]<4> that fixes the Gear and Pinion Set [21]<20> and remove the Gear
and Pinion Set [21]<20>.
(4) Insert the hooks of the J-204 bearing puller (special repair tool, Code No. 970982) between the Ball
Bearing 608S [5]<5> and Bearing Holder [6]<6> from both sides and secure the hooks in place with
the wing bolts.
(5) Put the J-204 bearing puller on an appropriate stand. Push down the armature shaft with a hand press
to remove the Ball Bearing 608S [5]<5>. Then remove the Bearing Holder [6]<6>.
(6) Remove the four internal wires connected to the Tab Terminal [28]<27> and Pushing Button Switch
[32]<31> from the Stator [9]<9>.
(7) Remove the Fan Guide [8]<8> and Stator [9]<9> from the Housing [26]<25>.
NOTE: • If you have any trouble in removing the Stator [9]<9>, heat the Housing [26]<25> to
about 60°C for easier removal.
• The internal wire (single wire) of the Stator [9]<9> is covered with a heat-shrinkable
tube. Do not forcefully bend the internal wire of the Stator [9]<9> repeatedly and do not
peel off the heat-shrinkable tube when removing the Stator [9]<9> from the Housing
[26]<25>. Otherwise, the internal wire may be disconnected.
• Do not forcefully bend the stator terminal when removing the stator terminal from the
Pushing Button Switch [32]<31> and the tab terminal. Otherwise, the stator terminal
may be broken.
2. Removal of the rubber bushing
Insert the J-201 spring hook H-75 (special repair tool) between the Rubber Bushing [25]<24> assembled
in the Housing [26]<25> and the housing ball bearing chamber, and then pull out the Rubber Bushing
[25]<24>.
3. Removal of the dust seal
(1) Insert the hooks of the J-204 bearing puller between the Ball Bearing 626ZZ [24]<23> and the Dust
Seal [23]<22> and fix the hooks with the wing bolts. Be careful not to insert the hooks excessively.
(2) Put the bearing puller on an appropriate stand. Push down the armature shaft with a hand press and
pull out the Ball Bearing 626ZZ [24]<23>.
(3) Pull out the Dust Seal [23]<22> from the armature shaft.
Disassembly
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4. Removal of the gear and pinion set
(1) Loosen the four Screws M4 x 12 [13]<13> and remove the
Packing Gland [12]<12> from the Gear Cover Ass'y [3]<3>.
(2) Remove the Retaining Ring for D11 Shaft [11]<11> that
secures the Gear and Pinion Set [21]<20> to the Spindle
[15]<15>.
(3) When it is necessary to remove the Gear and Pinion Set
[21]<20> from the Spindle [15]<15>, it is highly
recommended that the special repair tools described below
are utilized.
Place the assembly on a sleeve that matches the
dimension of the Packing Gland [12]<12> and push down
on the top of the Spindle [15]<15> with a hand press to
remove the Gear and Pinion Set [21]<20> as shown in Fig.
1.
Reassembly
Fig. 1
Push.
[15]<15>
[21]<20>
[12]<12>
Sleeve
Reassembly can generally be conducted by reversing the disassembly procedure. However, special
attention should be given to the following items.
(1) Generously lubricate the teeth of the Gear and Pinion Set [21]<20> with grease. Rub grease onto the
teeth with your fingers so that the grease reaches each tooth bottom. Note that under-lubricated Gear
and Pinion Set [21]<20> may wear at a faster rate.
(2) When replacing the Armature [7]<7> and the Ball Bearing 626ZZ [24]<23> on the commutator side,
press in on the Dust Seal [23]<22> while carefully noting its direction until the end face of the Dust
Seal [23]<22> contacts the butting surface of the Armature [7]<7>, and check that the Dust Seal
[23]<22> cannot turn freely. Keep the end face of the armature shaft at a distance of about 0.2 mm
(reference) from the end face of the Ball Bearing 626ZZ [24]<23>. (See Fig. 2.)
The Dust Seal [23]<22> is an important element for improved dust protection of the Ball Bearing
626ZZ [24]<23>. Be sure to replace it with a new one at every disassembly work. Fit the Rubber
Bushing [25]<24> into the housing ball bearing chamber before installing the Armature [7]<7>. (See
Fig. 3.)
