Hitachi G 10SG User manual

MODELS G 10SG/G 12SG
1. PRECAUTIONS IN DISASSEMBLY AND REASSEMBLY
The [Bold] numbers in the descriptions below correspond to the numbers in the Parts List and exploded
assembly diagram for G 10SG and the numbers <Bold> to those in the Parts List and exploded assembly
diagram for G 12SG.
1-1. Disassembly
1-1-1. Replacement of theArmature and Stator
(1) Remove the Brush Caps [47] <46> and take off theCarbon Brushes [48] <47>.
(2) Loosenthefour D5 x25Tapping Screws [1] <1> which fix the Gear Cover Ass'y [4] <4>, andtakeoff
Inner Cover [9] <9>together with the Armature [10] <10> from theHousing Ass'y [38] <38>.
At this time, make sure that the Rubber Bushing [16] <16> is fitted in the housing ball bearing chamber.
If the Rubber Bushing comes off the housing ball bearingchamber or adheres tothe Ball Bearing [15]
<15> reassemble the disc grinder according to 8 - 2. Reassembly.
(3) Loosen the two Tapping Screws (W/Flange) D4 x45 [58] <57> securing the Tail Cover [55] <54> and
remove the Tail Cover [55]<54>.
(4) Remove thefour internalwires from the Stator [13] connected with the Brush Holder [49] <48>, the Pillar
Terminal [44]<44>(or Connector [45]) and the Switch [50] <49>.
(5) Loosen the two Hex. Hd. Tapping Screws D4 x 70 [12] <12> securing the Stator [13] <13> and remove
the Stator [13] <13> from the Housing Ass'y [38] <38>. Ifyou have any trouble with removing the Stator
[13] <13>, heat the Housing Ass'y [38] <38> to about 60 C for easier dismantling.
1-1-2. Replacement of theRubber Busing
Insert the J-201 Spring HookH - 75 (Special Repair Tool) betweenthe RubberBushing [16] <16>
assembled in the Housing Ass'y [38] <38>and the housing ball bearing chamber and pull outthe
Rubber Bushing [16] <16>.
1-1-3. Replacement of theDust Seal
(1) Insert the hooks of the J-204 Bearing Puller (Special Repair Tool, Code No. 970982) between the Ball
Bearing [15] <15> and the Dust Seal [14] <14> and fix the hooks with the wing bolts.Be careful not to
insert thehook too much.
(2) Put the Bearing Puller on an appropriate stand. Push down the armature shaft with a hand press and
pull out the Ball Bearing [15] <15>.
(3) Pull out the Dust Seal[14] <14> from the armatureshaft.
−1−

1-1-4. Disassembly of the Pinion and Gear
(1) Loosen the M7 Special Nut[5] for G 10SG (M6
Special Nut <5> forG12SG)on theArmature [10]
<10>, and removethePinion[6] <6>.
(2) Loosen the four M4 x 12 Seal Lock Screws[24]
<24>which fix the Packing Gland [23]<23>, and
remove the Gear Cover Ass'y [4] <4>.
(3) As illustrated in Fig. 5, support the outer
circumferenceof the Gear[18] <18> with a J-129
Gear Puller
(Special Repair Tool, Code No. 970905), and push
down on the upper portion of the Spindle[26] <27>
with a hand press to separate the Gear [18] <18>
from theSpindle[26] <27>.
1-2. Reassembly
Put the parts together in the reverse order of disassembly, with the precautions given below.
(1) Generously lubricatetheteethofGear [18] <18> and Pinion [6] <6> with grease.Rubgrease onto the
teeth with yourfingers so that the grease reaches each tooth bottom. Note that the Gear[18] <18>and
Pinion [6] <6>if under-lubricated may wear at an faster rate.
(2) Be sure to soak the inner diameter of the Felt Packing [22] <22> with machineoil. Otherwise, its
dust-sealing function will fail to work properly, resulting in anearlier damage of the Ball Bearing [21] <21>.
(3) When replacing the ArmatureAss'y [10] <10>and the Ball Bearing [15] <15> on the commutator side,
press inward on the Dust Seal[14] <14> while taking care of itsdirection until the end face of the Dust
Seal [14] <14>hits against the a butting surface of the Armature Ass'y [10] <10> and make sure that Dust
Seal [14] <14> cannotturn freely. Keep the end face of the armature shaft approximately 0.2mm
(reference) distance inward of the end face of the Ball Bearing [15]<15>. (SeeFig. 6)
The Dust Seal [14] <14> is an important element for improved dust protection of the Ball Bearing [15]
<15>. Be sure to use a new one upon replacement.
Fit the Rubber Bushing [16] <16> into the housing ball bearing chamber before installing the Armature
Ass'y [10] <10>. (SeeFig. 7)
−2−
[18] J-129 Gear Puller
Fig. 5
[26]
<18> <27>
About 0.2mm (reference)
Armature shaft
Ball Bearing[15] <15>
Dust Seal [14] <14>
Fig. 6
Housing ball bearing chamber
Rubber Bushing [16] <16>
About 4.5mm
Fig. 7

