Hitachi WR 12DH Manual

POWER TOOLS
TECHNICAL DATA
AND
SERVICE MANUAL
CORDLESS IMPACT DRIVER
WH 12DH
CORDLESS IMPACT WRENCH
WR 12DH
SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT
LIST No. F829, 830 Mar. 1999
W
MODEL
WH 12DH
WR 12DH
WH 12DH WR 12DH

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
C MAKITA 6914D
WH 12DH
Symbol Utilized Competitor
Company Name Model Name
C MAKITA 6911D
WR 12DH

Page
CONTENTS
[ Business Section ]
1. PRODUCT NAME •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 1
2. MARKETING OBJECTIVE ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 1
3. APPLICATIONS ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 1
4. PRODUCT DESIGNATION IN MODEL NAME •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 1
5. SELLING POINTS •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 2
5-1. Selling Point Descriptions ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 3
6. SPECIFICATIONS •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 6
6-1. Specifications ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 6
6-2. Optional Accessories •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 7
7. COMPARISONS WITH SIMILAR PRODUCTS ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 11
7-1. Specification Comparisons (Cordless Impact Driver) ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 11
7-2. Specification Comparisons (Cordless Impact Wrench) •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 12
7-3. Tightening torque •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 13
7-4. Number of Screws or Bolts Driven ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 17
8. PRECAUTIONS IN SALES PROMOTION •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 19
8-1. Safety Instructions •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 19
8-2. Tightening Torque Inspection Prior to Operation •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 21
8-3. Tightening Torque Variation ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 21
8-4. Suggestions and precautions for the Efficient Use of the Charger •••••••••••••••••••••••••••••••••••••••••••• 23
9. OTHER PRECAUTIONS •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 24
[ Service section ]
10. REPAIR GUIDE •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 25
10-1. Precautions in Disassembly and Reassembly ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 25
10-2. Precautions in Disassembly and Reassembly of Battery Charger ••••••••••••••••••••••••••••••••••••••••••• 30
11. STANDARD REPAIR TIME (UNIT) SCHEDULES •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 31
[ Appendix ]
Assembly Diagram for WH 12DH ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 32
Assembly Diagram for WR 12DH ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 35

--- 1 ---
1. PRODUCT NAME
Hitachi Cordless Impact Driver, Model WH 12DH
Hitachi Cordless Impact Wrench, Model WR 12DH
2. MARKETING OBJECTIVE
The current Hitachi cordless impact driver series has provided excellent workability thanks to their performance
that produces no reaction force in tightening screws and bolts and also no damage to the screw heads. Now, we
bring out the new cordless impact driver Model WH 12DH developed based on the previous Model WH 12DC.
The Model WH 12DH has more compact body, better tightening performance and longer service life than those of
the previous model, and is equipped with a replaceable carbon brush motor. The new cordless impact wrench
Model WR 12DH is also brought out. The Model WR 12DH has more compact and lightweight body than that of
the previous Model WH 12D. The construction of the Model WR 12DH is the same as that of the Model
WH 12 DH except the anvil (K) ass'y and the hammer case.
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. PRODUCT DESIGNATION IN MODEL NAME
To differentiate impact wrenches clearly from impact drivers, the "WH" formerly used for both impact drivers and
impact wrenches will be "WR" for impact wrenches from now on.
(1) Cordless impact driver
1. Type 2. Capacity 3. Essential division 4. Optional division
WH 12 D H
Impact driving Ordinary bolt: M12 Cordless Order of release
(Wrenching Hammer)
(2) Cordless impact wrench
1. Type 2. Capacity 3. Essential division 4. Optional division
WR 12 D H
Impact driving High-strength bolt: M12 Cordless Order of release
(Wrenching Revolving-bolt)

