Hitachi WR 12DMR Instruction manual

TECHNICAL DATA
AND
SERVICE MANUAL
SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT
LIST Nos. WH 12DMR: G814
WR 12DMR: G821
Revised Jun. 2005
W
MODELS
WH 12DMR
WR 12DMR
Hitachi 
Power Tools
CORDLESS IMPACT DRIVER
WH 12DMR
CORDLESS IMPACT WRENCH
WR 12DMR
WH 12DMR WR 12DMR

REMARK:
Throughout this TECHNICAL DATA AND SERVICE MANUAL, a symbol(s)
is(are) used in the place of company name(s) and model name(s) of our
competitor(s). The symbol(s) utilized here is(are) as follows:
Symbol Utilized
Competitor
Company Name Model Name
WH 12DMR
Symbol Utilized
Competitor
Company Name Model Name
WR 12DMR
P1 DEWALT DW051
P2 DEWALT DW053
PDEWALT DW052

Page
CONTENTS
1. PRODUCT NAME ................................................................................................................................ 1
2. MARKETING OBJECTIVE .................................................................................................................. 1
3. APPLICATIONS ................................................................................................................................... 1
4. STANDARD EQUIPMENT ................................................................................................................... 1
5. SELLING POINTS ............................................................................................................................... 2
5-1. Selling Point Descriptions ..................................................................................................................... 4
6. SPECIFICATIONS ............................................................................................................................... 7
6-1. Specifications ........................................................................................................................................ 7
6-2. Optional Accessories ............................................................................................................................ 9
7. COMPARISONS WITH SIMILAR PRODUCTS ................................................................................. 12
7-1. Specification Comparisons (Cordless Impact Driver) .........................................................................12
7-2. Specification Comparisons (Cordless Impact Wrench) ...................................................................... 13
7-3. Tightening Torque ...............................................................................................................................14
7-4. Tightening Time .................................................................................................................................. 17
7-5. Number of Screws or Bolts Driven ...................................................................................................... 18
8. PRECAUTIONS IN SALES PROMOTION ........................................................................................ 19
8-1. Safety Instructions ..............................................................................................................................19
8-2. Tightening Torque Inspection Prior to Operation ................................................................................ 22
8-3. Tightening Torque Variation ................................................................................................................22
8-4. Suggestions and Precautions for the Efficient Use of the Charger ..................................................... 23
9. OTHER PRECAUTIONS ................................................................................................................... 24
10. REPAIR GUIDE ............................................................................................................................... 25
10-1. Precautions in Disassembly and Reassembly .................................................................................. 25
10-2. Precautions in Disassembly and Reassembly of Battery Charger ................................................... 33
11. STANDARD REPAIR TIME (UNIT) SCHEDULES........................................................................... 34
For Model WH 12DMR ...............................................................................................................................34
For Model WR 12DMR ...............................................................................................................................35
Assembly Diagram for WH 12DMR
Assembly Diagram for WR 12DMR

--- 1 ---
1. PRODUCT NAME
Hitachi Cordless Impact Driver, Model WH 12DMR
Hitachi Cordless Impact Wrench, Model WR 12DMR
2. MARKETING OBJECTIVE
The current Models WH 12DM2 and WR 12DM2, developed under the concept for "more compact, powerful and
convenient models", have been highly evaluated. However, the market is becoming fiercely competitive due to a
price war of the 9.6-V, 12-V, 14.4-V and 18-V impact driver/wrench series products. To address the severe
situation, we have developed the new high-performance impact driver/wrench series Models WH 12DMR and
WR 12DMR under the same concept as the current impact driver/wrench series. The new Models WH 12DMR
and WR 12DMR can take on the low-price competitors.
The performance level is in between the current Model WH 12DM2 and the competitors.
The cost is reduced by adoption of the new magnet and the like.
3. APPLICATIONS
•Tightening/loosening of small screws, tapping screws, wood screws, bolts, nuts, etc.
•Drilling into wood and various other materials (with use of optional accessory drill chuck adapter).
[Applicable Markets]
•Wood-product assembly: Tightening/loosening of wood screws
•Construction industry: Assembly of scaffolding, roofing, aluminum sashes, fencing, etc.; removal of plastic cones
from concrete forms, mounting/removal of form ties; drilling into the wood frames of concrete forms, etc.
•Manufacturing industry: Assembly work for automobiles, rolling stock, shipbuilding, agricultural machinery and
tools, industrial machines, steel furniture, etc.
•Utility industry: Assembly and installation of electric equipment, plumbing facilities, air conditioning (duct
assembly etc.), sanitary fixtures and various other facilities.
•Service industry: General repair work; installation of advertising aids, automobile repair, assembly of garages
and carports storage sheds, etc.
•Various other assembly, construction or repair facilities.
4. STANDARD EQUIPMENT
(1) 2BLGK specification: Two EB 1220BL batteries (NiCd, capacity 2.0 Ah), UC 18YG charger and case
(2) 2HLFK specification: Two EB 1226HL or EB 1230HL batteries (NiMH, capacity 2.6 Ah or 3.0 Ah), UC 14YFA charger
and case

