Hitachi G 12SA2 Manual

POWER TOOLS
TECHNICAL DATA
AND
SERVICE MANUAL
DISC GRINDER
G 12SA2
G 13SB2
SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT
LIST Nos. E239, E240 Feb. 2001
G
MODEL G 12SA2
G 13SB2

Page
CONTENTS
1. PRODUCT NAME.........................................................................................................................1
2. MARKETING OBJECTIVE ...........................................................................................................1
3. APPLICATIONS............................................................................................................................1
4. SELLING POINTS ........................................................................................................................1
5. SPECIFICATIONS ........................................................................................................................3
6. COMPARISONS WITH SIMILAR PRODUCTS ............................................................................4
6-1. Specification Comparisons ........................................................................................................... 4
6-2. Practical Test Data ........................................................................................................................ 4
7. PRECAUTIONS IN SALES PROMOTION ...................................................................................5
7-1. Handling Instructions .................................................................................................................... 5
7-2. Caution on Name Plate................................................................................................................. 5
7-3. Precautions on Usage................................................................................................................... 5
8. PRECAUTIONS IN DISASSEMBLY AND REASSEMBLY ..........................................................6
8-1. Disassembly.................................................................................................................................. 6
8-2.Reassembly ................................................................................................................................... 8
8-3. Lubrication Points and Types of Lubricant .................................................................................. 10
8-4. Tightening Torque ....................................................................................................................... 10
8-5. Wiring Diagrams ..........................................................................................................................11
8-6. Insulation Tests ........................................................................................................................... 12
8-7. No-load Current Value ................................................................................................................ 12
9. STANDARD REPAIR TIME (UNIT) SCHEDULES .....................................................................13
[Appendix]
Assembly Diagrams for G 12SA2 / G 13SB2

--- 1 ---
1. PRODUCT NAME
Hitachi Electronic Disc Grinder, Model G 12SA2 115 mm (4-1/2")
Model G 13SB2 125 mm (5")
2. MARKETING OBJECTIVE
The Models G 12SA and G 13SB Disc Grinders have been on the market for 15 years. To meet a strong demand
for a remodeled, we now offer totally renewed design with increased power input, for increased competitiveness
and expanded sale.
The Models G 12SA2 and G13SB2 have been developed to upgrade and replace the current Models G 12SA and
G 13SB.
The key features for the Models G 12SA2 and G 13SB2 are as follows:
(1) Powerful motor with input of 950 W (Depends on market)
(2) Excellent overload durability
(3) Prolonged service life of the carbon brushes
(4) Compact, lightweight and easy to operate
(5) Renewed design
3. APPLICATIONS
Deburring diecast products and finishing iron, bronze, aluminum and diecast products
Finishing welds and torch-cut surfaces
Cutting soft steel materials
Grooving and cutting concrete and other stone materials
4. SELLING POINTS Prolonged service life of the carbon brushes:
1.4 times higher compared to maker B's model
2.2 times higher compared to maker C's model
Low noise, cooling-air-flow design: 84 dB
Maker B's model: 88 dB
Maker C's model: 86 dB
Excellent overload durability:
1.3 times higher compared to maker B's model
1.3 times higher compared to maker C's model
Compact body: 285 mm (11-1/4")
Maker B's model: 298 (11-3/4")
Maker C's model: 305 (12")
High power
(with maximum output of 1,430 W)
Maker B's model: 1,190 W
Maker C's model: 1,430 W
Wear resistance of armature coil
285 mm (11-1/4")