--- 2 ---
5. SELLING POINTS
Rare-earth magnet motor
Strong fastening torque
1,000 kgf•cm (98 N•m, 72 ft-lbs)
6.35 mm (1/4") Hex. drive
Cordless Impact Driver
WH 12DH
Cordless Impact Wrench
WR 12DH
Optional socket
Variable speed reversible
switch with electric brake
EB 12B (2.0 Ah) / EB 12H (2.2 Ah) Battery
for longer use per charge
Strong fastening torque
1,200 kgf•cm (117.6 N•m, 86.4 ft-lbs)
Compact body and lower
center height
12.7 mm (1/2") Square drive
180 mm (7-1/8")
26 mm
(1-1/64")
176 mm (6-15/16")
26 mm (1-1/64")
Compact and well-balanced body
for less-fatigue
Higher rotation speed/min. and
higher blows/min. for high power
and faster fastening
Improved motor performance
Replaceable carbon brushes for longer motor life
Fan cooled rare-earth magnet motor
Generates the same high torque at both forward & reverse modes
Rare-earth magnet motor
Replaceable
carbon brushes

--- 3 ---
HITACHI WH 12DH
HITACHI WH 12DC
C
12.3 sec
Model 5 10 15 20 sec
17.0 sec
12.5 sec
HITACHI WH 12DH
HITACHI WH 12DC
C
4.8 sec
Model 5 10 15 20 sec
6.5 sec
4.8 sec
HITACHI WH 12DH
HITACHI WH 12DC
C
0.85 sec
Model 0.2 0.4 0.6 0.8 1 sec
1.1 sec
0.87 sec
HITACHI WH 12DH
HITACHI WH 12DC
C
2.3 sec
Model 1 2 3 4 sec
2.6 sec
2.5 sec
5-1. Selling Point Descriptions
(1) Faster tightening speed
The Model WH 12DH provides faster driving speed than the previous model thanks to the high power rare-
earth magnet motor and the higher moment of inertia of the hammer. The comparisons with the previous
Model WH 12DC and maker C's model are shown below.
1 Tightening time (sec) (Wood screw 5.5 mm dia. x 120 mm length, hemlock spruce)
2 Tightening time (sec) (Wood screw 4.2 mm dia. x 90 mm length, hemlock spruce)
3 Tightening time (sec) (Wood screw 3.8 mm dia. x 20 mm length, lauan)
4 Tightening time (sec) (Teks screw 4 mm dia. x 13 mm length, SPCC 1.6 t)

--- 4 ---
Weight
L
A
B
C
Overall length
Center height
Switch position
Grip perimeter
Catalog weight
Actual weight
Item Model WH 12DH WH 12DC WR 12DH WH 12D
176
(6-15/16") 198
(7-25/32") 180 (7-1/8") 230 (9")
26
(1-1/64") 26
(1-1/64") 26 (1-1/64") 33.5 (1-15/16")
43
(1-11/16") 43
(1-11/16") 43 (1-11/16") 46.5 (1-25/32")
125
(4-29/32") 125
(4-29/32") 125 (4-29/32") 128 (5-1/32")
1.7
(3.7 lbs) 1.7
(3.7 lbs) 1.7 (3.7 lbs) 2.3 (5.1 lbs)
1.73
(3.81 lbs) 1.73
(3.81 lbs) 1.73 (3.81 lbs) 2.39 (5.31 lbs)
(2) Compact
L: 176 mm (6-15/16")
WH 12DH
A: Center hight 26 mm 43 mm B: Switch position
C: Grip perimeter
mm
mm
mm
mm
kg
kg
(3) Improved motor performance
The Models WH 12DH and WR 12DH are compact and have high power thanks to the rare-earth magnet
motor. Furthermore, these models have better heat resistance because the built-in fan enhances cooling
efficiency. Their motors have replaceable carbon brushes, and the service life of the carbon brush has been
extended by increasing its volume (by about 30 % compared to our previous model) and making seven slots in
a motor armature core.

