Hitachi DH 40MC User manual

Overseas Sales Division
D
REPAIR GUIDE -----------------------------------------------------------------------------------------------------------------1
1. Precautions on disassembly and reassembly ------------------------------------------------------------1
• Disassembly ----------------------------------------------------------------------------------------------------1
• Reassembly -----------------------------------------------------------------------------------------------------4
• Lubrication points and types of lubricant -----------------------------------------------------------------8
• Tightening torque ----------------------------------------------------------------------------------------------9
• Insulation test ---------------------------------------------------------------------------------------------------9
• No-load current value -----------------------------------------------------------------------------------------9
• Connecting diagram ---------------------------------------------------------------------------------------- 10
STANDARD REPAIR TIME (UNIT) SCHEDULES ------------------------------------------------------------------- 11
CONTENTS Page
PRODUCT NAME
Hitachi Rotary Hammer
Model DH 40MC
CONFIDENTIAL
LIST No.
DH 40MC: F440
Dec. 2016

-1-
Fig. 1
[11]
[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.
[Bold] numbers in the description below correspond to the item numbers in the parts list and exploded
assembly diagram for the Model DH 40MC.
1. Disassembly of the tool retainer
• Forcibly pull out the Front Cap [1] from the Retainer Sleeve [28] while pulling the Grip [11] in the arrow
direction as shown in Fig. 1.
• Remove the Stopper Ring [2] by using a retainer ring puller. Then the Grip [11], Retainer Washer [3],
Retainer Damper (A) [4], Bit Lock Holder [12], two Bit Locks [27], Thrust Plate [13], Retainer Spring [14]
and Spring Holder (A) [15] can be removed from the Retainer Sleeve [28] (Fig. 2).
2. Disassembly of the hammering mechanism
(1) Removing the second hammer and striker
• Remove the Hex. Socket Hd. Bolt M6 x 25 [21] to remove the Cylinder Case [22], Spring Holder (B)
[37], Retainer Sleeve [28] and other parts from the main body.
• Remove the Second Hammer [30] from the Retainer Sleeve [28] together with the Damper Holder [33],
Damper [32] and Damper Washer [31].
• Pull out the Cylinder [36] from the main body together with the Lock Spring [38], Lock Sleeve [39],
Clutch Spring [40] and Clutch [41].
• Remove the Striker [34] by tapping the end surface of the Cylinder [36] with a plastic hammer.
[12]
[28] [2] [4]
[27] [13] [14]
Fig. 2
REPAIR GUIDE
Disassembly
[3] [15]
[11]

-2-
Fig. 3 • Removing the second hammer and striker
[28]
[31]
[32]
[33]
[30]
[37]
[22]
[24]
[36]
[34]
[39]
[38]
[40]
[41]
[85]
[47]
[48]
[25] [26]
Fig. 4 • Removing the piston ass’y
[43]
Piston ass’y
[48] [85]
(2) Removing the piston ass’y
• Remove the Hex. Socket Hd. Bolt M5 [110] from the Crank Cover [111]. Detach the Crank Cover [111]
and the assembly of the Lever Shaft Holder [116] from the Crank Case Ass'y [91].
• Remove the Change Plate [119] from the Crank Case Ass'y [91].
• The piston ass’y can be removed from the main body without removing the Bevel Gear [43] and Slip
Clutch Ass’y [93]. Move the Connecting Rod [48] as shown below to remove the piston ass’y from the
Crank Shaft [85].

