Hitachi WH 8DH, WR 8DH Technical Data And Service Manual

POWER TOOLS

TECHNICAL DATA

AND

SERVICE MANUAL

CORDLESS IMPACT DRIVER

WH 8DH

CORDLESS IMPACT WRENCH

WR 8DH

SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT

LIST Nos. WH 8DH: F832
WR 8DH: F833

Jul. 1999

W

MODEL

WH 8DH

WH 8DH

WR 8DH

WR 8DH

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

6908DWA

WH 8DH

Page

CONTENTS

[ Business Section ]

1. PRODUCT NAME

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1

2. MARKETING OBJECTIVE

•••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••

1

3. APPLICA TIONS

•••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••

1

4. SELLING POINTS

••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••

2

4-1. Selling Point Descriptions

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5. SPECIFICATIONS

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5

5-1. Specifications

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5

5-2. Optional Accessories

••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••

6

6. COMPARISONS WITH SIMILAR PRODUCTS

•••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••

10

6-1. Specification Comparisons (Cordless Impact Driver)

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6-2. Specification Comparisons (Cordless Impact Wrench)

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11

6-3. Tightening Torque

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12

6-4 Tightening Speed

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16

6-5. Number of Screws or Bolts Driven

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7. PRECAUTIONS IN SALES PROMOTION

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7-1. Safety Instructions

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7-2. Tightening Torque Inspection Prior to Operation

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7-3. Tightening Torque V ariation

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7-4. Suggestions and precautions for the Efficient Use of the Charger

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23

8. OTHER PRECAUTIONS

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[ Service section ]

9. REPAIR GUIDE

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9-1. Precautions in Disassembly and Reassembly

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9-2. Precautions in Disassembly and Reassembly of Battery Charger

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11. STANDARD REPAIR TIME (UNIT) SCHEDULES

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[ Appendix ]

Assembly Diagram for WH 8DH

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Assembly Diagram for WR 8DH

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--- 1 ---

1. PRODUCT NAME

Hitachi Cordless Impact Driver, Model WH 8DH
Hitachi Cordless Impact Wrench, Model WR 8DH

2. MARKETING OBJECTIVE

The current Hitachi cordless impact driver series has provided excellent on-the-job performance thanks to their
design that produces no recoil force in tightening screws and bolts and also no damage to the screw heads.
The current DC 12V cordless impact driver Model WH 12DH and the cordless impact wrench Model WR 12DH
are well-reputed because they have better tightening performance and longer service life than previous models,
thanks to a replaceable carbon brush motor. Now, the new cordless impact driver Model WH 8DH is brought out
to respond to users' requests for a replaceable carbon brush motor for a DC 9.6 V product. The new cordless
impact wrench Model WR 8DH is also brought out. The Model WR 8DH has higher tightening torque than the
previous Model WH 8D2 and its square drive dimension is 12.7 mm (1/2") for use of commercially-available 1/2"
sockets. The construction of the Model WR 8DH is the same as that of the Model WH 8DH except the anvil (K)
assembly and the hammer case.

3. APPLICA TIONS

•

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, lag bolts, etc.

•

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 signs, automobile repair, assembly of garages

and carports storage sheds, etc.

•

Various other assembly, construction or repair facilities.