--- 2 ---
5. SELLING POINTS
(1) Cordless impact driver Model WH 12DMR
Class-top tightening speed and
tightening torque 130 N•m
P: 113 N•m
Class-top short body 155 mm and lightweight 1.6 kg
P: 165 mm, 1.7 kg
High durability, dust resistance
and long service life
Common to the Model WH 12DM2
Advanced case
Replaceable carbon brushes
Common to the Model WH 12DM2
Convenient light equipped hook
Common to the Model WH 12DM2
Protector is standard.
Common to the Model WH 12DM2
Common to the Model WH 12DM2

--- 3 ---
(2) Cordless impact wrench Model WR 12DMR
Class-top short body 162 mm and lightweight 1.6 kg
P: 168 mm, 1.7 kg
Class-top tightening torque 160 N•m
P: 158 N•m
High durability, dust resistance
and long service life
Common to the Model WH 12DM2
Replaceable carbon brushes
Common to the Model WH 12DM2
Convenient light equipped hook
Common to the Model WH 12DM2
Protector is standard.
Common to the Model WH 12DM2
Advanced case
Common to the Model WH 12DM2

--- 4 ---
5-1. Selling Point Descriptions
Common selling points (Models WH 12DMR and WR 12DMR)
(1) High durability
Owing to the shift of demand from nails to screws and increased demand for long screws, impact drivers
having high heat resistance in continuous operation are much sought after. However, there are problems such
as heavy noise or vibration of the ball bearings and decrease in power if the impact drivers are used harshly in
dusty environments. In addition, higher strength and longer service life are required to continuously tighten
and loosen bolts in scaffolding and demolishing works. The Models WH 12DMR/WR 12DMR have high
durability, dust resistance and long service life in continuous operation as described below.
0
50
100
150
200
250
P
HITACHI WH 12DMR
Temperature ( C)
1 battery
2 batteries 3 batteries
Burnout
P: Smoking
Enhanced heat resistance of the motor
Example: When tightening M12 bolts continuously (Cycle of operation: 5-second impacting and 10-second
stopping, 3.0 Ah battery used)
The heat resistance comparison between the Models WH 12DMR/WR 12DMR and P is shown below.
The cooling efficiency is improved thanks to the powerful full-fledged large radial fan and the computer-
analyzed air ducts. Thus the Models WH 12DMR/WR 12DMR are protected from burnout due to long-time
continuous use and decrease in speed due to temperature rise.
1
Selling points of the Model WH 12DMR
Top-class tightening speed and torque 130 N.m (1320 kgf.cm, 1150 in-lbs.)
Although the Model WH 12DMR is equipped with an anisotropic bonded magnet that is cheaper than that of
the Model WH 12DM2, the performance is almost equivalent to the Model WH 12DM2 thanks to the large
hammer and the optimized impact timing. Comparison of measured data with the Model WH 12DM2 and
competitors is shown below.
Tightening time comparison
Figure 1 shows the time required for tightening a wood screw (5.3 mm dia. x 120 mm length) into a lauan
workpiece. (5 % higher than the Model WH 12DM2 and 5 % lower than P).
1

--- 5 ---
* Tightening time may vary depending on hardness of the workpiece, ambient temperature, characteristics
of the battery, etc.
Fig. 1 Tightening time comparison
Tightening torque comparison
Figure 2 shows the torque required for
tightening an M14 high-strength tension
bolt in 3 seconds with a hexagon socket
(40 mm long) (6% higher than P).
2
Fig. 2 Tightening torque comparison
HITACHI WH 12DMR
HITACHI WH 12DM2
5.0 sec.
Model (sec.)
4.7 sec.
5.2 sec.
612
814
4
210
Fast Slow
P
16
132
40
80
160
0
WH 12DM2
WH 12DMR
400 (347 in-lbs.)
800 (694 in-lbs.)
1200 (1042 in-lbs.)
Nm
120
1600 (1389 in-lbs.) 137
124
140
100
60
200 (174 in-lbs.)
1000 (868 in-lbs.)
600 (521 in-lbs.)
1400 (1215 in-lbs.)
kgf cm
20
P
Tightening torque
Selling points of the Model WR 12DMR
Powerful tightening torque 160 N•m {1630 kgf•cm, 1420 in-lbs.}
Although the Model WR 12DMR is equipped with an anisotropic bonded magnet that is cheaper than that of
the Model WR 12DM2, the performance is almost equivalent to the Model WR 12DM2 thanks to the large
hammer and the optimized impact timing. Comparison of measured data with the Model WR 12DM2 and
competitors is shown below.
The tightening torque is 5 % lower than the previous 12-V product Model WR 12DM2 and 5 % higher than P1.
The tightening torque is equivalent to P2.
The Model WR 12DMR is also mechanically strong thanks to the strong components to realize powerful
operation. Thus, the service life is 2 or 3 times longer than the competitors in spite of the compact body.
Comparison of measured data with the previous models and competitors is shown below.

