Hitachi DH 24PG Assembly instructions

LIST Nos.
DH 24PG: F420
DH 26PB: F417
DH 28PBY: F414
May 2013
PRODUCT NAME
Hitachi Rotary Hammer
Models DH 24PG
DH 26PB
DH 28PBY
D
DH 28PBY
Sales Division
REPAIR GUIDE

---------------------------------------------------------------------------------------------------------------- 1
1. Precautions on disassembly and reassembly ----------------------------------------------------------- 1
STANDARD REPAIR TIME (UNIT) SCHEDULES ------------------------------------------------------------------ 19
CONTENTS Page

-1-
Be sure to disconnect the power cord plug from the power supply before conducting repair. Otherwise, the
motor may suddenly turn on, posing a very dangerous situation.
1. Precautions on disassembly and reassembly
(Bold) numbers in the descriptions below correspond to item numbers in the Parts List and exploded
assembly diagram for the Model DH 24PG, <Bold> numbers to those for the Model DH 26PB, and {Bold}
numbers to those for the Model DH 28PBY. [Bold] numbers correspond to item numbers for the Models
DH 24PG, DH 26PB, and DH 28PBY.
1. Disassembling the tool retainer ass’y
Fully pull the Grip [3] in the arrow direction and detach the Front Cap [1].
Then use the retaining ring puller to remove the Stopper Ring [2], while pulling the Grip [3] in the arrow
direction. You can now detach the Grip [3], Ball Holder [4], Steel Ball D7.0 [19], Holder Plate [5], and
Holder Spring [6] from the Cylinder [20].
Disassembly
REPAIR GUIDE
Fig. 1 ƔDisassembling the tool retainer ass’y
Grip [3]
Front Cap [1] Holder Plate [5]
Ball Holder [4]
Stopper Ring [2]
Cylinder [20]
Steel Ball D7.0 [19]
Grip [3]
Holder Spring [6]

-2-
Fig. 2 ƔRemoval of the change lever
Change Lever (13)<12>{12} Pushing Button [11] pin route
2. Removing the change lever
Push in the Pushing Button [11] at the "Rotation + Hammering" ( mark) position, turn the Change
Lever (13)<12>{12} counterclockwise a little, and then fully push in the Pushing Button [11]. In this state,
turn the Change Lever (13)<12>{12} clockwise. When the lever stops, release the Pushing Button [11]
and then turn the Change Lever (13)<12>{12} clockwise. When the lever stops again, push in the Pushing
Button [11] and then turn the Change Lever (13)<12>{12} clockwise once more. At this position, ply up
the Change Lever (13)<12>{12} in order to remove it.

-3-
Fig. 3 ƔDisassembling the hammering mechanism
Hand press
Rear end of the Second Shaft [41]
Clutch [44] end face
Clutch
[
44
]
end face
3. Disassembling the hammering mechanism
Use a drill bit or screwdriver to push in the Second Hammer [30], and then remove the Striker [36] that is
chucked by O-ring (C)[33]. Remove the Tapping Screw (W/Flange) D5 x 35 (66)<66>{76} from the
Housing (65)<65>{75} and then detach the Gear Cover [7]. Do not let the Inner Cover [53] come off from
the Housing (65)<65>{75}. Otherwise, the Armature (59)<59>{65} will come off together with the Inner
Cover [53], thereby damaging its carbon brushes and the commutator.
Remove the Seal Lock Hex. Socket Hd. Bolt M5 x 16 [48] from the Bearing Holder [49], rotate the Second
Shaft [41] to allow the Piston [38] to reach the top dead point (towards the Inner Cover [53]). The
Reciprocating Bearing [47] arm comes off from the Piston Pin [39] and parts on the Second Shaft [41]
come off together from the Inner Cover [53]. The Seal Lock Hex. Socket Hd. Bolt M5 x 16 [48] loses its
bonding force when disassembled. Accordingly, it must be replaced by a new one when reassembled.
Hold the end face of the Clutch [44] as shown below, use a hand press to push the rear end of the
Second Shaft [41] in order to push out the First Gear [51], Bearing Cover [50], Ball Bearing
608VVC2PS2L [17], Bearing Holder [49], Bearing Washer [18], Reciprocating Bearing [47], Clutch [44],
Change Plate [46], Washer [45], Clutch Spring [43], and Washer (C) [42] from the Second Shaft [41].
Note that the First Gear [51] is press-fitted to the rear end of the Second Shaft [41] for alignment.

