Hitachi DH 40MEY User manual

International Sales Division
D
LIST No.
DH 40MEY: F425
Dec. 2014
TROUBLESHOOTING GUIDE ---------------------------------------------------------------------------------------------1
1. Troubleshooting and corrective action ---------------------------------------------------------------------1
REPAIR GUIDE ----------------------------------------------------------------------------------------------------------------3
1. Precautions on disassembly and reassembly -----------------------------------------------------------3
STANDARD REPAIR TIME (UNIT) SCHEDULES ------------------------------------------------------------------ 19
CONTENTS Page
PRODUCT NAME
Hitachi Rotary Hammer
Model DH 40MEY

-1-
[Bold] numbers in the description below correspond to the item numbers in the Parts List and exploded
assembly diagram for the Model DH 40MEY.
1. Troubleshooting and corrective action
Perform troubleshooting and take a necessary corrective action according to the table below if there is a
problem that cannot be solved by the corrective action described in the Handling Instructions.
Problem Cause Check Corrective action
All the four LEDs of
the display lamp
are flashing.
• Broken Controller
Set [49] • No check needed. • Replace the Controller Set [49] with a new
one.
Three LEDs of the
display lamp are
flashing.
• Mix-up of three
internal wires of
Stator Sensor
PCB Set [42] and
Controller Set [49]
• Check the heat-shrink tube
colors (red, black, and white)
of internal wires connecting
the Stator Sensor PCB Set
[42] and Controller Set [49].
• Correctly connect
internal wires of the
Stator Sensor PCB Set
[42] and Controller Set
[49] by their tube colors
(red, black, and white).
• Broken Controller
Set [49] • Check the state of the Controller Set [49] connector. • Replace the Controller Set [49] with a new
one.
• Broken Rotor
[134] • Check the built-in magnet of
the fan for breaks. • Replace the Rotor [134] with a new one.
Two LEDs of the
display lamp are
flashing.
• Broken Controller
Set [49] • No check needed. • Replace the Controller Set [49] with a new
one.
One LED of the
display lamp is
flashing.
• Improperly
connected
connector cable of
the Stator Sensor
PCB Set [42]
• Check the plug-in state of the
connector cable.
(See “Reassembly of the
power supply unit” on page
12.)
• Firmly plug the
connector cable.
• Broken Stator
Sensor PCB Set
[42]
• When the connector cable is
not defective
• Replace the Stator
Sensor PCB Set [42]
with a new one.
• Broken Controller
Set [49] • Check the plug-in state of the Controller Set [49] connector. • Replace the Controller Set [49] with a new
one.
• Broken Rotor
[134] • Check the built-in magnet of
the fan for breaks. • Replace the Rotor [134] with a new one.
TROUBLESHOOTING GUIDE

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Problem Cause Check Corrective action
No LED of the
display lamp is ON.
• Improperly
connected
connector cable of
the Panel [112]
PCB
• Check the plug-in state of the
connector cable.
(See “Reassembly of the
power supply unit” on page
12.)
• Firmly plug the
connector cable.
• Internal wires
loosely plugged
into the Controller
Set [49] and Filter
PCB Set [58]
• Check the plug-in state of the
internal wires.
(See “Reassembly of the
power supply unit” on page
12.)
• Firmly plug the internal
wires into the Controller
Set [49] and Filter PCB
Set [58].
• Broken Controller
Set [49] • When the Controller Set [49] connector is not defective
• When the internal wire is not
defective
• Replace the Controller
Set [49] with a new
one.
• Broken LED • When the connector cable is
not defective • Replace the Panel [112] with a new one.
• Broken Filter PCB
Set [58] • When the internal wire is not defective • Replace the Filter PCB Set [58] with a new
one.
The LEDs of the
display lamp light,
but the motor does
not run.
• Internal wires
loosely connected
to the Switch [63]
• Check the plug-in state of
internal wires to the Switch
[63]. (See “Reassembly of
the power supply unit” on
page 12.)
• Firmly connect all
internal wires to the
Switch [63].
• Broken Controller
Set [49] • When internal wires of the Controller Set [49] are not
defective
• Replace the Controller
Set [49] with a new
one.
• Broken Switch
[63] • When internal wires of the
Controller Set [49] are not
defective
• Replace the Switch [63]
with a new one.