--- 5 ---
Model WH 12DH
Tightening torque
(M12 high-strength bolt, 3 sec tightening)
Voltage 12 V
(EB 12 type battery)
1,000 kgf•cm
(98 N•m, 72 ft-lbs)
9.6 V
(EB 9 type battery)
800 kgf•cm
(78.5 N•m, 57.6 ft-lbs)
Model WR 12DH
Tightening torque
(M12 high-strength bolt, 3 sec tightening)
Voltage 12 V
(EB 12 type battery)
1,200 kgf•cm
(117.6 N•m, 86.4 ft-lbs)
9.6 V
(EB 9 type battery)
950 kgf•cm
(93.1 N•m, 68.4 ft-lbs)
Fig. 1 Fig. 2 Fig. 3
(4)Construction of replaceable carbon brushes
The carbon brush can be easily removed from the motor with a flat-blade screwdriver as shown in Fig. 2 and
can also be easily and securely mounted to the motor by hanging the claw of the carbon brush on the
connecting portion at the outside of the brush tube.
Claw of
carbon brush Collar of
carbon brush
Connecting portion at the
outside of brush tube
(5) Safe handle shape
Compared with the previous WH 12DC, the housing of the Model WH 12DH produces no clearance caused by
vibration because grips (R) and (F) (made of rubber) are provided at the juncture of the handle and the
housing is secured with two screws at the center of the handle to prevent the operator's hand from being
pinched. Furthermore, the rear portion of the housing is shaped upward not to interfere with the base of the
operator's thumb.
(6) 9.6 V Battery is also available.
As the 9.6 V battery (EB 9S type) is popular in the market, it is a strong selling point that both the Models WH
12DH and WR 12DH can also use this battery. The following table shows that the tightening torque is a little
lower because of a lower voltage, but there is little harm in operation.

--- 6 ---
6. SPECIFICATIONS
6-1. Specifications
Model Cordless Impact Driver
WH 12DH
Capacity
Item Cordless Impact Wrench
WR 12DH
Small screw M4 --- M8 (5/32" --- 5/16")*1
Ordinary bolt M5 --- M12 (3/16" --- 15/32") Ordinary bolt M6 --- M14 (1/4" --- 9/16")
High-strength bolt M6 --- M10 (1/4" --- 3/8")
Tightening torque 1,000 kgf•cm (98 N•m, 72 ft-lbs)*2
1,200 kgf•cm (117.6 N•m, 86.4 ft-lbs) *3
Tip condition 6.35 mm (1/4") Bit holder 12.7 mm (1/2") Square drive
Type of motor Fan cooled rare-earth magnet motor
Enclosure Main body: Polyamide resin •••••• Housing
Aluminum alloy die casting •••••• Hammer case
Storage battery: ABS resign (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 --- 2,200/min
Impact rate 0 --- 3,000/min
Main body 1.7 kg (3.7 lbs) (Includes battery)*4
Battery 0.62 kg (1.4 lbs)
Overall length x height 176 mm (6-15/16") x 245 mm (9-21/32")
Center height 26 mm (1-1/64")
Battery (Type EB 12B) Sealed cylindrical nickel-cadmium batteries
Nominal voltage: DC 12V
Nominal life: Charging/discharging approximately 1,000 cycles (in case of Model
UC 14YF or UC 14YF2)
Nominal capacity: 2,000 mAh
180 mm (7-1/8") x 245 mm (9-21/32")
Battery (Type EB 12H) Sealed cylindrical nickel-metal hydride batteries
Nominal voltage: DC 12V
Nominal life: Charging/discharging approximately 500 cycles (in case of Model
UC 14YF2)
Nominal capacity: 2,200 mAh
*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 M12 (15/32") bolt (strength grade: 12.9) for 3 sec. with a hexagonal socket.
*3: This torque is based on tightening an M14 (9/16") bolt (strength grade: 12.9) for 3 sec. with a hexagonal socket.
*4: Main body does not include accessory tools (hexagonal bit, etc.).
Charger
(Model UC 14YF or
UC 14YF2)
Charger power source: single-phase AC, 50/60 Hz
Voltage: Depending on the order specification
Power input: 44 W
Charging system: Constant current charge with full wave phase control
Overcharge protection system: (1) Battery voltage detection ( 2V system)
(2) Battery surface temperature detection
(thermostat or thermistor)
(3) 120 minute timer
Output voltage: 7.2 V --- 14.4 V
Output current: 1.9 A
Charging time: Approx. 60 minutes (for B-type storage battery at 20 C)
Approx. 70 minutes (for H-type storage battery at 20 C)
Product weight: 1.3 kg
Operable ambient temperature range: 0 C --- 40 C
The maximum allowable temperature of the EB12B type battery is 60 C and the
EB 12H type battery is 45 C when recharging with the charger Model UC 14YF2.
Weight

