Hitachi Koki WH 18DD User manual

PRODUCT NAME
18 V Cordless Impact Driver
Models WH 18DD, WH 18DDX
WH 18DDX: For the UK
WH 18DD: For other regions
REPAIR GUIDE ---------------------------------------------------------------------------------------------------------------- 1
1. Precautions on disassembly and reassembly ----------------------------------------------------------- 1
• Disassembly ---------------------------------------------------------------------------------------------------- 1
• Reassembly ---------------------------------------------------------------------------------------------------- 4
• Type of silicone rubber --------------------------------------------------------------------------------------- 8
• Lubrication points and type of lubricant ------------------------------------------------------------------ 8
• Tightening torque ---------------------------------------------------------------------------------------------- 9
• Checking after reassembly --------------------------------------------------------------------------------- 9
• No-load current ------------------------------------------------------------------------------------------------ 9
• Wiring diagram ----------------------------------------------------------------------------------------------- 10
2. Precautions on disassembly and reassembly of the charger -------------------------------------- 10
CONTENTS Page
W
Power Tools Service Manual
CONFIDENTIAL
Jul. 2020
Overseas Sales Management Dept.
WH 18DD

-1-
• Removal of the guide sleeve
WARNING: Always remove the battery from the main body before starting repair or maintenance
work. Because the tool is cordless, inadvertently activating the switch with the battery
left in the main body will start the motor rotating unexpectedly, and could cause
serious injury.
1. Precautions on disassembly and reassembly
[Bold] numbers in the description below correspond to the item numbers in the parts lists and exploded
assembly diagrams for the Models WH 18DD and WH 18DDX.
1. Removal of the guide sleeve
Remove the Retaining Ring [2], Washer (D) [3], Guide Spring (D) [4], and Guide Sleeve (D) [5] in this
order with a small flat-blade screwdriver. Do not work too quickly. Be careful not to let the Retaining Ring
[2] pop up, and do not lose the two Steel Balls D3.5 [9] in the opening of the Anvil [10].
Disassembly
REPAIR GUIDE
Opening of the
Retaining Ring [2]
[2]
Insert the edge of a small flat-blade screwdriver
under the end of the Retaining Ring [2].
Secure the body and align the opening of the
Retaining Ring [2] with the notch on the Anvil [10].
Slowly raise the Retaining
Ring [2] from the end to
remove it from the Anvil [10].
Hold Washer (D) [3] and Guide Spring (D)
[4] with fingers to prevent them from popping
up together with the Retaining Ring [2].
[10]
[3]
[2]
[5]
[2]
[5]
[2]
[3]
[4]
[10]
Notch on the Anvil [10]

-2-
• Disassembly of the hammer assembly
J-297 base for washer (S)
(special-purpose tool)
Highest point of the cam
groove in the Spindle [18]
Steel ball insertion groove
[18]
[15]
[17]
[16]
[12]
[18]
[11]
2. Removal of the exterior parts
Insert the edge of a small flat-blade screwdriver into the space between the Front Cap [6] and the Hammer
Case [7], and remove the Front Cap [6] from the Hammer Case [7].
3. Removal of housing (A).(B) set
(1) Remove the nine Tapping Screws (W/Flange) D3 x 16 [27] to remove housing (B) of Housing (A).(B)
Set [33].
(2) Remove the Hammer Case [7], hammer assembly, Inner Cover [26], and Wiring Ass’y [29] together as
one unit. Remove the Pushing Button [30].
4. Disassembly of the hammer assembly
(1) Set the hammer assembly detached from the Hammer Case [7] on the J-297 base for washer (S)
(special-purpose tool, Code No. 317063). Push down the end of the Spindle [18] with a hand press or
similar tool to compress the Hammer Spring [15], and then use a small flat-blade screwdriver or similar
tool to take out Stopper (A) [17] in this state. Release the hand press.
(2) Remove the hammer assembly from the J-297 base for washer (S). Hold the end surface of the
Spindle [18]. Then push down either of the tabs on the Hammer [12] with a hand press or similar tool
to compress the Hammer Spring [15]. In this state, use a small flat-blade screwdriver or similar tool to
remove the two Steel Balls D5.556 [11] from the cam groove in the Spindle [18] and Hammer [12].
(3) Release the hand press, hold the Hammer [12] and Washer (S) [16] together, and then pull both out
from the Spindle [18]. You can now take out the Hammer Spring [15].
Press down.
Tab on the Hammer [12]

-3-
5. Removal of the inner cover
Detach Ring Gear (A) [23] and O-ring [24] from the Inner Cover [26], and then use a small flat-blade
screwdriver to remove Damper (A) [25].
NOTE: Be careful not to damage the O-ring [24].
• Removal of the inner cover
[23]
[24]
[21]
[25]
[26]
[22]