Fig. 2
Fig. 3
Housing ball bearing chamber
[25]<24>
About 0.2 mm (reference)
Armature shaft
[23]<22>
[24]<23>
About 4.5 mm
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(3) Before inserting the Stator [9]<9> into the Housing [26]<25>, correctly connect the internal wires of the
Stator [9]<9> to each part without entangling as shown in Fig. 4.
NOTE: • Be careful not to put the internal wire of the Carbon Brush [27]<26> between the
Housing [26]<25> and the internal wires of the Stator [9]<9> when connecting the
internal wires of the Stator [9]<9> or when connecting the Carbon Brush [27]<26>.
• The internal wire (single wire) of the Stator [9]<9> is covered with a heat-shrinkable
tube. Do not forcefully bend the internal wire of the Stator [9]<9> repeatedly and do
not peel off the heat-shrinkable tube when mounting the Stator [9]<9> to the Housing
[26]<25>. Otherwise, the internal wire may be disconnected.
• Do not forcefully bend the stator terminal when inserting the stator terminal into the
Pushing Button Switch [32]<31> and the tab terminal. Otherwise, the stator terminal
may be broken.
Fig. 4
White
Connect the internal wire to the
Pushing Button Switch [32]<31>.
[9]<9>
Connect the internal wires to
the Tab Terminal [28]<27>.
[26]<25>
Connect the internal wire to the
Pushing Button Switch [32]<31>.
White
Lubrication point and type of lubricant
(1) When replacing the Gear Cover Ass’y [3]<3>, lubricate the metal with the following mixed oil.
Mixed oil: Mixture of Hitachi power tool grease No. 2 (Unilube No. 00) and turbine oil
• Mixture ratio: 1:1 (weight ratio)
• Volume: 0.5 cc
(2) Generously rub 10 g of Shell GADUSS2V1003 grease onto the gear and pinion of the Gear Cover
Ass'y [3]<3>.
Tightening torque
• Seal Lock Screw (W/Washer) M4 x 12 [13]<13> -------- 1.8 ± 0.5 N•m (18 ± 4 kgf•cm, 1.3 ± 0.3 ft-lbs.)
• Tapping Screw (W/Flange) D4 [41][36]<40><35> ------ 2.0 ± 0.5 N•m (20 ± 5 kgf•cm, 1.5 ± 0.4 ft-lbs.)
• Machine Screw (W/Sp. Washer) M5 x 16 [16]<16> ---- 3.4 ± 0.7 N•m (35 ± 7 kgf•cm, 2.5 ± 0.5 ft-lbs.)
• Special Nut M6 [4]<4> ----------------------------------------- 4.9 ± 1.0 N•m (50 ± 10 kgf•cm, 3.6 ± 0.7 ft-lbs.)
• Tapping Screw D3 x 8 [29]<28> ----------------------------- 0.6 ± 0.1 N•m (6.2 ± 1.2 kgf•cm, 0.4 ± 0.07 ft-lbs.)
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Insulation test
On completion of disassembly and repair, measure the insulation resistance and dielectric strength.
Insulation resistance: 7 MΩ or more with a 500 VDC megohm tester
Dielectric strength test: 4,000 VAC/minute, with no abnormalities ---------- 230 V
2,500 VAC/minute, with no abnormalities ---------- 110 V
No-load current value
After no-load operation for 30 minutes, the no-load current values should be as follows.
Voltage 110 V 230 V
Current max. 2.8 A 1.1 A
Wiring diagram
Fig. 5
Black
Black
Stator [9]<9>
Gray
Stator [9]<9>
Black
2
C2
C1
1
Black
Pushing Button Switch [32]<31>
Controller
Red
White
Varistor (A) Ass’y
[43]<42>
Brown
Blue
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STANDARD REPAIR TIME (UNIT) SCHEDULES
MODEL
G 10SS2(S)
G 12STX
G 12STA(S)
G 13STA(S)
Fixed
Variable
General Assembly
10 20 30 40 50 60 min.
Work Flow
Pushing
Button
Switch
Tail Cover
Cord
Cord Armor
Varistor (A)
Ass’y
Wheel Guard
Ass'y
Housing
Stator
Slide Bar
Slide Switch
Armature
Ball Bearing
(608SS)
Bearing
Dust Seal
Ball Bearing
(626ZZ)
Rubber
Bushing
Gear Cover
Pushing
Button
Lock Pin
Packing
Spindle
Knob
Cover
Ass’y
Gland
Gear and
Pinion Set
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