--- 7 ---
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 14YF/UC 14YF2)
Red pilot lamp
remains lit of flashes
Green pilot lamp is lit
Storage battery or charger
is faulty.
Charging not possible
because storage battery
temperature is too high.
6-2. Optional Accessories
(1) Optional accessories for the Model WH 12DH
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")

--- 8 ---
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.
(2) Optional accessories for the Model WR 12DH
Each dimension and applicable bolt for each hexagon socket
Shape B Shape C Shape D
H
D
1
L1L
D
1
L1L
D
1
L1L
Sq
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")
8
(5/16")
8
(5/16")
9
(11/32")
9
(11/32")
8
(5/16")
9
(11/32")
10
(3/8")
14
(9/16")
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")
B
B
B
B
C
C
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")
W 5/16"
W 3/8"
W 7/16"
W 1/2"
M 8
(5/16")
M 10
(3/8")
M 12
(15/32")
M 14
(9/16")
M 16
(5/8")
M 6
(1/4")
M 8
(5/16")
M 10
(3/8")
M 12
(15/32")
M 14
(9/16")
M 12
(15/32")
944291
873632
873539
873540
873536
873624
873626
873627
10 mm
12 mm
13 mm
14 mm
17 mm
19 mm
21 mm
22 mm
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)
ISO
(high-strength)
ISO
(ordinary)
ISO
(small type)
Inch
screw L L1D1
Each dimension and applicable bolt for each long socket
Shape B Shape D
H
D
1
(dia.)
L1
LL1
LSq
L2
D
1
(dia.)
L2

--- 9 ---
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")
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")
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
(2-15/16")
52
(2-3/64")
B
B
B
B
B
B
B
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")
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 8
(5/16")
M 10
(3/8")
M 12
(15/32")
M 12
(15/32")
M 14
(9/16")
M 14
(9/16")
M 16
(5/8")
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 12
(15/32")
955138
955139
955140
955141
955149
955142
955150
955143
955151
991480
955144
12 mm
13 mm
14 mm
17 mm
17 mm
19 mm
19 mm
21 mm
21 mm
21 mm
22 mm
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)
ISO
(high-strength)
ISO
(ordinary)
ISO
(small type)
Inch
screw LL1D1
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")
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")
L2
Part name Overall length
(mm) Code No.
Plus hds.
driver bit
No.2
Plus hds.
driver bit
No.3
45 (1-25/32") 955229
70 (2-3/4") 955654
45 (1-25/32") 955230
70 (2-3/4") 955655
Extension bar [Overall length 100 mm (3-15/16") ] (Code No. 873633)
Universal joint (Code No. 992610)
Socket ass'y for duct •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• Hexagonal two side width of
applicable bolts Code No.
993658
13 (1/2") 992613
14 (9/16") 992615
12 (15/32")
EW-14R corner attachment (Code No. 9329-9001)

--- 10 ---
(3) Optional accessories for the Models WH 12DH and WR 12DH
Holster (Code No. 307824)
Use the holster to hold the unit during its operation.
Carefully read the warnings attached to the holster for safe use.
Hook (Code No. 308090)
Use the hook to hold the unit during its operation.
Carefully read the instructions that come with the hook to learn how to use it.