-3-
Fig. 5 • Removing the first gear and crank shaft
[123]
[91]
[88] Release the Retaining
Ring for D40 Hole [101]
from the groove.
[85]
[85]
[87]
(3) Removing the first gear and crank shaft
• Remove the Hood [126] from the Crank Case Ass'y [91] by removing the Hex. Socket Hd. Bolt M5 x 12
[127] from the Hood [126].
• Remove the Seal Lock Hex. Socket Hd. Bolt M6 x 20 [109], Seal Lock Hex. Socket Hd. Bolt M6 x 45
[92], Hex. Socket Hd. Bolt M5 x 16 [75] and Tapping Screw D5 x 20 [65].
• Separate the Crank Case Ass'y [91] from the Housing Ass'y [55], Handle [76], and Gear Cover [108].
• Remove the Slip Clutch Ass'y [93] from the Crank Case Ass'y [91].
NOTE: Remove the Slip Clutch Ass'y [93] from the Crank Case Ass'y [91] beforehand because
the Bevel Gear [43] cannot be removed if the Slip Clutch Ass'y [93] remains in the Crank
Case Ass'y [91].
• Remove grease from the Piston [47] side and First Gear [123] side of the Crank Case Ass'y [91].
• Use a retaining ring puller to remove the Retaining Ring for D40 Hole [87] fixing the Ball Bearing
6203DD [88].
NOTE: At this time, turn the Crank Shaft [85] to expose the hole of the Retaining Ring for D40
Hole [87] prior to removal.
• Use a hand press to press the end face of the Crank Shaft [85], and then remove the First Gear [123]
and Crank Shaft [85] from the Crank Case Ass'y [91] as shown in Fig. 5.
(4) Disassembly of the slip clutch ass’y
• Remove the Ball Bearing 629VV [106] by using
a bearing puller.
• Support Washer (A) [100] by an adequate
sleeve-like cradle as shown in Fig. 6.
• Use a hand press to press the Bevel Pinion [94]
on the Spacer [105] side.
• Detach the Gear Holder [102] and Spacer [105]
from the Bevel Pinion [94].
• When removing the Second Gear [101] from
the Gear Holder [102], put these parts in a
plastic bag and disassemble in the bag to avoid
losing Spring (C) [103] and Needle [104].
Adequate cradle
Hand press
Fig. 6 • Disassembly of the slip clutch ass'y
[106]
Cradle
[100]
[101]
[94]
[105]
[102]
[103]
Hand press
[104]
[91]

-4-
Fig. 8 • Mounting the piston
Fig. 7 • Mounting the first gear and crank shaft
[46]
[48]
[47]
[85]
[45]
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
(1) Mounting the first gear and crank shaft
• Press-fit Oil Seal (B) [90] to the Crank Case Ass'y
[91].
• Mount the O-ring (S-40) [89].
• Press-fit the Ball Bearing 6203DD [88].
• Use a retaining ring puller to mount the Retaining
Ring for D40 Hole [87].
• Press-fit the Crank Shaft [85] to the Ball Bearing
6203DD [88].
• Insert the Feather Key 3 x 3 x 8 [86] into the
Crank Shaft [85] groove.
• Support the plane of the Crank Shaft [85] with an
adequate steel rod and use an adequate tool to
press-fit the First Gear [123].
NOTE: Prior to press-fitting, make sure the
Feather Key 3 x 3 x 8 [86] matches the
key groove of the First Gear [123].
(2) Mounting the piston
• Insert the Connecting Rod [48] into the Piston [47], and then press-fit the Piston Pin [46] from the D8
hole (marked side) of the Piston [47].
NOTE: Be careful not to let the Piston Pin [46] project from the outer diameter of the Piston [47].
• Mount the O-ring [45] on the Piston [47] to make the piston ass’y.
• Next, turn the Crank Shaft [85] to the position shown below, and then mount the piston ass’y to the
Crank Shaft [85] from the Cylinder Case [22] side of the Crank Case Ass'y [91].
NOTE: The piston ass’y can be assembled even when the Bevel Gear [43] and Slip Clutch
Ass’y [93] are mounted to the Crank Case Ass'y [91].
Reassembly
[87]
[86]
Adequate steel rod
[89]
[85]
[91]
“Φ2” concavity mark
Adequate tool
[123]
[90]
[88]