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Fig. 1
1. Precautions on disassembly and reassembly
WARNING: Be sure to disconnect the power cord plug from the wall outlet before conducting
repair. Otherwise, the motor may run suddenly and you could get injured.
1. Disassembly of the tool retainer
Remove the Front Cap [1] while pulling the Grip [2] in the arrow direction. Note that the Front Cap [1] is
firmly fitted to the Retainer Sleeve [19]. Insert the edge of a flat-head screwdriver or similar tool into the
gap between the Front Cap [1] and Grip [2], and then pry up the Front Cap [1] by placing the fulcrum on
the Grip [2] as shown below. You can now separate the Grip [2] from the Retainer Sleeve [19].
Remove the Stopper Ring [3] by using a retaining ring puller. You can now separate the Retainer
Washer [4], Retainer Damper (A) [5], Bit Lock Holder [6], two Bit Locks [18], Thrust Plate [7], Retainer
Spring [8], and Spring Holder (A) [9] from the Retainer Sleeve [19].
2 Disassembly of the hammering mechanism
(1) Second hammer and striker
First, remove the Bolt M5 x 12 [10] from the Cylinder Case Cover [11] and detach the Cylinder Case
Cover [11] from the Cylinder Case [13]. Remove the Bolt M6 x 25 [12] and detach the Cylinder Case
[13] from the Crank Case [89]. You can now separate Spring Holder (B) [28], Retainer Sleeve [19],
and other parts from the main body.
You can take out the Second Hammer [21] together with the Damper Holder [24], Damper [23], and
Damper Washer [22] from the detached Retainer Sleeve [19].
You can take out the Cylinder [25] together with the Lock Spring [29], Lock Sleeve [30], Clutch Spring
[31], and Clutch [32] from the main body.
Strike the end of the Cylinder [25] with a plastic hammer to pull out the Striker [26].
Disassembly
REPAIR GUIDE
[3]
Flat-head screwdriver
[19]
[2]
[1]
[4] [6] [7]
[5] [18]
[9]
[8]
Fig. 2

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Fig. 3
Fig. 4
(2) Piston ass’y
You can remove the piston ass’y from the main body without disassembling the Bevel Gear [34] and
Slip Clutch Ass’y [114]. Move the Connecting Rod Ass’y [39] as shown below to remove the piston
ass’y from the Crank Shaft [83].
[19]
Cylinder case ass'y
[21]
[26] [25]
[23] [24]
[22]
[29]
[28]
Crank case ass'y
[31] [30] [32] [33]
[17]
[15] [16]
[34] [39] [83]
Piston ass’y

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Fig. 5
(3) First gear and crank shaft
Remove the Bolt M5 x 16 [66] and detach the Crank Cover [101] from the Crank Case [89]. Then take
out the Change Plate [105] and Slider [33] from the Crank Case [89].
Remove the Bolt M5 x 16 [66] and Bolt M5 x 12 [53], and then detach Handle (A) [64], Handle (B) [55],
and the Back Cover [60].
Remove the Bolt M6 x 45 [45] and Bolt M6 x 20 [131], and then detach the Crank Case [89] from the
Housing [48]. Disconnect the Panel [112] connector from the Controller Set [49] beforehand.
If the Slip Clutch Ass’y [114] is difficult to remove from the Crank Case [89] or Gear Cover [130], strike
it with a plastic hammer to remove it.
Wipe off grease from the Piston [38] side and the First Gear [128] side in the Crank Case [89], and
then remove the Retaining Ring [85] that retains the Ball Bearing 6203DD [87] by a retaining ring
puller, while turning the Crank Shaft [83] so that you can see the Retaining Ring [85] hole.
Place the Crank Case [89] on an adequate cradle with its Piston [38] facing down, and then use a
hand press to press down on the end surface of the Crank Shaft [83]. The First Gear [128] and Crank
Shaft [83] can be removed from the Crank Case [89].
(4) Slip clutch ass’y
Remove the Ball Bearing 629VV [126] by using
a bearing puller. Support Washer (A) [120] by
an adequate sleeve-like cradle as shown below.
Use a hand press to press the Bevel Pinion
[115] on the Spacer [125] side. Detach the
Gear Holder [121] and Spacer [125] from the
Bevel Pinion [115]. When removing the Second
Gear [124] from the Gear Holder [121], put
these parts in a plastic bag and disassemble in
the bag to avoid losing Spring (C) [123] and the
Needle [122].
[89] [83]
[85]
[89]
[83]
[128]
Adequate cradle
Hand press
Fig. 6
[126]
Cradle
[120]
[124]
[115]
[125]
[121]
[123]
Hand press
[122]

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Fig. 7
3. Disassembly of the motor
Firmly hold the Housing [48] and use a plastic
hammer to tap the shaft of the Rotor [134] until the
spigot joint of the Gear Cover [130] is removed from
the Housing [48].
The Rotor [134] has strong magnetic force. Firmly
hold the Housing [48] and pull out the Gear Cover
[130] from the Housing [48].
[130]
[48]
[134]
Tap the shaft of the rotor.