--- 6 ---
Fig. 3
(1) Tightening torque comparison
Figure 3 shows the torque required for tightening an M16 F10T bolt in 3 seconds with a hexagon socket
(40 mm long). The tightening torque of the Model WR 12DMR is substantially lower than the previous model
(12 V) and equivalent to or more than P2.
* The data above are intended for reference purposes only because actual tightening torque will vary
depending on tightening conditions.
To describe the merit of high tightening torque, the comparison data are shown in Figure 4. Figure 4 shows
the time required for sinking a square washer into a wood workpiece.
Tightening torque
0
80
60
40
20
100
120
140
WR 12DM2
(12 V)
P1
(12 V)
kgf
cm
170
154
163
WR 12DMR
(12 V)
162
160
180
200
0
1800 (1562 in-lbs.)
2000 (1736 in-lbs.)
N
m
P2
(12 V)
400 (347 in-lbs.)
800 (694 in-lbs.)
1200 (1042 in-lbs.)
1600 (1389 in-lbs.)
200 (174 in-lbs.)
1000 (868 in-lbs.)
600 (521 in-lbs.)
1400 (1215 in-lbs.)
Fig. 4
(3) Sinking time comparison (square washers)
Figure 4 shows the time required for tightening an M12 bolt into a pine laminated lumber of 105 mm square
until the square washers at both sides are sunk into the lumber by 1.3 mm respectively.
The Model WR 12DMR can tighten strap bolts and corner bracings (used in Japanese wooden buildings)
speedily as it can sink washers into a workpiece quickly.
*The data above are intended for reference purposes only because actual time required for sinking
washers will vary depending on tightening conditions.
0
4
2
6
10
8
2.7
3.5
3.0
WR 12DM2
(12 V)
2.9
WR 12DMR
(12 V)
P1
(12 V)
P2
(12 V)
Tightening time (sec)

--- 7 ---
6. SPECIFICATIONS
6-1. Specifications
Model Cordless Impact Driver
WH 12DMR
Capacity
Item
Cordless Impact Wrench
WR 12DMR
Small screw M4 --- M8 (5/32" --- 5/16")*1
Ordinary bolt M5 --- M12 (3/16" --- 15/32")
High-strength bolt M5 --- M10 (3/16" --- 25/64")
Ordinary bolt M6 --- M16 (1/4" --- 5/8")
High-strength bolt M6 --- M12 (1/4" --- 15/32")
Tightening torque 130 N•m (1320 kgf •cm, 1150 in-lbs.)*2160 N•m (1630 kgf
•
cm, 1420 in-lbs.)*3
Tip condition 6.35 mm (1/4") Bit holder 12.7 mm (1/2") Square drive
9.5 mm (3/8") Square drive
Type of motor Fan cooled rare-earth magnet motor
Enclosure Main body: Polyamide resin + elastomer •••••• Housing
Aluminum alloy die casting ••••••••• Hammer case
Elastomer ••••••••••••••••••••••••••••••••• Protector
Storage battery: ABS resin (black)
Charger: ABS resin (black)
Type of switch Trigger switch with forward/reverse changeover pushing button (with brake)
Handle configuration T-type
No-load rotational speed 0 --- 2,600 /min
Impact rate 0 --- 3,200 /min
Main body 1.6 kg (3.5 lbs.) (Includes battery)*4
Battery 0.68 kg (1.5 lbs.)
Overall length x height 155 mm (6-7/64") x 226 mm (8-29/32")
Center height 26.5 mm (1-3/64")
Battery
(Type EB 1220BL)
Sealed cylindrical nickel-cadmium batteries
Nominal voltage: DC 12V
Nominal life: Charging/discharging approximately 300 cycles
(in the case of Model UC 18YG)
Nominal capacity: 2.0 Ah
12.7 mm (1/2") square drive .....
162 mm (6-3/8") x 226 mm (8-29/32")
9.5 mm (3/8") square drive .....
159 mm (6-1/4") x 226 mm (8-29/32")
Battery
(Type EB 1226HL/
EB 1230HL)
Sealed cylindrical nickel-metal hydride batteries
Nominal voltage: DC 12V
Nominal life: Charging/discharging approximately 500 cycles
(in the case of Model UC 14YFA)
Nominal capacity: 2.6 Ah/3.0 Ah
Weight
Charger
(Model UC 14YFA)
Charger power source: single-phase AC, 50/60 Hz
Voltage: Depending on the order specification
Power input: 56 W
Charging system: Constant current charge with feedback control
Overcharge protection system: (1) Battery voltage detection ( 2V system)
Battery temperature detection (dT/dt system) for
Ni-MH battery
(2) Battery surface temperature detection
(thermistor)
(3) 120-minute timer
Output voltage: 7.2 V --- 14.4 V
Output current: 2.6 A
Charging time: Approx. 50 minutes (for type EB 1220BL battery at 20 ûC)
Approx. 60 minutes (for type EB 1226HL battery at 20 ûC)
Approx. 70 minutes (for type EB 1230HL battery at 20 ûC)
Product weight: 0.6 kg
Operable ambient temperature range: 0 ûC --- 40 ûC
The maximum allowable temperature of the EB 1220BL type battery is 55 ûC and the
EB 1226HL or EB 1230HL type battery is 45 ûC.