--- 2 ---

4. SELLING POINTS

(1) Cordless Impact Driver: WH 8DH

Faster screw fastening

Higher fastening torque

88.2 N•m (900 kgf•cm, 65 ft-lbs)

Improved motor performance

•

Replaceable carbon brushes for longer

motor life

•

High-power fan-cooled DC magnet motor

•

Higher heat-resistance

•

The same torque and speed in both

forward and reverse modes

Longer service life

DC 9.6 V battery
EB 9B or EB 9H

Heavy-duty aluminum
hammer case

Variable speed switch
with electric brake

Easy-to-use forward/reverse
changeover pushing button

Ergonomically designed
handle for a comfortable grip

Grip inserts
front and rear

--- 3 ---

(2) Cordless Impact Wrench: WR 8DH

Higher fastening torque

98 N•m (1000 kgf•cm, 72 ft-lbs)

Improved motor performance

•

Replaceable carbon brushes for longer

motor life

•

High-power fan-cooled DC magnet motor

•

Higher heat-resistance

•

The same torque and speed in both

forward and reverse modes

Longer service life

DC 9.6 V battery
EB 9B or EB 9H

Heavy-duty aluminum
hammer case

Variable speed switch
with electric brake

Easy-to-use forward/reverse
changeover pushing button

Ergonomically designed
handle for a comfortable grip

[12.7 mm (1/2") Square drive]

Grip inserts
front and rear

--- 4 ---

4-1. Selling Point Descriptions

(1) Faster tightening speed

The Model WH 8DH provides faster driving speed than the previous model thanks to the high-power motor
and the higher moment of inertia of the hammer.
Tightening time comparison of the Model WH 8DH with the previous Model WH 8DA2 and maker C's model
are shown below. (Wood screw 4.2 mm dia. x 90 mm length, hemlock spruce)

HITACHI WH 8DH
HITACHI WH 8DA2

C

5.9 sec.

Model

510

sec.

6.5 sec.

6.8 sec.

(2) Improved motor performance

The Models WH 8DH and WR 8DH have high power thanks to the fan cooled DC magnet motor. They 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 size by about 70
% (volume) compared to our previous model.

(3) 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 on the outside of the brush tube.

Claw of
carbon brush

Collar of
carbon brush

Connecting portion at the
outside of brush tube

Fig. 1 Fig. 2 Fig. 3

(4) Safe handle shape

Compared with the previous WH 8DA2, the housing of the Model WH 8DH produces no clearance caused by
vibration because front and rear grip inserts [part names: grip (R) and grip (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 so not
to interfere with the base of the operator's thumb.

--- 5 ---

5. SPECIFICATIONS

5-1. Specifications

Model

Cordless Impact Driver

WH 8DH

Capacity

Item

Cordless Impact Wrench

WR 8DH

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

88.2 N•m (900 kgf•cm, 65 ft-lbs)*

2

98 N•m (1000 kgf•cm, 72 ft-lbs)

*

3

Tip condition

6.35 mm (1/4") Bit holder

12.7 mm (1/2") Square drive

Type of motor

Fan cooled DC 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 and variable)

Handle configuration

T-type

No-load rotational speed

0 --- 2,200 /min

Impact rate

0 --- 2,900 /min

Main body

1.6 kg (3.5 lbs) (Includes battery)*

4

Battery

0.52 kg (1.1 lbs)

Overall length x height

176 mm (6-15/16") x 220 mm (8-21/32")

Center height

26 mm (1-1/64")

Battery (Type EB 9B)

Sealed cylindrical nickel-cadmium batteries
Nominal voltage: DC 9.6V
Nominal life: Charging/discharging approximately 1,000 cycles (in case of Model
UC 14YF2)
Nominal capacity: 2.0 Ah

180 mm (7-1/8") x 220 mm (8-21/32")

Battery (Type EB 9H)

Sealed cylindrical nickel-metal hydride batteries
Nominal voltage: DC 9.6V
Nominal life: Charging/discharging approximately 500 cycles (in case of Model
UC 14YF2)
Nominal capacity: 2.2 Ah

*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 seconds with a hexagonal socket.

*

3

: This torque is based on tightening an M12 (15/32") bolt (strength grade: 12.9) for 3 seconds with a hexagonal socket.

*

4

: Main body does not include accessory tools (hexagonal bit, etc.).

Charger (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 EB 9B type battery is 60 ˚C and the
EB 9H type battery is 45 ˚C.

Weight

--- 6 ---

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 (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.