(4)When installing the Stator[13] <13> into the Housing Ass'y[38] <38>, insert it while takingcare of the
placement of the internal wires of the Stator [13] <13> as indicated in Fig. 8.
Connect the four internal wires of Stator [13] <13> with the parts indicatd in Fig. 8
(5) When connecting the Earth Terminal [40] <40> to the internal wire (the middle wire among three) of the
Noise Suppressor[42] <42>, strip theinsulation sheath on the internal wire by about 6 mm andpress
connect it together with the Earth Terminal [40]<40>with a clamping tool on the market.
(6) When replacing the Gear Cover Ass'y [4] <4>, lubricate the metal part with mixed oil.
Mixed oil: Mixture of Hitachi power tool grease No. 2 (Unilube No.00) and tubine oil
* Mixure ratio....1:1(weight ratio) * Volume....0.5cc
−3−
Connect to the Brush Holder
[49] <48> (onthesamesideas the
Name Plate[39] <39>.)
Connect to the Brush Holder
[49] <48> (on the samesideas the
Hitachi Label [46] <45>.)
Connect to the Cord [59] <58> with a Pillar
Terminal [44] <44> or clamp totheCord [59]
<58>with a Connector [45].
Fig. 8
Both the internal wire of the Noise
Suppressor [42] <42> and this wire
are connected to the Terminal [41]
with solderless connection and
connect it totheSwitch[50] <49>
(if the Noise Suppressor [42]is not
used, connect this internal wire to
the Switch [50] <49> After
clamping the Terminal [41] <41>
with solderless connection.
Fig. 9
Solderless connection

1-3. Lubrication Points andTypes ofLubricant
* Pinion chamber of Gear Cover Ass'y [4] <4>...........Nippekogrease (SEP-3A) 10 g
* Metal...................................................................Mixedoil 0.5cc
Mixed oil: Mixture of Hitachi power tool grease
No.2
(Unilube No. 00) and turbine oil
Mixture ratio.....1:1(weight ratio)
1-4. Tightening Torque
D4 Tapping Screw [12] <12> [53] <52> [58] <57>........2.00.5 Nm (20 5kgfcm, 1.50.4ft-lbs)
M4 Slotted Hd. Screw (Seal Lock) [7] <7>.....................1.80.4 Nm (18 4kgfcm, 1.30.3 ft-lbs)
M4 Seal Lock Screw (W/SP. Washer)[19] <19> [24] <24>
........................1.80.5 Nm (18 4kgfcm, 1.30.3 ft-lbs)
D5 Tapping Screw [1] <1>.............................................2.90.5 Nm (30 5kgfcm, 2.20.4 ft-lbs)
M5 Machine Screw (W/SP. Washer)[28] <28>..............1.6 0.4Nm (164 kgfcm, 1.2 0.3 ft-lbs)
Special Nut M7 [5].........................................................6.4 1.0Nm (6510 kgfcm, 4.7 0.7 ft-lbs)
Special Nut M6 <5>.......................................................6.4 1.0Nm (6510 kgfcm, 4.7 0.7 ft-lbs)
Brush Cap [47] <46>.....................................................0.6 0.2Nm (62 kgfcm, 0.4 0.1ft-lbs)
−4−
Generously rub grease onto the Gear and Pinion.

1-5. WiringDiagrams
−5−
For China
Stator [13]<13>
Black
Switch [50] <49>
Brown
Blue Cord [59] <58>
Pillar Terminal [44] <44>
For Hong Kong and Indonesia
Stator [13] <13> Switch [50] <49>
Cord [59] <58>
Connector [45]
For Other Countries
Stator [13] <13> Switch [50] <49>
Pillar Terminal [44] <44>
Black
or
Brown
Black Black
Black
White
or
Blue
Black
Black
Black
Black
Black
Black Black
Black
Cord [59] <58>

1-6. Insulation Tests
On completion of disassembly and repair, measure the insulation resistance, and conduct the dielectric
strength test.
Insulation resistance : 7 MΩor more with 500 V DC Megohm Tester
Dielectric strength test : AC 4,000 V/1 minute, with no abnormalities............220V - 240 V
(and110 Vfor U.K. products)
AC 2,500 V/1 minute, with no abnormalities............110V - 127 V
(expect U.K. products)
1-7. No-Load CurrentValue
After no-load operation for 30 minutes, the no-load current value should be as follows.
−6−
Voltage
Current (A) max.
110 V 115 V 220 V 230 V 240 V
2.72.7 1.35 1.351.38

2. STANDARD REPAIR TIME (UNIT) SCHEDULES
−7−
Switch
SwitchHolder
Tail Cover
CordArmor
Brush Holder
Work Flow
G 10SG
General Assembly
Wheel Guard
Ass'y
PushingButton
Gear Cover
Ass'y
Lock Pin
Gear
Bearing
Cover (B)
Ball Bearing
(6001VV)
Felt Packing
Packing Gland
Spindle
Fringer
Pinion
Ball Bearing
(608VV)
Ball Bearing
(626VV)
Inner Cover
Armature
Dust Seal
Rubber
Bushing
Housing Ass'y
Stator
Slide Bar
Spring
Slide knob
G 12SG
MODELVariable
Fixed 10 20 304050 60 min.