-5-
Fig. 9 • Mounting the cylinder and retainer sleeve
[28]
[30]
[38]
[40]
[33]
[31]
[24]
[48]
[32]
[85]
[22]
[39]
[41]
[47]
[25] [26]
[34]
[37]
[42] [44] [43]
Be careful of the mounting direction.
Be careful of the mounting direction.
(3) Mounting the cylinder and retainer sleeve
• Mount the Retainer Damper Washer [26], Damper Sleeve [25], and Retainer Damper (B) [24] to the
Retainer Sleeve [28] in this order, while aligning the rounded surface of the Retainer Damper Washer
[26] with the rounded surface of the Retainer Sleeve [28].
• Insert the Second Hammer [30] (equipped with O-ring (C) [29]), Damper Washer [31], Damper [32],
and Damper Holder [33] into the Retainer Sleeve [28] in this order, while aligning the rounded surface
of the Damper Washer [31] with the rounded surface of the Second Hammer [30].
• Insert the assembly of the Retainer Sleeve [28] into the Cylinder Case [22].
NOTE: Be careful not to curl the lip of the oil seal.
• After inserting the Thrust Washer [44] and the Bevel Gear [43] into the Crank Case Ass'y [91], insert
the Slider [42] into the outer periphery of the Bevel Gear [43] along the Crank Case Ass'y [91] groove.
NOTE: The Bevel Gear [43] cannot be inserted if the Slip Clutch Ass'y [93] is mounted to the
Crank Case Ass'y [91] on ahead.
• Insert the Clutch [41] so that it engages with the internal claw of the Bevel Gear [43].
• Insert the Striker [34] equipped with the O-ring [35] into the Cylinder [36]. Fit the Clutch Spring [40] to
the Cylinder [36], and then insert the assembly of the Cylinder [36] into the Crank Case Ass'y [91].
• Insert the Lock Sleeve [39] into the Crank Case Ass'y [91], while aligning the inner spline groove of the
Crank Case Ass'y [91] with the Lock Sleeve [39] spline.
• Place the Lock Spring [38] and Spring Holder (B) [37] on the Lock Sleeve [39].
• Fit the protrusion of the Retainer Sleeve [28] in the Cylinder [36] groove, and then mount the Cylinder
Case [22] equipped with the Retainer Sleeve [28] to the Crank Case Ass'y [91] equipped with the
Cylinder [36].

-6-
Fig. 10 • Reassembly of the slip clutch ass'y
Fig. 11 • Mounting the lever shaft holder
[112]
[116]
[113]
[114]
[115]
[118]
(4) Reassembly of the slip clutch ass’y
• Press-fit the Collar [96] and Ball Bearing 6002DD [98] in this order to the Bevel Pinion [94], and then
insert the Washer [99] and Washer (A) [100] in this order.
• Mount the Feather Key 3 x 3 x 8 [95] to the Bevel Pinion [94] and press-fit the Gear Holder [102].
• Insert the Second Gear [101] into the outer periphery of the Gear Holder [102]. Apply Hitachi Motor
Grease No. 29 to the inner periphery of the Second Gear [101] in advance.
• Insert the ten Needles [104] upright as shown below, and then push in ten Springs (C) [103].
• Fill up the slotted groove and through-hole portions of the Gear Holder [102] with Hitachi Motor Grease
No. 29, and then press-fit the Spacer [105] and Ball Bearing 629VV [106] to the Bevel Pinion [94] in
this order.
(5) Mounting the lever shaft holder
• Apply Hitachi Motor Grease No. 29 to the O-ring (S-18) [115], and then attach the O-ring to the Change
Lever [112]. Insert the Lever Spring [113] into the change lever hole.
• Apply Hitachi Motor Grease No. 29 to the Steel Ball D4.76 [114] and place it into the concave portion of
the Lever Shaft Holder [116].
• Position the Lever Spring [113] and Steel Ball D4.76 [114] properly. Insert the Change Lever [112] into
the hole of the Lever Shaft Holder [116] and fix it with the Retaining Ring for D20 Shaft [118].
NOTE: Rotate the Change Lever [112] to check that the lever clicks at each mode position.
Insert the Change Lever [112] into the Lever Shaft Holder [116] straight to avoid
damaging the O-ring.
[94]
[100]
[101]
[106]
[105]
[98]
[96]
[94]
[101] [104]
[103]
[95]
A
A
Slotted groove in
the gear holder
Section A—A
[99]
[102]

-7-
Fig. 12 • Inserting the change plate
[119]
[42]
Stepped portion of the Change Plate [119]
Notch of the Slider [42]
(6) Mounting the crank cover
• Insert the stepped portions of the Change Plate [119] into the notches of the Slider [42].
NOTE: Be careful of the inserting direction. See the figure below.
• Mount the Cylinder O-ring [117] to the outer diameter portion on the bottom of the Lever Shaft Holder
[116]. Set the Change Lever [112] to "Rotation + Hammering" mode position.
• Put the assembly of the Lever Shaft Holder [116] and Crank Cover [111] on the Crank Case Ass'y [91]
and fix them with the Hex. Socket Hd. Bolts M5 [110].
NOTE: After tightening the Hex. Socket Hd. Bolts M5 [110], check the following:
• The Change Lever [112] rotates smoothly.
• The Retainer Sleeve [28] is kept from rotating when the Change Lever [112] is set to
"Hammering" mode.
• The Retainer Sleeve [28] rotates smoothly when the Change Lever [112] is set to
"Neutral" mode.