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Fig. 8
Fig. 9
Reassembly can be accomplished by reversing the disassembly procedure. However, special attention
should be given to the following items.
1. Reassembly of the hammering mechanism and low vibration mechanism
(1) First gear and crank shaft
Press-fit Oil Seal (B) [88] to the Crank
Case [89]. Mount the O-ring [86].
Press-fit the Ball Bearing 6203DD [87].
Use a retaining ring puller to mount the
Retaining Ring [85].
Press-fit the Crank Shaft [83] to the Ball
Bearing 6203DD [87].
Insert the Feather Key [84] into the
Crank Shaft [83] groove. Support the
plane of the Crank Shaft [83] with an
adequate steel rod and use an adequate
tool to press-fit the First Gear [128].
Prior to press-fitting, make sure the
Feather Key [84] matches the key
groove of the First Gear [128].
(2) Piston
Insert the Connecting Rod Ass’y [39] into the Piston [38], and then press-fit the Piston Pin [37] from
the D8 hole (marked “ĭ2”) of the Piston [38]. Be careful not to let the Piston Pin [37] project from the
outer diameter of the Piston [38]. Mount the O-ring [36] on the Piston [38] to make the piston ass’y.
Next, turn the Crank Shaft [83] to the position shown below, and then mount the piston ass’y to the
Crank Shaft [83] from the Cylinder Case [13] side of the Crank Case [89].
The piston ass’y can be assembled even when the Bevel Gear [34] and Slip Clutch Ass’y [114] are
mounted to the Crank Case [89].
Reassembly
[84][89]
Adequate
steel rod
[128]
[88]
[86] [87] [83] [85]
[83]
[89]
[39]
[38][36]
[37] “ĭ2” mark
Adequate tool

-8-
Fig. 10
(3) Cylinder and retainer sleeve
Mount the Retainer Damper Washer [17], Retainer Damper (B) [16], and the Retainer Damper Holder
[15] in this order to the Retainer Sleeve [19] with the rounded surface of the Retainer Damper Washer
[17] facing that of the Retainer Sleeve [19] and the rounded surface of the Retainer Damper Holder
[15] facing that of the Retainer Sleeve [19].
Insert the Second Hammer [21] (equipped with O-ring (C) [20]), Damper Washer [22], Damper [23],
and Damper Holder [24] in this order with the rounded surface of the Damper Washer [22] facing that
of the Second Hammer [21].
Insert the assembled Retainer Sleeve [19] into the Cylinder Case [13]. Be careful not to curl the lip of
the oil seal.
Insert the Slider [33] into the outer periphery of the Bevel Gear [34] along the Crank Case [89] groove.
As shown below, push in the Slider [33] until its stopper contacts the butting position of the Crank Case
[89]. Insert so that the Clutch [32] engages with the internal claw of the Bevel Gear [34].
Insert the Striker [26] equipped with the O-ring [27] into the Cylinder [25]. Fit the Clutch Spring [31] to
the Cylinder [25], and then insert the assembled Cylinder [25] into the Crank Case [89].
Next, insert the Lock Sleeve [30] into the Crank Case [89] with the inner spline groove of the Crank
Case [89] matched with the Lock Sleeve [30] spline. Then place the Lock Spring [29] and Spring
Holder (B) [28] on the Lock Sleeve [30].
Finally, fit the protrusion of the Retainer Sleeve [19] to the Cylinder [25] groove, and then assemble the
Cylinder Case [13] equipped with the Retainer Sleeve [19] with the Crank Case [89] equipped with the
Cylinder [25].
[19]
[13] [15] [16] [17]
[24][23]
[22]
[25] [31] [28] [30] [32] [33] [34]
[26] [29]
[35]
Note directions of [15],
[17], and [22].
[21]
[27]
[20]
Do not curl the
oil seal lip.

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Fig. 11
Fig. 12
(4) Slip clutch ass’y
Press-fit the Collar [116] and Ball Bearing 6002DD [118] in this order to the Bevel Pinion [115], and
then insert the Washer [119] and Washer (A) [120] in this order. Mount the Feather Key [94] to the
Bevel Pinion [115] and press-fit the Gear Holder [121]. Insert the Second Gear [124] into the outer
periphery of the Gear Holder [121]. Apply Hitachi Motor Grease No. 29 to the inner periphery of the
Second Gear [124] in advance. Insert the ten Needles [122] upright as shown below, and then push in
ten Springs (C) [123]. Fill up the slotted groove and through-hole portions of the Gear Holder [121]
with Hitachi Motor Grease No. 29, and then press-fit the Spacer [125] and Ball Bearing 629VV [126] in
this order to the Bevel Pinion [115].
(5) Handle shaft and handle (A)
Push the Holder [73] into the Back Cover [60]
by hand. Make sure the gap of the Holder [73]
is at the bottom and the Holder [73] does not
protrude from the surface of the Back Cover
[60]. Make sure the convex mark on the Back
Cover [60] is aligned with the convex mark on
the Handle Shaft [74]. Assemble the Handle
Shaft [74] and push the four Handle Dampers
[56] into the gap between the Holder [73] and
Handle Shaft [74]. Make sure the Handle
Dampers [56] do not protrude from the end
surface of the Back Cover [60].
To mount Handle (A) [64] and Handle (B) [55],
rotate the Handle Shaft [74] about 10°, and
then fit the Transatory Unit [57] and Handle
Shaft [74] to Handle (A) [64] and Handle (B)
[55] simultaneously.
[115]
[120]
[124] [126] [125]
[118]
[116]
[115]
[121] [122]
[123]
[94]
A
A
Slotted groove in
the gear holder Section A—A
[119]
Convex mark
Gap portion
[73]
[56]