--- 11 ---
7. COMPARISONS WITH SIMILAR PRODUCTS
7-1. Specification Comparisons (Cordless Impact Driver)
M 4 --- M 8
(5/32" --- 5/16")
HITACHI
WH 12DH WH 12DC C
Maker
Model
Item M 4 --- M 8
(5/32" --- 5/16") M 4 --- M 8
(5/32" --- 5/16")
*1
Catalog specifications
Capacity
Small screw
M 5 --- M 12
(3/16" --- 15/32") M 5 --- M 12 (3/16" --- 15/32") M 5 --- M 12 (3/16" --- 15/32")
Ordinary bolt
M 5 --- M 10
(3/16" --- 3/8") M 5 --- M 10 (3/16" --- 3/8") M 5 --- M 10 (3/16" --- 3/8")
High-strength bolt
1,000
(98 N•m, 72 ft-lbs) 900 (88.2 N•m, 65 ft-lbs) 1,000 (98 N•m, 72 ft-lbs)
Max. tightening torque kgf•cm
0 --- 2,200 [1,700] 0 --- 2,000 0 --- 2,200No-load rotation speed /min
0 --- 3,000 [2,700] 0 --- 2,900 0 --- 3,000Impact rate /min 1.7 (3.7 lbs)
[1.6 (3.5 lbs)] 1.7 (3.7 lbs) 1.7 (3.7 lbs)Main body weight kg
1,070 (104.9 N•m, 77 ft-lbs)
[860 (84.3 N•m, 62 ft-lbs)]
930
(91 N•m, 67 ft-lbs) 1,000 (98 N•m, 72 ft-lbs)
Max. tightening torque
kgf•cm
Measured figures
0 --- 2,180 [1,680] 0 --- 2,010 0 --- 2,160No-load rotation speed /min 0 --- 2,900 [2,700] 0 --- 2,900 0 --- 2,860Impact rate /min
176 x 245 [221] (6-15/16"x
9-21/32" [8-45/64"]) 198 x 245
(7-25/32" x 9-21/32")
Overall length x height mm 176 x 232
(6-15/16" x 9-1/8")
26 (1-1/64") 26 (1-1/64") 26 (1-1/64")Center height mm 1.73 (3.8 lbs) 1.73 (3.8 lbs) 1.73 (3.8 lbs)Main body weight kg
69 69 69
No-load sound pressure level
dB(A) Driver chuck Driver chuck Driver chuck
Tool tip mounting system
Variable speed switch with
forward/reverse
changeover lever
Type of switch Variable speed switch with
forward/reverse
changeover lever
Variable speed switch with
forward/reverse
changeover lever
DC magnet DC magnet DC magnet
Type of motor
12 [9.6] 12 12
Voltage
17 [13] 17 17
Current
EB 12B, EB 12H EB 12 1222
Battery
V
A
Type EB 12B: 2,000
EB 12H: 2,200 [1,200] 1,200 2,000
Nominal capacity mAh
12 [9.6] 12 12
Nominal voltage V
0 --- 40 5 --- 40 ------
Ambient temperature
CUC 14YF or UC 14YF2 UC 12Y DC1411
Model
44 51 ------
Power input capacity
VA
7.2 --- 14.4 2.4 --- 12 7.2 --- 14.4
Recharging voltage
VPlastic tool case
Charger (UC 14YF or
UC 14YF2)
Plastic tool case
Charger (UC 12Y) Plastic tool case Charger (DC1411)
Standard accessories
Charger
[ ]: in the case of EB9 type battery
*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 M12 (5/32") bolt (strength grade: 12.9) for 3 sec. with a hexagon socket.
*3: Main body weight does not include accessory tools (hexagon bit, etc.).
*1
*2
*3
*2
*3