-4-
• Reassembly of the power supply unit and its vicinity
Generally, perform reassembly by reversing the disassembly procedure. However, special attention should
be given to the following items.
1. Reassembly of the power supply unit and its vicinity
Reassembly
[30]
Fit the protrusion of the direction
selector lever of the switch into the
hole of the Pushing Button [30].
Insert the brown internal wire into the
internal wire threading groove first, then
insert the orange internal wire, blue
internal wire, and purple internal wire
into the internal wire threading groove.
Insert the tip (connector) of the D wire
(blue) into the space in the housing.
NOTE: The D wire is intended for
exterior communication so
that the supplier can check
the controller status.
LED

-5-
2. Mounting the mechanical parts
(1) Mount Washer (S) [16] to the Spindle [18]. Put the twenty-eight Steel Balls D3.175 [13], Washer (J)
[14], and Hammer Spring [15] in the Hammer [12], and mount it to the Spindle [18].
(2) Align the highest point of the cam groove in the Spindle [18] with the steel ball insertion groove in the
Hammer [12]. Push down the tabs on the Hammer [12] with a hand press or similar tool to compress
the Hammer Spring [15] until it contacts the Spindle [18] and hold it there.
(3) Insert the two Steel Balls D5.556 [11] into the steel ball insertion groove. Check that the two Steel Balls
D5.556 [11] are in the groove, and then loosen the hand press.
(4) Set the hammer assembly onto the J-297 base for washer (S) (special-purpose tool, Code No.
317063), press the hand press down on the edge of the Spindle [18] to compress the Hammer Spring
[15], and then mount Stopper (A) [17] to the Spindle [18]. Loosen the hand press to complete the
procedure.
(5) Mount the Idle Gear Set (2 pcs.) [19] and two Needle Rollers (A) [20] to the Spindle [18] and insert
Washer (E) [21] to assemble the hammer assembly.
(6) Press-fit the Ball Bearing 6901VV [22] into the Inner Cover [26] and fit two Dampers (A) [25] into the
Inner Cover [26]. Then fit the O-ring [24] into Ring Gear (A) [23], and fit the retaining rib of Ring Gear
(A) [23] into the concave portion of Damper (A) [25].
(7) Check the hammer assembly (whether Washer (E) [21] is inserted into the Spindle [18]) for proper
engagement of the Idle Gear Set [19] with Ring Gear (A) [23], and mount it to the Inner Cover [26].
(8) Insert the Anvil [10] into the tip of the Spindle [18] of the hammer assembly, and then cover it with the
Hammer Case [7].
NOTE: At that time, make sure that the ribs of the Inner Cover [26] are positioned at 90° relative
to the retaining tabs of the Hammer Case [7].
(9) Press-fit the Wiring Ass’y [29] all the way into the Inner Cover [26]. Make sure that the Wiring Ass’y
[29] turns smoothly. If the Wiring Ass’y [29] does not turn smoothly, its gears could be improperly
engaged. In such a case, mount the Wiring Ass’y [29] properly.
90°
Retaining tabs of the Hammer Case [7]
• Mounting the mechanical parts
Ribs of the Inner Cover [26]

-6-
A
pply silicone rubber (Three Bond TB1211) to the shaded areas.
• Application of silicone rubber
3. Reassembly of housing (A).(B) set
(1) Before mounting the parts to housing (A), apply silicone rubber (Three Bond TB1211) to the specified
locations shown in the figure below.
(2) Integrate the hammer assembly, Hammer Case [7], Inner Cover [26], Wiring Ass’y [29] (including the
DC-speed control switch and controller), and Battery Terminal [32] as one unit, and then mount the unit
to housing (A).
NOTE: • Fit the Hammer Case [7] into the housing so that the retaining tab of the Hammer Case
[7] is in contact with the retainer receptor of the housing as shown in the figure below.
• Check whether the Hammer Case [7] is properly inserted into the housing. If the
Hammer Case [7] does not fit into the specified groove of the housing, or if the ribs of
the Inner Cover [26] are not positioned at 90° relative to the retaining tabs of the
Hammer Case [7], reassemble it. The Models WH 18DD and WH 18DDX are structured
so that the Hammer Case [7] will retain the parts axially when properly assembled.
Therefore, make sure that the parts are properly mounted to the housing.
(3) Also coat housing (B) with silicone rubber (Three Bond TB1211) at the similar location. Mount housing
(B) and fasten the nine Tapping Screws (W/Flange) D3 x 16 [27].
NOTE: Use a cloth to wipe off any silicone rubber adhering to the outer circumference of the
housing.