--- 2 ---
Excellent overload durability
The Models G 12SA2 and G 13SB2 provide excellent overload durability thanks to an improved cooling
mechanism and a high-power motor.
Practical test data: Comparison of torque when the stator coil temperature rise is 200˚ K
Fig. 2
Coating of heat-resistant adhesive
Fig. 1
Prolonged service life of the carbon brushes
The service life of the carbon brushes is prolonged thanks to the adoption of the internally placed carbon
brushes and the improved winding specifications.
Practical test data: Comparison of service life of carbon brushes in the continuous rated load test
Wear resistance of armature coil
Both ends of the armature coil are sealed with heat-resistant adhesive in addition to varnish treatment to
minimize wear of the armature coil caused by dust.
100 50 0
B
C
G 12SA2
G 13SB2
G 12SA
G 13SB
100
85
76
79
100 50 0
B
C
G 12SA2
G 13SB2
G 12SA
G 13SB
100
52
45
71
Fig. 3

--- 3 ---
Depressed-
center
wheels
5. SPECIFICATIONS
4,800 m/min (15,756 ft/min)
A, 36, Q, B
M14 x 1.2 M14 x 1.2
Dimensions
Model
Item
O.D. 115 mm (4-1/2")
x Thickness 6 mm (1/4")
x I.D. 22.2 mm (7/8")
O.D. 125 mm (5")
x Thickness 6 mm (1/4")
x I.D. 22.2 mm (7/8")
Max. practical
peripheral speed
Type
G 12SA2 G 13SB2
AC single phase 50 or 60 Hz
Power source
Slide switch
1.9 kg (4.2 lbs.)
3.2 kg (7.1 lbs.) 3.3 kg (7.2 lbs.)
Corrugated cardboard box
No-load speed
Type of motor
Enclosure
Type of switch
Weight Net: *(main body)
Gross:
Type of packing
Standard accessories Depressed-center wheel
115 mm (4-1/2") ......................1
Side handle .............................1
Wrench....................................1
Voltage and power input
10,000/min
AC single phase commutator motor
Housing (Green)
Tail cover (Black)
Gear cover, packing gland ................ Aluminum alloy diecasting
........................Polyamide resin with glassfiber
Depressed-center wheel
125 mm (5") ............................1
Side handle .............................1
Wrench....................................1
○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○
Voltage (V) Current (A) Power input (W)
110
230
120
850
950
880
8.1
4.4
7.7
* Net weight excludes cord, side handle, depressed-center wheel, wheel nut, wheel washer and wheel guard.
Spindle thread
Optional accessories Super washer (Code No. 310338)

--- 4 ---
115/125
(4-1/2"/5")
900
430
1,430
10,000
86
95
1.75 (3.9 lbs.)
1.8 (4.0 lbs.)
305 (12")
90 (3-35/64")
HITACHI
G 12 SA2
G 13SB2
115/125
(4-1/2"/5")
950
690
1,430
10,000
84
210
1.9 (4.2 lbs.)
2.0 (4.4 lbs.)
285 (11-1/4")
70 (2-3/4")
Maker
Model name
Capacity:
Depressed-center wheel dia. (mm)
Power input *1 (W)
Power output *1 (W)
Max. power output *1 (W)
No-load speed (/min)
No-load sound pressure level (dB/A)
Service life of carbon brushes *2 (hr)
Weight *3 (kg)
(Actual weight) (kg)
Dimensions L (mm)
H (mm)
6. COMPARISONS WITH SIMILAR PRODUCTS
6-1. Specification Comparisons
G 12SA
G 13SB
115/125
(4-1/2"/5")
750
520
1,150
10,000
80
110
2.1 (4.6 lbs.)
2.2 (4.9 lbs.)
288 (11-5/16")
70 (2-3/4")
125
(5")
900
540
1,190
11,000
88
150
1.75 (3.9 lbs.)
1.8 (4.0 lbs.)
298 (11-3/4")
70 (2-3/4")
*1 Depends on market
*2 Service life of carbon brushes in the
continuous rated load test
*3 Weight without cord, side handle, depressed-
center wheel, wheel nut, wheel washer and
wheel guard
6-2. Practical Test Data
Comparison of temperature rise of stator coil section:
The graph below shows the relationship between load and temperature rise of the stator coil. The temperature
rise of the Models G 12SA2 and G 13SB2 is the lowest among similar models. This means that the resistance to
overload usage of the Models G 12SA2 and G 13SB2 is superior to other models.
Fig. 4
Load
Stator coil temperature rise (K)
200
50
100
150
0
C
G 12SA2
G 13SB2
G 12SA
G 13SB
B
BC
L
H