--- 12 ---
7-2. Specification Comparisons (Cordless Impact Wrench)
HITACHI
WR 12DH WH 12D C
Maker
Model
Item
Catalog specifications
Capacity
M 6 --- M 14
(1/4" --- 9/16") M 6 --- M 14 (1/4" --- 9/16") M 8 --- M 14 (5/16" --- 9/16")
Ordinary bolt
M 6 --- M 10
(1/4" --- 3/8") M 6 --- M 12
(1/4" --- 15/32") M 6 --- M 12 (1/4" --- 15/32")
High-strength bolt
1,200
(117.6 N•m, 86.4 ft-lbs) 1,200
(117.6 N•m, 86.4 ft-lbs) 1,200 (117.6 N•m, 86.4 ft-lbs)
Max. tightening torque
kgf•cm
0 --- 2,200 0 --- 1,500 0 --- 1,800No-load rotation speed /min 0 --- 3,000 0 --- 2,300 0 --- 2,500Impact rate /min
1.7 (3.7 lbs) 2.3 (5.1 lbs) 1.8 (3.9 lbs)
Main body weight kg
1,300
(127.4 N•m, 93.6 ft-lbs) 1,200
(117.6 N•m, 86.4 ft-lbs) 1,270
(124.5 N•m, 91.4 ft-lbs)
Max. tightening torque
kgf•cm
Measured figures
0 --- 2,180 0 --- 1,550 0 --- 1,990No-load rotation speed /min
0 --- 2,900 0 --- 2,300 0 --- 2,500Impact rate /min 180 x 245
(7-1/8" x 9-21/32") 230 x 253 (9" x 10")
Overall length x height mm 221 x 230
(8-3/4" x 9-1/8")
26 (1-1/64") 33.5 (1-5/16") 33 (1-5/16")Center height mm
1.73 (3.8 lbs) 2.3 (5.1 lbs) 1.94 (4.3 lbs)Main body weight kg
69 65 72
No-load sound pressure level
dB(A) Pin/O-ring or plunger Pin/O-ring or plunger ------
Tool tip mounting system
Variable speed switch with
forward/reverse
changeover lever
Type of switch Variable speed switch with
forward/reverse
changeover lever
Variable speed switch with
forward/reverse
changeover lever
DC magnet DC magnet DC magnet
Type of motor
12 12 12
Voltage
17 16 17
Current
EB 12B, EB 12H EB 12B 1222
Battery
V
A
Type EB 12B: 2,000
EB 12H: 2,200 2,000 2,000
Nominal capacity mAh
12 12 12
Nominal voltage V
5 --- 40 5 --- 40 ------
Ambient temperature
CUC 14YF or UC 14YF2 UC 12Y DC1201
Model
44 51 ------
Power input capacity
VA
7.2 --- 14.4 2.4 --- 12 2.4 --- 12
Recharging voltage
VPlastic tool case
Charger (UC 14YF or
UC 14YF2)
Plastic tool case
Charger (UC 12Y) Plastic tool case Charger (DC1201)
Standard accessories
Charger
*1: Max. tightening torque is based on tightening an M14 (9/16") bolt (strength grade: 12.9) for 3 sec. with a hexagon socket.
*2: Main body weight does not include accessory tools (hexagon bit, etc.).
*1
*2
*1
*2