-7-
Make sure the Hammer Case [7]
is securely fitted to housing (A).
Retaining tabs
• Mounting the hammer case
Make the retaining tabs of the Hammer Case [7]
touch housing (A) here.

-8-
• Mounting the guide sleeve
4. Mounting the exterior parts
Mount the Front Cap [6] to the Hammer Case [7].
5. Mounting the guide sleeve
Put the two Steel Balls D3.5 [9] into the Anvil [10]. Mount
Guide Sleeve (D) [5], Guide Spring (D) [4], and Washer (D)
[3] in this order. Use the J-295 jigs (A) and (B) for retaining
ring (special-purpose tools, Code No. 317060 and 317061) to
mount the Retaining Ring [2] in the groove of the Anvil [10].
NOTE: The Retaining Ring [2] may be deformed in the
disassembly procedure and Guide Sleeve (D) [5]
may come off if the deformed Retaining Ring [2]
is reused. Be sure to replace the Retaining Ring
[2] with a new one.
Please purchase the following silicone rubber as necessary.
Item Registered part name Net weight Code No.
Three Bond 1211 Silicone rubber 100 g 306927
Apply specified amount of grease to the following portions.
MOLUB-ALLOY 777-1
• Convex portion (8 mm in dia.) on the Anvil [10]
• Sliding portion between the Anvil [10] and the needle bearing
• Two Steel Balls D5.556 [11]
• Cam groove, oiled groove, and tabs on the Hammer [12]
• Cam groove and sliding portion of the Spindle [18]
• Hole (5 mm in dia.) in the Idle Gear Set (2 pcs.) [19]
• Entire circumference of Needle Roller (A) [20]
• Twenty-eight Steel Balls D3.175 [13]
• Top surface of the tabs on the Anvil [10] and sliding portion of Washer (F) [8]
• Inner circumference of the needle bearing of the Hammer Case [7]
Lubrication points and type of lubricant
Press down here.
[2]
[3]
J-295 jig (B) for retaining ring
(special-purpose tool)
J-295 jig (A) for retaining ring
(special-purpose tool)
Type of silicone rubber

-9-
NIPPECO SEP-3A
• Two Steel Balls D3.5 [9]
• Sliding portion of the Anvil [10] and Guide Sleeve (D) [5]
• Press-fitting portion (rotor side) of the Inner Cover [26]
ATTOLUB MS NO. 2
• Toothed surfaces of the Wiring Ass’y [29] pinions, toothed surface of Ring Gear (A) [23], and
toothed part of the Idle Gear Set [19].
Please purchase the following grease as necessary.
Item Registered part name Net weight Code No.
MOLUB-ALLOY 777-1 Grease (Molub-Alloy No. 777-1) 75 g 75 g 325149
NIPPECO SEP-3A
Grease (SEP-3A) (100 g) 100 g 930035
Grease (SEP-3A) (2.5 kg) 2.5 kg 930038
ATTOLUB MS NO. 2 Grease (Attolub MS No. 2) 500 g 500 g 302922
Item
No. Part name No. used
Tightening torque
N•m kgf•cm
[27] Tapping Screws (W/Flange) D3 x 16 (Black) 9 1.3±0.3 13±3
After reassembly, check the following.
(1) Check that the Models WH 18DD and WH 18DDX run smoothly and start, stop, change speed, and
change direction securely.
(2) Check that the rotating direction of the Anvil [10] matches that of the pushed side of the Pushing Button
[30].
No-load current: 2.3±1.0 A (DC 19.8 V—equivalent to the voltage of a fully charged battery)
Tightening torque
Checking after reassembly
No-load current

-10-
• Connecting diagram
LED
M
DC-speed control switch
Battery terminal
+ (red) Controller
- (black)
LD (green)
2. Precautions on disassembly and reassembly of the charger
Refer to the Service Manual for precautions on disassembly and reassembly of the charger Models
UC 18YFSL and UC 18YKSL.
Wiring diagram
• Wiring diagram
Push the internal wire into this groove.
LED
[32]
DC-speed control switch

M O D E L
WH18DD
Rev.1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
1
21
22
23
24
25
26
27
28
34
33
29
30
32
507
509
508
510
505
511
501 502 504501
31
506
503