--- 8 ---
Charger
(Model UC 18YG)
Overcharge prevention circuit:
A thermostat monitos the surface temperature of the battery and, on detecting the
temperature rise which occurs on completion of charging, automatically turns off the
unit to prevent the battery from overcharge.
Iutput capacity: 70 W
Indication method: Pilot lamp indicator of battery charging
Function: On.............................................................................. During charging
Off.............................................................................. Charging completed
*1: In the case of tapping screws and wood screws, a minimum of M3 (1/8") is possible.
*2: This torque is based on tightening an M14 (9/16") bolt (strength grade: 12.9) for 3 seconds with a hexagonal socket.
*3: This torque is based on tightening an M16 (5/8") bolt (F10T) for 3 seconds with a hexagonal socket.
*4: Main body does not include accessory tools and hook (hexagonal bit etc.).
Prior to charging
During charging
Charging completed
Charging not possible
High battery
temperature
Blinks
Lit
Blinks
Flickers
Lit
0.5 sec ON, 0.5 sec OFF
Stays ON constantly
0.5 sec ON, 0.5 sec OFF
0.1 sec ON, 0.1 sec OFF
Stays ON constantly
Pilot lamp indications (Model UC 14YFA)
Red pilot lamp
remains lit or flashes.
Green pilot lamp is lit.
Storage battery or charger
is faulty.
Charging not possible
because storage battery
temperature is too high.
NOTE: The Model UC 18YG
charger is exclusive to
NiCad batteries.

--- 9 ---
6-2. Optional Accessories
(1) Optional accessories for the Model WH 12DMR
•Plus driver bit
50 mm (2")
Bit No.
No. 2
No. 3
Code No.
992671
992672
•Hexagon socket
L
B
Stamped figures
9961778 (5/16")65 (2-9/16")8
Stamped figures
5 mm Hexagon socket
Part name L
(mm)
B
(mm) Code No.
98532910 (3/8")65 (2-9/16")106 mm Hexagon socket
99617812 (15/32")65 (2-9/16")125/16" Hexagon socket
99617913 (1/2")65 (2-9/16")138 mm Hexagon socket
99618014 (9/16")65 (2-9/16")1410 mm Hexagon socket (small type)
99618116 (5/8")65 (2-9/16")1610 mm Hexagon socket
99618217 (21/32")65 (2-9/16")1710 mm Hexagon socket
99619721 (53/64")166 (6-17/32")211/2" Hexagon long socket
•Woodworking drill bit (Code No. 959183)
14 mm dia.
(35/64")
83 mm (3-17/64")
•Drill chuck adaptor set (Code No. 996195)
The drill chuck adaptor set permits mounting of various types of locally-available drill bits for a variety of drilling
operations.

--- 10 ---
(2) Optional accessories for the Model WR 12DMR
•Each dimension and applicable bolt for each hexagon socket
10 mm
12 mm
13 mm
14 mm
17 mm
19 mm
21 mm
22 mm
24 mm
40 (1-9/16")
40 (1-9/16")
40 (1-9/16")
40 (1-9/16")
32 (1-1/4")
34 (1-11/32")
36 (1-13/32")
40 (1-9/16")
40 (1-9/16")
B
B
B
B
C
C
D
D
D
10 (3/8")
12 (15/32")
13 (1/2")
14 (9/16")
17 (21/32")
19 (23/32")
21(53/64")
22 (7/8")
24 (15/16")
W 5/16"
W 3/8"
W 7/16"
W 1/2"
M 12 (15/32")
944291
873632
873539
873540
873536
873624
873626
873627
873629
Hexagon socket
12.7 mm
(1/2")
Square
drive
dimension
Sq
Part
name
Code
No.
Nominal diameter of applicable bolts Dihedral
width
H (mm)
Shape
Socket primary dimensions (mm)
L
M 6 (1/4")
M 8 (5/16")
M 10 (3/8")
M 12 (15/32")
M 14 (9/16")
M 16 (5/8")
M 8 (5/16")
M 10 (3/8")
M 12 (15/32")
M 14 (9/16")
M 16 (5/8")
M 18 (23/32")
L1
8 (5/16")
8 (5/16")
9 (11/32")
9 (11/32")
8 (5/16")
9 (11/32")
10 (3/8")
14 (9/16")
15 (9/16")
D1
18 (23/32")
20 (25/32")
25 (1")
25 (1")
28 (1-3/32")
28 (1-3/32")
32 (1-1/4")
35 (1-3/8")
38 (1-1/2")
ISO
(Ordinary)
ISO
(Small type)
Inch
screw
ISO
(High-
strength)
Shape B Shape C Shape D
Shape B Shape D
•Each dimension and applicable bolt for each long socket