-4-
4. Disassembling the cylinder ass’y
(1) Disassembly of the slip clutch ass’y
Remove the tool retainer ass’y and pull out the Cylinder [20] ass’y from the Gear Cover [7]. Remove
Washer (A) [25] from the Cylinder [20] and then use the retaining ring puller to pull out the Retaining Ring
for D30 Shaft [26]. Washer (A) [25], Spring (A) [24], the Second Gear [23], Cylinder Clutch [22], and Pin
D2.5 [21] can now be removed from the Cylinder [20].
(2) Disassembly of the cylinder inside
Insert stopper ring jig (A) (J-341) into the Cylinder [20] from the non-hole side as shown in Fig. 4 until it
contacts the end of the Damper Holder [34]. Clamp the ends of the Cylinder [20] and stopper ring jig (A)
(J-341) with a vise to compress Damper (A) [32]. (Push the Stopper Ring [35] with punch (C) (J-341) and
make sure it moves a little.) In this state, insert punch (C) (J-341) into each of the two ĭ8 holes on the
Cylinder [20]. Hammer the punch head to give force to the periphery of the Stopper Ring [35] in order to
detach the ring from the bore groove of the Cylinder [20]. Fully hammer along the periphery of the Stopper
Ring [35] until the Stopper Ring [35] disappears from the two ĭ8 holes.
Then unclamp the Cylinder [20] from the vise and use ring puller jig (B) (J-341) to pull out the Stopper
Ring [35] from the inner circumference of the Cylinder [20]. Be careful not to let the Stopper Ring [35] pop
out. Once the Stopper Ring [35] is detached from the Cylinder [20], Hammer Holder (C) [28], Sleeve (FW)
[29], the Second Hammer [30], Hammer Holder (A) [31], Damper (A) [32], O-ring (C) [33], and the
Damper Holder [34] can be removed from the Cylinder [20]. Here the Stopper Ring [35] is deformed by
disassembly and must be replaced by a new one when reassembled. Replace O-ring (C) [33] with a new
one at each disassembly to prevent dry firing.
Fig. 4 ƔDisassembling the cylinder ass’y
Hammer the punch head.
Punch
(
C
)
(
J-341
)
ĭ8 hole (2 holes)
Vise
Vise
Damper (A) [32]
Sleeve (FW) [29]
Hammer Holder (A) [31]
Hammer Holder (C) [28]
Stopper ring jig (A) (J-341)
Second Hammer [30] O-ring (C) [33]
Damper Holder [34]
Stopper Ring [35]