-8-
Fig. 13 • Specified grease (for hammer and hammer drill)
Specified grease (for hammer and hammer drill)
• Fill 20 g of specified grease in the Cylinder Case [22].
• Fill 69 g of specified grease in the Crank Case Ass'y [91] on the Connecting Rod [48] side.
• Apply specified grease to the inside and outside of the Cylinder [36].
• Apply specified grease to the inner diameter portion of the Connecting Rod [48].
• Apply specified grease to the sliding portion of the Second Hammer [30] and O-ring (C) [29] of the
Second Hammer [30].
• Apply specified grease to the sliding portion of the Striker [34] and O-ring [35] of the Striker [34].
• Apply specified grease to the outer diameter portion of the Piston [47] and O-ring [45] of the Piston
[47].
• Apply specified grease to the inner lips of Oil Seal (A) [97].
• Apply specified grease to the inner lips of Oil Seal (B) [90].
• Apply specified grease to the inner and outer diameter portions of the Bevel Gear [43].
• Apply specified grease to the Thrust Washer [44].
• Apply specified grease to the inner lip of the Oil Seal [20].
• Apply specified grease to the inside of the Clutch [41].
• Apply specified grease to the Damper [32].
• Apply specified grease to Retainer Damper (B) [24].
Hitachi Motor Grease No. 29
• Fill a total of 20 g of Hitachi Motor Grease No. 29 in the Crank Case Ass'y [91] on the First Gear [123]
side and the Gear Cover [108] side.
• Fill a total of 5 g of Hitachi Motor Grease No. 29 in the slotted groove and the 6 mm dia. holes of the
Gear Holder [102].
• Apply Hitachi Motor Grease No. 29 to the Needle Bearing [124].
• Apply Hitachi Motor Grease No. 29 to the pinion portion of the Armature [74].
• Apply Hitachi Motor Grease No. 29 to the Bit Lock [27].
CAUTION: Both viscosity and consistency of the specified grease are optimized for the
rotary hammer Model DH 40MC in order to prolong the service life. Therefore,
applying ordinary grease intended for other models to the Model DH 40MC may
dramatically shorten the product’s service life.
Net weight Code No.
500 g 980927
70 g 308471
30 g 981840
Lubrication points and types of lubricant
30 g
500 g 70 g

-9-
CAUTION: Be sure to apply TB1401 screw locking agent to the threads of the following screws and
bolts before tightening. Otherwise, the screw or bolt loosened by vibration may cause
damage to the tool body.
Item No. Part name No.
used
Tightening torque
N•m lbf-ft
[21] Hex. Socket Hd. Bolt (W/Flange) M6 x 25 4 10 to 12 7.4 to 8.9
[50] Hex. Hd. Tapping Screw D5 x 55 2 3.0 ± 0.5 2.2 ± 0.4
[65] Tapping Screw (W/Flange) D5 x 20 (Black) 4 3.0 ± 0.5 2.2 ± 0.4
[75] Hex. Socket Hd. Bolt (W/Flange) M5 x 16 2 6 to 8 4.4 to 5.9
[80] Tapping Screw (W/Flange) D4 x 25 (Black) 2 2.0 ± 0.5 1.5 ± 0.4
[84] Tapping Screw (W/Flange) D4 x 16 2 2.0 ± 0.5 1.5 ± 0.4
[92] Seal Lock Hex. Socket Hd. Bolt M6 x 45 4 10 to 12 7.4 to 8.9
[109] Seal Lock Hex. Socket Hd. Bolt M6 x 20 2 10 to 12 7.4 to 8.9
[110] Hex. Socket Hd. Bolt (W/Flange) M5 x 18 4 8 to 10 5.9 to 7.4
[121] Cap Screw 1 7 to 9 5.2 to 6.6
[127] Hex. Socket Hd. Bolt (W/Flange) M5 x 12 1 4.0 ± 0.5 3.0 ± 0.4
After completing disassembly and repair, measure the insulation resistance and dielectric strength.
Insulation resistance: 7 MΩor higher (as measured with a 500 VDC megohm tester)
Dielectric strength: 4,000 VAC/1 minute, with no abnormalities ----- 220 V – 240 V
(and 110 V for UK products)
2,500 VAC/1 minute, with no abnormalities -----110 V – 127 V
(exceptUKproducts)
After no-load operation for 30 minutes, the no-load current values should be as follows:
Voltage 110 V 120 V 127 V 220 V 230 V 240 V
Current max. 6.5 A 5.9 A 4.6 A 3.4 A 3.3 A 3.2 A
Tightening torque
No-load current value
Insulation test