--- 11 ---
12 mm
13 mm
14 mm
17 mm
17 mm
19 mm
19 mm
21 mm
21 mm
21 mm
22 mm
24 mm
34 (1-11/32")
34 (1-11/32")
34 (1-11/32")
34 (1-11/32")
57 (2-1/4")
34 (1-11/32")
57 (2-1/4")
34 (1-11/32")
57 (2-1/4")
107 (4-7/32")
34 (1-11/32")
34 (1-11/32")
52 (2-3/64")
52 (2-3/64")
52 (2-3/64")
52 (2-3/64")
75 (2-15/16")
52 (2-3/64")
75 (2-15/16")
52 (2-3/64")
75 (2-15/16")
125 (4-47/51")
52 (2-3/64")
52 (2-3/64")
B
B
B
B
B
B
B
D
D
D
D
D
12 (15/32")
13 (1/2")
14 (9/16")
17 (21/32")
17 (21/32")
19 (23/32")
19 (23/32")
21 (53/64")
21 (53/64")
21 (53/64")
22 (7/8")
24 (15/16")
W 5/16"
W 3/8"
W 3/8"
W 7/16"
W 7/16"
W 1/2"
W 1/2"
W 1/2"
M 12 (15/32")
955138
955139
955140
955141
955149
955142
955150
955143
955151
991480
955144
955146
Long socket
12.7 mm
(1/2")
Square
drive
dimension
Sq
Part
name
Code
No.
Nominal diameter of applicable bolts Dihedral
width
H (mm)
Shape
Socket primary dimensions (mm)
LL1
20 (25/32")
20 (25/32")
20 (25/32")
24 (15/16")
24 (15/16")
24 (15/16")
24 (15/16")
24 (15/16")
24 (15/16")
24 (15/16")
24 (15/16")
25 (63/64")
D1
20 (25/32")
21.5 (53/64")
22 (7/8")
25 (1")
25 (1")
28 (1-3/32")
28 (1-3/32")
31 (1-7/32")
31 (1-7/32")
31 (1-7/32")
32.5 (1-9/32")
34 (1-11/32")
L2
ISO
(Ordinary)
ISO
(Small type)
Inch
screw
ISO
(High-
strength)
M 8 (5/16")
M 10 (3/8")
M 10 (3/8")
M 12 (15/32")
M 12 (15/32")
M 14 (9/16")
M 16 (5/8")
M 8 (5/16")
M 10 (3/8")
M 12 (15/32")
M 12 (15/32")
M 14 (9/6")
M 14 (9/6")
M 16 (5/8")
M 18 (23/32")
•Bit adaptor (Code No. 991476)
6.35 mm (1/4") 45 mm (1-25/32")
13.5 mm dia.
(17/32")
12.7 mm (1/2")
• Extension bar [Overall length 100 mm (3-15/16") ] (Code No. 873633)
• Universal joint (Code No. 992610)
• Socket ass'y for duct
• EW-14R corner attachment (Code No. 9329-9001)
Part name Overall length
(mm) Code No.
Plus hd.
driver bit
No. 2
45 (1-25/32") 955229
70 (2-3/4") 955654
45 (1-25/32") 955230
70 (2-3/4") 955655
Plus hd.
driver bit
No. 3
Dihedral width of
applicable bolts Code No.
12 (15/32") 993658
13 (1/2") 992613
14 (9/16") 992615