--- 13 ---
7-3. Tightening torque
7-3-1. Tightening Torque Characteristic comparisons
The Model WH 12DH and WR 12DH provide greater tightening torque than that of the previous models thanks to
the high power rare-earth magnet motor and the higher moment of inertia of the hammer. The tightening torque
does not drop even when loosening bolts because the motor runs at the same torque and speed in both the
forward and reverse directions.
Tightening torque comparisons of Models WH 12DH and WR 12DH with previous models are shown in Figs. 4-1
and 4-2. It should be noted that M12 (15/32") and M14 (9/16") strength grade 12.9 high-strength bolts were
utilized in the tests to ensure that the bolts were not stripped or distorted, even though such bolts are actually
beyond the recommended maximum capacity of these models. Accordingly, the data in the figures below are
intended for reference purposes only.
Fig. 4-1 Fig. 4-2
Test conditions
Bolt: M12 x 45 mm (15/32" x 1-25/32")
(strength grade: 12.9)
Steel plate: Mild steel, thickness: 25 mm (1")
Accessory tool: Hexagon socket
Bolt: M14 x 50 mm (9/16" x 2")
(strength grade: 12.9)
Steel plate: Mild steel, thickness: 25 mm (1")
Accessory tool: Hexagon socket
HITACHI
WH 12DH
HITACHI
WH 12DC
200
(19.6 N
•
m,
14 ft-lbs)
0 123
400
(39.2 N
•
m,
29 ft-lbs)
600
(58.8 N
•
m,
43 ft-lbs)
800
(78.4 N
•
m,
58 ft-lbs)
1000
(98 N
•
m,
72 ft-lbs)
1200
(117.6 N
•
m,
86 ft-lbs)
1400
(137.2 N
•
m,
100 ft-lbs)
(kgf
•
cm)
(sec)
Tightening time
Tightening torque
HITACHI
WH 12DH
C
200
(19.6 N
•
m,
14 ft-lbs)
0 123
400
(39.2 N
•
m,
29 ft-lbs)
600
(58.8 N
•
m,
43 ft-lbs)
800
(78.4 N
•
m,
58 ft-lbs)
1000
(98 N
•
m,
72 ft-lbs)
1200
(117.6 N
•
m,
86 ft-lbs)
1400
(137.2 N
•
m,
100 ft-lbs)
(kgf
•
cm)
(sec)
Tightening time
Impact Driver Impact Wrench
Tightening torque
HITACHI
WH 12D
C (forward)
[Tightening torque
in reverse rotation
is about 87% of
that in forward
rotation.]

--- 14 ---
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
Fig. 5
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
05
(3/16") 6 (1/4") 8 (5/16") 10 (3/8") 12 (15/32") 14 (9/16")mm
200
(19.6 N
•
m, 14 ft-lbs)
400
(39.2 N
•
m, 29 ft-lbs)
600
(58.8 N
•
m, 43 ft-lbs)
800
(78.4 N
•
m, 58 ft-lbs)
1000
(98 N
•
m, 72 ft-lbs)
1200
(117.6 N
•
m, 86 ft-lbs)
(kgf
•
cm)
Thread diameter
Appropriate tightening torque
Table 1
Table 2

--- 15 ---
7-3-3. Bolt Tightening Torque Characteristics
Figs. 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.
Model WH 12DH
Fig. 6-1
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)
Ordinary bolt
High-strength bolt
5/16" x 1-3/6"
(M8 x 30 mm)
Tightening time: sec
[steel plate thickness:
t = 3/8" (10 mm)]
200
(19.6 N
•
m, 14 ft-lbs)
400
(39.2 N
•
m, 29 ft-lbs)
600
(58.8 N
•
m, 43 ft-lbs)
800
(78.4 N
•
m, 58 ft-lbs)
1000
(98 N
•
m, 72 ft-lbs)
(kgf
•
cm)
Tightening torque
0123
Ordinary bolt
High-strength bolt
15/32" x 1-3/4"
(M 12 x 45 mm)
Tightening time: sec
[steel plate thickness:
t = 1" (25 mm)]
200
(19.6 N
•
m, 14 ft-lbs)
400
(39.2 N
•
m, 29 ft-lbs)
600
(58.8 N
•
m, 43 ft-lbs)
800
(78.4 N
•
m, 58 ft-lbs)
1000
(98 N
•
m, 72 ft-lbs)
1200
(117.6 N
•
m, 86 ft-lbs)
(kgf
•
cm)
Tightening torque
00123
Ordinary bolt
High-strength bolt
8/8" x 1-3/6"
(M 10 x 30 mm)
Tightening time: sec
[steel plate thickness:
t = 3/8" (10 mm)]
200
(19.6 N
•
m, 14 ft-lbs)
400
(39.2 N
•
m, 29 ft-lbs)
600
(58.8 N
•
m, 43 ft-lbs)
800
(78.4 N
•
m, 58 ft-lbs)
1000
(98 N
•
m, 72 ft-lbs)
(kgf
•
cm)
Tightening torque
00123