--- 5 ---
7. PRECAUTIONS IN SALES PROMOTION
In the interest of promoting the safest and most efficient use of the Models G 12SA2 and G 13SB2 Disc Grinders
by all of our customers, it is very important that at the time of sale, the salesperson carefully ensures that the
buyer seriously recognizes the importance of the contents of the Handling Instructions, and fully understands the
meaning of the precautions listed on the Name Plate or Caution Plate attached to each tool.
7-1. Handling Instructions
Although every effort is made in each step of design, manufacture and inspection to provide protection against
safety hazards, the dangers inherent in the use of any electric power tool cannot be completely eliminated.
Accordingly, general precautions and suggestions for the use of electric power tools, and specific precautions and
suggestions for the use of the disc grinders are listed in the Handling Instructions to enhance the safe and efficient
use of the tool by the customer. Salespersons must be thoroughly familiar with the contents of the Handling
Instructions to be able to offer appropriate guidance to the customer during sales promotion.
7-2. Caution on Name Plate
Each tool is provided with a Name Plate which contains the following basic safety precautions in the use of the
tool.
7-3. Precautions on Usage
Never press the pushing button while the depressed-center wheel is rotating.
If the pushing button is pressed while the depressed-center wheel is rotating, the spindle will stop immediately.
In such a case, there is a danger that the wheel nut may be loosened so that the depressed-center wheel flies off
unexpectedly to cause possible serious injury.
(1) For New Zealnad
(2) For U.S.A. and Canada

--- 6 ---
Fig. 5
8. PRECAUTIONS IN DISASSEMBLY AND REASSEMBLY
The [Bold] numbers in the descriptions below correspond to the numbers in the Parts List and the exploded
assembly diagram for G 12SA2, and the <Bold> numbers to those in the Parts List and the exploded assembly
diagram for G 13SB2.
8-1. Disassembly
(1) Removal of the Armature [14] <14>
1. Loosen the Machine Screw M5 x 20 [32] <32>, and remove the Wheel GuardAss'y [34] <34>.
2. Loosen the Tapping Screw (W/Flange) D4 x 16 (Black) [56] <55>, and remove the Tail Cover [55] <54>.
3. Remove the two Carbon Brushes [46] <45> from the Brush Holders [47] <46>.
4. Remove the four Tapping Screws D5 x 25 [1] <1>. The Armature [14] <14> can then be taken out
simultaneously with the Gear Cover Ass'y [4] <4>, Packing Gland [28] <28>, and related parts.
5. Remove the four Seal Lock Screws (W/SP. Washer) M5 x 16 [29] <29>.
6. After removing the three Seal Lock Screws (W/SP. Washer) M4 x 10 [20] <20>, the Armature [14] <14> can be
extracted together with the Bearing Cover [13] <13>, and related parts.
7. Carefully wrap theArmature [14] <14> with a soft, clean rag to protect it from being damaged, and clamp it
securely in a vise. Then, remove the Special Nut M7 [6] <6>, and extract the Pinion [7] <7>.
8. For the models indicated under Fig. 5, the Ball Bearing [10] <10> can be removed from theArmature [14]
<14> by utilizing a J-204 Bearing Puller (special repair tool, Code No. 970982) as illustrated. After the Ball
Bearing has been removed, the Bearing Cover [13] <13> can be easily taken off.
Bearing Puller (Code No. 970982)