ITEM CODE NO.
NO. NO. USED
1 375143 GUIDE SLEEVE ASS'Y 1 INCLUD. 2-5, 9
2 330619 RETAINING RING 1
3 330856 WASHER (D) 1
4 331284 GUIDE SPRING (D) 1
5 322717 GUIDE SLEEVE (D) 1
6 337360 FRONT CAP 1
7 375003 HAMMER CASE 1
8 336639 WASHER (F) 1
9 319535 STEEL BALL D3.5 (10 PCS.) 2
*10 374395 ANVIL (A) 1
*10 374396 ANVIL (B) 1 FOR EUROPE, AUS, NZL
11 959154 STEEL BALL D5.556 (10 PCS.) 2
12 375958 HAMMER 1
13 959148 STEEL BALL D3.175 (10 PCS.) 28
14 315978 WASHER (J) 1
15 376565 HAMMER SPRING 1
16 316172 WASHER (S) 1
17 322740 STOPPER (A) 1
18 375957 SPINDLE 1
19 376564 IDLE GEAR SET (2 PCS.) 2
20 324234 NEEDLE ROLLER (A) 2
21 319911 WASHER (E) 1
22 6901VV BALL BEARING 6901VV 1
23 331858 RING GEAR (A) 1
24 334412 O-RING 1
25 329517 DAMPER (A) 2
26 374393 INNER COVER 1
27 313687 TAPPING SCREW (W/FLANGE) D3 X 16 (BLACK) 9
28 NAME PLATE 1
29 376562 WIRING ASS'Y 1 INCLUD. 31, 32
30 374399 PUSHING BUTTON 1
31 376362 DC-SPEED CONTROL SWITCH 1
32 376361 BATTERY TERMINAL 1
33 376561 HOUSING (A).(B) SET 1
*34 333352 BATTERY BSL 1815 (EUROPE) 2 INCLUD. 502
*34 334725 BATTERY BSL 1815 (CHN) 2 INCLUD. 502
*34 334726 BATTERY BSL 1815 (TPE) 2 INCLUD. 502
*34 339783 BATTERY BSL 1830C (EUROPE, AUS, NZL) 2 INCLUD. 502
*34 376029 BATTERY BSL 1850C (EUROPE, AUS, NZL) 2 INCLUD. 502
*501 CHARGER (MODEL UC18YKSL) 1
*501 CHARGER (MODEL UC18YFSL) 1
502 329897 BATTERY COVER 1
*503 992671 + DRIVER BIT (B) NO. 2 50L 1 FOR EUROPE, AUS, NZL
*504 983006 + DRIVER BIT NO. 2 65L 1 FOR CHN, TPE, SIN, MAL
505 336642 CASE 1
506 376358 HOOK SET 1
507 336471 CASE ASS'Y (STACKABLE 2) 1 INCLUD. 508-510
508 336472 LATCH 4
509 336473 HANDLE 1
510 336474 HINGE 2
511 376502 INNER TRAY 1
*601 992672 + DRIVER BIT (B) NO. 3 50L 1 FOR EUROPE, AUS, NZL
*602 983011 + DRIVER BIT NO. 3 65L 1 FOR CHN, TPE, SIN, MAL
*603 955657 - DRIVER BIT (A) 3 MM X 70L 1 FOR CHN, TPE, SIN, MAL
*604 955659 - DRIVER BIT (A) 4 MM X 70L 1 FOR CHN, TPE, SIN, MAL
*605 955674 - DRIVER BIT (A) 6 MM X 70L 1 FOR CHN, TPE, SIN, MAL
606 321823 DRILL CHUCK AND ADAPTER SET 1 INCLUD. 607, 608
607 307543 CHUCK ADAPTER 1
608 987575 CHUCK WRENCH FOR 10VLB-D,10VLR-D 1
609 309922 GREASE (ATTOLUB MS NO. 2) 500G 1
610 325149 GREASE (MOLUB-ALLOY NO. 777-1) 75G 1
611 306927 SILICONE RUBBER 1
*612 996177 NON-MAGNETIC HEX. SOCKET 8 MM 65L 1 FOR EUROPE, AUS ,NZL
*613 985329 NON-MAGNETIC HEX. SOCKET 10 MM 65L 1 FOR EUROPE, AUS, NZL
*614 996178 NON-MAGNETIC HEX. SOCKET 12 MM 65L 1 FOR EUROPE, AUS, NZL
*615 996179 NON-MAGNETIC HEX. SOCKET 13 MM 65L 1 FOR EUROPE, AUS, NZL
*616 996180 NON-MAGNETIC HEX. SOCKET 14 MM 65L 1 FOR EUROPE, AUS, NZL
*617 996181 NON-MAGNETIC HEX. SOCKET 16 MM 65L 1 FOR EUROPE, AUS, NZL
*618 996182 NON-MAGNETIC HEX. SOCKET 17 MM 65L 1 FOR EUROPE, AUS, NZL
*619 996197 HEX. SOCKET (LONG) 21 MM X 166L 1 FOR EUROPE, AUS, NZL
DESCRIPTION REMARKS
OPTIONAL ACCESSORIES
STANDARD ACCESSORIES