--- 16 ---
Model WR 12DH
Fig. 6-2
Ordinary bolt
High-strength bolt
5/16" x 1-3/6"
(M8 x 30 mm)
Tightening time: sec
[steel plate thickness:
t = 3/8" (10 mm)]
200
(19.6 N
•
m, 14 ft-lbs)
400
(39.2 N
•
m, 29 ft-lbs)
600
(58.8 N
•
m, 43 ft-lbs)
800
(78.4 N
•
m, 58 ft-lbs)
1000
(98 N
•
m, 72 ft-lbs)
(kgf
•
cm)
Tightening torque
00123
Ordinary bolt
High-strength bolt
15/32" x 1-3/4"
(M12 x 45 mm)
Tightening time: sec
[steel plate thickness:
t = 1" (25 mm)]
200
(19.6 N
•
m, 14 ft-lbs)
400
(39.2 N
•
m, 29 ft-lbs)
600
(58.8 N
•
m, 43 ft-lbs)
800
(78.4 N
•
m, 58 ft-lbs)
1000
(98 N
•
m, 72 ft-lbs)
1200
(117.6 N
•
m, 86 ft-lbs)
(kgf
•
cm)
Tightening torque
00123
Ordinary bolt
High-strength bolt
8/8" x 1-3/6"
(M10 x 30 mm)
Tightening time: sec
[steel plate thickness:
t = 3/8" (10 mm)]
200
(19.6 N
•
m, 14 ft-lbs)
400
(39.2 N
•
m, 29 ft-lbs)
600
(58.8 N
•
m, 43 ft-lbs)
800
(78.4 N
•
m, 58 ft-lbs)
1000
(98 N
•
m, 72 ft-lbs)
(kgf
•
cm)
Tightening torque
00123

--- 17 ---
7-4. Number of Screws or Bolts Driven
7-4-1. Per-Charge Working Capacity Comparisons
Test data on the number of screws or bolts which can be driven per battery charge by the new models vs. the
previous models are shown in the tables below. Please note that the data below are intended for general
reference only as the number of screws which can be tightened per charge will vary slightly depending on screw
tightening conditions, screw sizes, ambient temperatures and the charging capacity of the battery.
(1) Number of screws or bolts driven (Cordless impact driver)
Battery
Tightening condition Model HITACHI
WH 12DH HITACHI WH 12DC C
EB 12B EB 12B 1222
(Corresponding EB 12B)
Wood screw 3.8 mm dia. x 20 mm
(soft wood) 820 800 820
Wood screw 4.5 mm dia. x 50 mm
(soft wood) 450 450 450
Wood screw 4.2 mm dia. x 75 mm
(soft wood) 270 270 270
Machine screw
(M8 x 16 mm) 1,400 1,400 1,400
Machine screw
(M8 x 25 mm) 1,230 1,230 1,230
Tex screw 4.0 mm dia. x 13 mm
SPCC t=1.6 210 210 210
(2) Ordinary bolt (Cordless impact wrench)
Battery
Tightening condition Model HITACHI
WH 12DH HITACHI WH 12D C
EB 12B EB 12B 1222
(Corresponding EB 12B)
M8
ordinary bolt 1,960
0.2 2,240 0.2 1,880
0.2
Number of bolts
Time (sec)
M10
ordinary bolt 780
0.5 900 0.5 750
0.5
Number of bolts
Time (sec)
M12
ordinary bolt 490
0.8 660 0.8 470
0.8
Number of bolts
Time (sec)