--- 7 ---
(2) Removal of the Dust Seal [18] <18>
1. Insert the hooks of the J-204 bearing puller between the commutator and the Dust Seal [18] <18> from both
sides, and fix the hooks with the wing bolts.
2. Place the J-204 bearing puller on a supporting jig and push down on the armature shaft with a hand press to
remove the Dust Seal [18] <18> together with the Ball Bearing [19] <19>. Replace the Dust Seal [18] <18>
with new one because it is damaged by the removal of the Ball Bearing [19] <19>.
(3) Removal of the Stator [17] <17>
1. After removing the Armature [14] <14> and Pushing Button Switch [49] <48>, disconnect the lead wires
connected to the Brush Holders [47] <46>.
2. Loosen the two Hex. Hd. Tapping Screws D4 x 70 [16] <16> and remove the Stator [17] <17> from the
Housing [40] <40>. If the Stator [17] <17> cannot be easily removed from the Housing [40] <40>,
disassembly can be facilitated by heating the Housing [40] <40> to a temperature of approximately 60˚C
(140˚F) with an appropriate heating device.
(4) Removal of the Gear [22] <22>
1. Loosen the four Seal Lock Screws (W/SP. Washer) M5 x 16 [29] <29>, and remove the Packing Gland [28]
<28> together with the Spindle [31] <31> and Gear [22] <22> from the Gear Cover Ass'y [4] <4> in a single
body.
2. When it is necessary to remove the Gear [22] <22> from the Spindle [31] <31>, it is highly recommended that
the special repair tools described below are utilized.
As illustrated in Fig. 6, support the angled
surface of the Gear [22] <22> with a J-129-2
Gear Puller (special repair tool, Code No.
970906), rest the J-129-2 Gear Puller on a
J-130 Sleeve (special repair tool, Code No.
970907), and push down on the tip of the
Spindle [31] <31> with a hand press to remove
the Gear [22] <22>.
(5) Removal of the Slide Knob [39] <39>
1. Loosen the Tapping Screw (W/Flange) D4 x 16 (Black) [56] <55> and remove the Tail Cover [55] <54>.
2. Hold the Housing [40] <40> and raise the Slide Bar [44] <43> until the Slide Knob [39] <39> moves to the
"ON" position.
3. Check that the Slide Knob [39] <39> has not moved to the "ON-LOCK" position, and push down the Slide
Knob [39] <39> until it clicks while keeping the Slide Bar [44] <43> raised.
4. Raise the Slide Knob [39] <39> straight up and remove it keeping the Slide Bar [44] <43> raised.
J-129-2
Gear Puller
Push
J-130
Sleeve
Fig. 6

--- 8 ---
(6) Removal of the Pushing Button Switch [49] <48>
1. Loosen the Tapping Screw (W/Flange) D4 x 16 (Black) [56] <55> and remove the Tail cover [55] <54>.
2. Loosen the two Tapping Screws (W/Flange) D4 x 20 (Black) [58] <57> and remove the Switch Holder [50]
<49> from the Housing [40] <40>.
3. Pressing the Pushing Button Switch [49] <48> in the arrow "A" direction, press the latches of the Switch
Holder [50] <49> in the arrow "B" direction with a small flat-blade screwdriver to remove the Pushing Button
Switch [49] <48> from the Switch Holder [50] <49> (See Fig. 7).
4. Pressing the button of the Pushing Button Switch [49] <48> in the arrow "C" direction, press the Pushing
Button Switch [49] <48> in the arrow "A" direction to remove the Pushing Button Switch [49] <48>
(See Fig. 8).
8-2.Reassembly
Put the parts together in the reverse order of disassembly, with the precautions given below.
(1) Generously lubricate the teeth of Gear [22] <22> and Pinion [7] <7> with grease. Rub grease onto the teeth
with your fingers so that the grease reaches each tooth bottom. Note that under-lubricated Gear [22] <22>
and Pinion [7] <7> may wear at a faster rate.
Fig. 8
B
Fig. 7
Switch
Switch holder
A
B
A
A
C
Switch Switch holder
Button
Latches