5-2. Optional Accessories

(1) Optional accessories for the Model WH 8DH

•

Plus driver bit

50 mm (2")

Bit No.

No. 2
No. 3

Code No.

992671
992672

•

Hexagon socket

L

B

Stamped figures

996177 8 (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")

--- 7 ---

•

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 8DH

•

Each dimension and applicable bolt for each hexagon socket

Shape B

Shape C Shape D

H

D

1

L1

L

D

1

L1

L

D

1

L1

L

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

L

1 D1

•

Each dimension and applicable bolt for each long socket

Shape B Shape D

H

D

1

(dia.)

L1

L

L1

L

Sq

L

2

D

1

(dia.)

L2

--- 8 ---

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

L

L

1

D1

•

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 hd.

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

••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••

Dihedral 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)

--- 9 ---

(3) Optional accessories for the Models WH 8DH and WR 8DH

•

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.

--- 10 ---

6. COMPARISONS WITH SIMILAR PRODUCTS

6-1. Specification Comparisons (Cordless Impact Driver)

M 4 --- M 8

(5/32" --- 5/16")

HITACHI

WH 8DH WH 8DA2

C

Maker
Model

Item

M 5 --- M 8

(3/16" --- 5/16")

M 4 --- M 8

(5/32" --- 5/16")

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

88.2

(900 kgf•cm, 65 ft-lbs)*

2

78.4

(800 kgf•cm, 58 ft-lbs)*

3

78.4

(800 kgf•cm, 58 ft-lbs)*

3

Max. tightening torque N•m

0 --- 2,200

2,200 0 --- 2,200No-load rotation speed

/min

0 --- 2,900

2,800 0 --- 2,800Impact rate

/min

1.6 (3.5 lbs) 1.4 (3.1 lbs) 1.4 (3.1 lbs)Main body weight

kg

91.1

(930 kgf•cm, 67.3 ft-lbs)*

2

83.8

(850 kgf•cm, 61 ft-lbs)*

3

85.8

(875 kgf•cm, 63.3 ft-lbs)*

3

Max. tightening torque

N•m

Measured figures

0 --- 2,230

2,150 0 --- 2,470No-load rotation speed

/min

0 --- 2,790

2,700 0 --- 2,680Impact rate

/min

176 x 220

(6-15/16" x 8-21/32")

175 x 218

(6-7/8" x 8-19/32")

Overall length x height

mm

171 x 232

(6-47/64" x 9-9/64")

26 (1-1/64")

26 (1-1/64") 26 (1-1/64")Center height

mm

1.6 (3.5 lbs)

1.47 (3.2 lbs) 1.5 (3.3 lbs)Main body weight

kg

67

66 68

No-load sound pressure level

dB(A)

Driver chuck

Driver chuck Driver chuck

Tool tip mounting system

Trigger switch with
forward / reverse
changeover pushing
button with brake and
variable

Type of switch

Trigger switch with
forward / reverse
changeover pushing
button with brake

Variable speed switch with
forward/reverse
changeover lever

DC magnet

DC magnet DC magnet

Type of motor

9.6

9.6 9.6

Voltage

20

20 20

Current

EB 9B or EB 9H

EB 9 9122

Battery

V
A

Type

EB 9B: 2.0
EB 9H: 2.2

1.3 2.0

Nominal capacity

Ah

9.6

9.6 9.6

Nominal voltage

V

0 --- 40

5 --- 40 ------

Ambient temperature

˚C

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

V

•

Plastic tool case

•

Charger (UC 14YF2)

•

Plastic tool case

•

Charger (UC 12Y)

•

Plastic tool case

•

Charger (DC1411)

Standard accessories

Charger

*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 seconds with a hexagon

socket.
*3: Max. tightening torque is based on tightening an M10 (3/8") bolt (strength grade: 12.9) for 3 seconds with a hexagon socket.
*

4

: Main body weight does not include accessory tools (hexagon bit, etc.).

*

1

*

4

*

2

*

4