--- 12 ---
M 4 --- M 8
(5/32" --- 5/16")
7. COMPARISONS WITH SIMILAR PRODUCTS
7-1. Specification Comparisons (Cordless Impact Driver)
HITACHI
Maker
ModelItem
Catalog specifications
Capacity
Small screw
Ordinary bolt
High-strength bolt
Max. tightening torque*2N•m
No-load rotation speed /min
Impact rate /min
Main body weight kg
Max. tightening torque N•m
Measured figures
No-load rotation speed /min
Impact rate /min
Overall length x height mm
Center height mm
Main body weight kg
No-load sound pressure level
dB(A)
Tool tip mounting system
Type of switch
Type of motor
Voltage
Current
Battery
V
A
Type
Nominal capacity Ah
Nominal voltage V
Ambient temperature ûC
Model
Power input capacity VA
Recharging voltage V
Standard accessories
Charger
*1
*3
*4
*3
P
112.6
(1150 kgf
•
cm, 1000 in-lbs.)
0 --- 2,400
0 --- 3,000
1.7 (3.75 lbs.)
124
(1265 kgf
•
cm, 1095 in-lbs.)
0 --- 2,410
0 --- 2,810
165 x 233
(6-1/2" x 9-11/64")
29 (1-9/64")
1.7 (3.75 lbs.)
76
Driver chuck
Variable speed switch
with forward/reverse
changeover lever
DC magnet
12
29
DW9071
12
DW9107
7.2 --- 14.4
•Plastic tool case
•Charger
1.7
*1: In the case of tapping screws and wood screws, a minimum of M3 (1/8") is possible.
*2: Max. tightening torque is based on tightening an M14 (9/16") bolt (strength grade: 12.9) for 3 seconds with a hexagon
socket.
*3: Main body weight does not include accessory tools and hook (hexagon bit etc.).
*4: Max. tightening torque is based on tightening an M14 (9/16") bolt (strength grade: 12.9) for 3 seconds with a hexagon
socket.
M 4 --- M 8
(5/32" --- 5/16")
WH 12DMR
M 5 --- M 12
(3/16" --- 15/32")
M 5 --- M 10
(3/16" --- 3/8")
130
(1320 kgf
•
cm, 1150 in-lbs.)
0 --- 2,600
0 --- 3,200
1.6 (3.5 lbs.)
132
(1340 kgf
•
cm, 1170 in-lbs.)
0 --- 2,480
0 --- 2,680
155 x 226
(6-7/64" x 8-29/32")
26.5 (1-3/64")
1.69 (3.7 lbs.)
70
Driver chuck
Variable speed switch
with forward/reverse
changeover lever
DC magnet
12
28
EB 1220BL, EB 1230HL
or EB 1226HL
EB 1220BL: 2.0
EB 1226HL: 2.6
EB 1230HL: 3.0
12
0 --- 40
UC 14YFA or UC 18YG
UC 14YFA: 56
UC 18YG: 70
UC 14YFA: 7.2 --- 14.4
UC 18YG: 7.2 --- 18
•Plastic tool case
•Charger
(UC 14YFA or UC 18YG)
WH 12DM2
M 5 --- M 12
(3/16" --- 15/32")
M 5 --- M 10
(3/16" --- 3/8")
135
(1375 kgf•cm, 1190 in-lbs.)
0 --- 2,600
0 --- 3,200
1.6 (3.5 lbs.)
137
(1400 kgf
•
cm, 1220 in-lbs.)
0 --- 2,600
0 --- 2,920
155 x 226
(6-7/64" x 8-29/32")
26.5 (1-3/64")
1.67 (3.7 lbs.)
70
Driver chuck
Variable speed switch
with forward/reverse
changeover lever
DC magnet
12
31
EB 1220BL or
EB 1230HL
EB 1220BL: 2.0
EB 1230HL: 3.0
12
0 --- 40
UC 14YF2 or UC 14YFA
UC 14YF2: 44
UC 14YFA: 56
7.2 --- 14.4
•Plastic tool case
•Charger
(UC 14YF2 or UC 14YFA)
*1

--- 13 ---
7-2. Specification Comparisons (Cordless Impact Wrench)
*1: Max. tightening torque is based on tightening an M16 (5/8") bolt (F10T) for 3 seconds with a hexagon socket.
*2: Max. tightening torque is based on tightening an M14 (9/16") bolt (strength grade: 12.9) for 3 seconds with a hexagon
socket.
*3: Main body weight does not include accessory tools and hook (hexagon bit etc.).
M 6 --- M 16
(1/4" --- 5/8")
HITACHI
Maker
ModelItem
Catalog specifications
Capacity
Ordinary bolt
High-strength bolt
Max. tightening torque N•m
No-load rotation speed /min
Impact rate /min
Main body weight kg
Max. tightening torque N•m
Measured figures
No-load rotation speed /min
Impact rate /min
Overall length x height mm
Center height mm
Main body weight kg
No-load sound pressure level
dB(A)
Tool tip mounting system
Type of switch
Type of motor
Voltage
Current
Battery
V
A
Type
Nominal capacity Ah
Nominal voltage V
Ambient temperature ûC
Model
Power input capacity VA
Recharging voltage V
Standard accessories
Charger
*1
*3
P1
135.6 *2
(1380 kgf•cm, 1200 in-lbs.)
0 --- 2,400
0 --- 3,000
1.68 (3.7 lbs.)
154
(1570 kgf•cm, 1360 in-lbs.)
0 --- 2,410
0 --- 2,810
168 x 233
(6-39/64" x 9-11/64")
29 (1-9/64")
1.73 (3.8 lbs.)
76
Hog ring
Variable speed
switch with
forward/reverse
changeover lever
DC magnet
12
22
1222
12
DC1411
7.2 --- 14.4
2.0
M 6 --- M 16
(1/4" --- 5/8")
WR 12DMR
M 6 --- M 12
(1/4" --- 15/32")
160 *1
(1630 kgf
•
cm, 1420 in-lbs.)
0 --- 2,600
0 --- 3,200
1.6 (3.5 lbs.)
163
(1660 kgf
•
cm, 1440 in-lbs.)
0 --- 2,480
0 --- 2,680
26.5 (1-1/64")
1.69 (3.7 lbs.)
70
9.5 mm (3/8") .. Retaining ring
12.7 mm (1/2") ... Plunger
Variable speed switch
with forward/reverse
changeover lever
DC magnet
12
28
EB 1220BL, EB 1230HL
or EB 1226HL
EB 1220BL: 2.0
EB 1226HL: 2.6
EB 1230HL: 3.0
12
5 --- 40
UC 14YFA or UC 18YG
UC 14YFA: 56
UC 18YG: 70
UC 14YFA: 7.2 --- 14.4
UC 18YG: 7.2 --- 18
•
Plastic tool case
•
Charger
(UC 14YFA or UC 18YG)
WR 12DM2
M 6 --- M 12
(1/4" --- 15/32")
165 *1
(1685 kgf
•
cm, 1460 in-lbs.)
0 --- 2,600
0 --- 3,200
1.6 (3.5 lbs.)
170
(1735 kgf
•
cm, 1500 in-lbs.)
0 --- 2,600
0 --- 3,240
162 x 226
(6-3/8" x 8-29/32")
26.5 (1-1/64")
1.68 (3.7 lbs.)
70
Plunger
Variable speed switch
with forward/reverse
changeover lever
DC magnet
12
31
EB 1220BL or
EB 1230HL
EB 1220BL: 2.0
EB 1230HL: 3.0
12
5 --- 40
UC 14YF2 or UC 14YFA
UC 14YF2: 44
UC 14YFA: 56
7.2 --- 14.4
•
Plastic tool case
•
Charger
(UC 14YF2 or UC 14YFA)
Tip condition
9.5 mm (3/8") square
drive or 12.7 mm (1/2")
square drive
12.7 mm (1/2") square
drive
9.5 mm (3/8"):
160 x 226 (6-19/64" x 8-29/32")
12.7 mm (1/2"):
162 x 226 (6-3/8" x 8-29/32")
•
Plastic tool
case
•
Charger
9.5 mm (3/8")
square drive
P2
158.7
(1610 kgf•cm, 1400 in-lbs.)
0 --- 2,400
0 --- 3,000
1.7 (3.75 lbs.)
162
(1653 kgf•cm, 1429 in-lbs.)
0 --- 2,410
0 --- 3,120
168 x 233
(6-39/64" x 9-11/64")
29 (1-9/64")
1.75 (3.9 lbs.)
76
12.7 mm (1/2")
square drive
Plunger
Variable speed
switch with
forward/reverse
changeover lever
DC magnet
12
29
DW9071
12
2.0
DW9107
7.2 --- 14.4
•
Plastic tool
case
•
Charger

--- 14 ---
7-3. Tightening Torque
7-3-1. Tightening torque characteristic comparisons
WH 12DM2
200 (174 in-lbs.)
0123
400 (347 in-lbs.)
600 (521 in-lbs.)
800 (694 in-lbs.)
1000 (868 in-lbs.)
WH 12DMR
1200 (1042 in-lbs.) 120
100
80
20
40
60
0
0
0
140
1400 (1215 in-lbs.)
P
kgf cm N
m
Test conditions
Bolt: M14 x 50 mm, high-strength bolt
Steel plate: SS34P
Thickness 25 mm
Accessory tool: Hexagon socket
(length: 40 mm,
width across flat: 19 mm)
(2) Impact wrench
Test conditions
Bolt: M16 x 55 mm (5/8" x 2-5/32") (F10T)
Steel plate: Mild steel
Thickness 25 mm
Accessory tool: Hexagon socket ass'y
(1) Impact driver
WR 12DM2
0123
P1
120
100
80
20
40
60
0
0
140
200
180
160
WR 12DMR, P2
200 (174 in-lbs.)
400 (347 in-lbs.)
600 (521 in-lbs.)
800 (694 in-lbs.)
1000 (868 in-lbs.)
1200 (1042 in-lbs.)
0
1400 (1215 in-lbs.)
kgf
cm N
m
1600 (1389 in-lbs.)
1800 (1562 in-lbs.)
2000 (1763 in-lbs.)

--- 15 ---
7-3-2. Screw diameter and appropriate tightening torque
Generally speaking, the appropriate tightening torque for a screw can be determined by the strength grade of the
screw and the material tightened. Tables 1 and 2, and Fig. 5 below list data relative to the strength grade of
various screws and the appropriate tightening torque. For further reference, appropriate tightening torque is
calculated with the following formula. Study and use this formula for accurate selection of tightening torque.
T=k•d•p
T: Appropriate tightening torque (kgf•cm)
d: Nominal diameter for the screw (mm)
p: Recommended axial tightening force to be applied to the screw (kgf)
p=rated axial stress (kgf/cm2) x 0.8 x effective sectional area of the thread (mm2)
k: Torque coefficient (0.17)
•Strength grade and rated axial stress of threads
Strength grade
Rated axial stress (kgf/mm2)
Material
Heat treatment
4.8 6.8 8.8 12.9
29.1 43.7 58.2 95
Mild steel Alloy steel including Ni, Mn, Cr, etc.
None Processed-hard material
•Diameter and effective sectional areas of threads
Kind of thread (x pitch)
Effective sectional area
of thread (mm2)
M5 x 0.8 mm
(3/16")
14.2
M6 x 1 mm
(1/4")
20.1
M8 x 1.25 mm
(5/16")
36.6
M10 x 1.5 mm
(3/18")
58.0
M12 x 1.75 mm
(15/32")
84.3
M14 x 2 mm
(9/16")
115
•Thread diameter and appropriate tightening torque
Table 1
Table 2
M16 x 2 mm
(5/8")
157
Strength grade 12.9
(high-strength bolt)
Strength grade 8.8
(high-strength bolt)
Strength grade 6.8
(ordinary bolt)
Strength grade 4.8
(ordinary bolt)
0
16
(5/8")
6
(1/4")
8
(5/16")
10
(3/8")
12
(15/32")
14
(9/16")
mm
500
(434 in-lbs.)
1000
(868 in-lbs.)
2500
(2170 in-lbs.)
kgf
.
cm
0
50
250
200
150
100
300
N
.
m
1500
(1302 in-lbs.)
2000
(1736 in-lbs.)
3000
(2604 in-lbs.)
Thread diameter
Appropriate tightening torque
Fig. 5

--- 16 ---
•Model WH 12DMR
Tightening time: sec.
(Steel plate thickness
t = 10 mm)
200
(174 in-lbs.)
0123
400
(347 in-lbs.)
600
(521 in-lbs.)
800
(694 in-lbs.)
1000
(868 in-lbs.)
M10 x 30
Tightening torque
High-strength bolt
00
20
40
60
80
100
Tightening time: sec.
(Steel plate thickness
t = 25 mm)
0123
Tightening time: sec.
(Steel plate thickness
t = 25 mm))
M14 x 50
High-strength bolt
Ordinary bolt
0123
M12 x 45
Tightening torque
High-strength bolt
00
20
40
60
80
100
Ordinary bolt
Ordinary bolt
120
140
1200
(1042 in-lbs.)
1400
(1215 in-lbs.)
0
20
40
60
80
100
120
140
200
(174 in-lbs.)
400
(347 in-lbs.)
600
(521 in-lbs.)
800
(694 in-lbs.)
1000
(868 in-lbs.)
Tightening torque
0
1200
(1042 in-lbs.)
1400
(1215 in-lbs.)
200
(174 in-lbs.)
400
(347 in-lbs.)
600
(521 in-lbs.)
800
(694 in-lbs.)
1000
(868 in-lbs.)
kgf cm
Nm
kgf cm
Nm
kgf cm
Nm
7-3-3. Bolt tightening torque characteristics
Figures. 6-1 and 6-2 show relationships between time and tightening torque for individual bolt types and sizes.
While the data are useful for handy reference, actual tightening torque will vary depending on tightening
conditions and other variables. For details, please refer to Para. 8-3, "Tightening Torque Variation".
NOTE
•The term "tightening time" indicates the impact time after the lower surface of the bolt has come in contact with
the material into which it is being tightened.
•In the tightening conditions shown in Figs. 6-1 and 6-2, the screws are being tightened directly into a steel
plate; accordingly, the torque goes up very abruptly in comparison with ordinary bolt tightening conditions.
Fig. 6-2
Bolt
Nut
Steel plate
thickness: t
* The following bolts were utilized:
Ordinary bolt; strength grade 4.8
High-strength bolt; strengh grade
12.9
Strength grade is read as follows:
4.8
Yield point or durable force:
(45,500 psi)
Tensile strength of the bolt:
(56,900 psi)
•Model WR 12DMR
Tightening time: sec.
(Steel plate thickness
t = 10 mm)
500
(434 in-lbs.)
0123
1000
(868 in-lbs.)
1500
(1302 in-lbs.)
2000
(1763 in-lbs.)
M10 x 30
Tightening torque
High-strength bolt
00
50
100
150
200
Ordinary bolt
Tightening time: sec.
(Steel plate thickness
t = 25 mm)
0123
M12 x 45
Tightening torque
High-strength bolt
00
50
100
150
200
Ordinary bolt
Tightening time: sec.
(Steel plate thickness
t = 25 mm)
0123
M14 x 50
Tightening torque
High-strength bolt
00
50
100
150
200
Ordinary bolt
500
(434 in-lbs.)
1000
(868 in-lbs.)
1500
(1302 in-lbs.)
2000
(
1763 in-lbs.)
500
(434 in-lbs.)
1000
(868 in-lbs.)
1500
(1302 in-lbs.)
2000
(
1763 in-lbs.)
kgf cm
Nm
kgf cm
Nm
kgf cm
Nm
Fig. 6-1

--- 17 ---
HITACHI WH 12DMR
HITACHI WH 12DM2
5.0 sec.
Model sec.
4.7 sec.
210
412
614 816 18
Fast Slow
20
5.2 sec.
P
HITACHI WH 12DMR
HITACHI WH 12DM2
2.6 sec.
Model sec.
2.4 sec.
24
13
Fast Slow
5
2.6 sec.
P
HITACHI WH 12DMR
HITACHI WH 12DM2
1.7 sec.
Model sec.
1.6 sec.
24
13
Fast Slow
5
1.7 sec.
P
7-4. Tightening Time
The tightening speed is almost equivalent to the Model WH 12DM2 that is fastest in the class. Tightening time
comparison is shown below. The data below are intended for reference purposes only because actual tightening
time may vary depending on hardness of the workpiece, ambient temperature, characteristics of the battery, etc.
2 Wood screw 4.5 mm dia. x 90 mm length, hemlock spruce
3 Wood screw 4.2 mm dia. x 75 mm length, hemlock spruce
1 Wood screw 5.3 mm dia. x 120 mm length, lauan