-5-
Reassembly can generally be conducted by reversing the disassembly procedure. However, special
attention should be given to the following items.
1. Reassembling the cylinder ass’y
Insert the set of Hammer Holder (C) [28], Sleeve (FW) [29], the Second Hammer [30], Hammer Holder
(A) [31], Damper (A) [32], O-ring (C) [33], and the Damper Holder [34] into the Cylinder [20] to which Oil
Seal (A) [27] is press-fitted. (Do not reverse the seal orientation.) (Assemble with the bore slope of
Hammer Holder (C) [28] set at the rear end and with the Sleeve (FW) [29] notch set at the front end as
shown in Fig. 5. Do not reverse the assembly order.) Push a new Stopper Ring [35] into the Cylinder [20]
with the break of the Stopper Ring [35] facing away from the ĭ8 hole on the Cylinder [20] as shown in Fig.
5. With the ring break facing toward the ĭ8 hole, the cylinder assembly is difficult to disassemble. Note the
ĭ8 hole on the Cylinder [20] and correctly orient the Stopper Ring [35] as shown in Fig. 5 when pushing in.
Insert stopper ring jig (A) (J-341) from the hole side and use a hand press to press against the upper end
of the jig until the Stopper Ring [35] is fitted into the bore groove of the Cylinder [20]. Confirm that the
Stopper Ring [35] is fit securely into the bore groove of the Cylinder [20] through the two ĭ8 holes on the
periphery of the Cylinder [20].
Reassembly
Fig. 5 ƔInside structure of the cylinder ass’y
Hand press
Second Hammer [30]
Hammer Holder (C) [28]
Hammer Holder (A) [31]
Damper (A) [32]
Sleeve (FW) [29]
ĭ8 hole (2 holes)
Damper Holder [34]
O-ring (C) [33]
Stopper ring jig (A) (J-341)
Stopper Ring [35]
Oil Seal (A) [27]
Sleeve (FW) [29] notch
Cylinder [20]
ĭ8 hole
ĭ8 hole
Stopper Ring [35] break
Bore slope of Hammer Holder (C) [28]

-6-
2. Press-fitting the first gear
Match the end of the First Gear [51] with the rear end of the Second Shaft [41] and then press-fit. After
press-fitting the First Gear [51], confirm that the inner ring of the Reciprocating Bearing [47] shaft rotates
smoothly.
3. Mounting the oil seals
In reassembly of the Oil Seal [9] and Oil Seal (A) [27], apply grease to the inner circumferences of both
seals, but do not apply grease along their peripheries. Be careful not to skew the Oil Seal [9] and Oil Seal
(A) [27] when press-fitting these parts.
4. Reassembling the internal pressure adjusting mechanism
Insert Felt Packing (A) (64)<64>{71} into the hole on the Air Cap (63)<63>{70} and lay the Air Cap
(63)<63>{70} over the ĭ8.4 shaft of the Inner Cover [53]. Fit the inside boss of the Air Cap (63)<63>{70}
hole to the groove on the ĭ8.4 shaft of the Inner Cover [53].
Fig. 6 ƔReassembling the internal pressure adjusting mechanism
Air Cap (63)<63>{70}
Felt Packing (A) (64)<64>{71}
Fit the boss to the groove.
Inner Cover [53]
A – A (2:1)
A
A

-7-
5. Reassembling the low vibrations mechanism (DH 28PBY)
Degrease Weight Damper (A) <54> bonding area of the Inner Cover <53> and then bond Weight Damper
(A) <54> to the area. Degrease the threaded portion of Weight (A) <55>, mount Weight (B) <57> and the
Leaf Spring <56> on Weight (A) <55>, and then secure both parts with the Seal Lock Hex. Socket Hd. Bolt
M3 x 8 <58>. Degrease the threaded portion of the Inner Cover <53>. Insert the Spring Damper <72> into
the Inner Cover <53> and Spring Holder <73>, and then secure the Leaf Spring <56> and Spring Holder
<73> with the Seal Lock Hex. Socket Hd. Bolt M4 x 12 <74>. Place Weight (A) <55> on the Inner Cover
<53> side and Weight (B) <57> on the Housing <75> side. Do not reverse the positions.
Degrease Weight Damper (B) <66> bonding area of the Fan Guide <67> and bond Weight Damper (B)
<66> to the area. Mount the Cover Plate <64> before inserting the Armature <65> into the Inner Cover
<53>. Mount the Cover Plate <64> with its body projected toward the Inner Cover <53> as shown in Fig. 7.
Fit the projection of the Inner Cover <53> into the hole on the Cover Plate <64>.
Fig. 7 ƔReassembling the low vibrations mechanism
Inner Cover <53>
Weight Damper (A) <54> bonding area
Weight Damper (B) <66> bonding area
Spring Damper <72>
Thread
Weight Damper (B) <66>
Fan Guide <67>
Seal Lock Hex. Socket
Hd. Bolt M4 x 12 <74>
S
p
rin
g
Holder <73>
Cover Plate <64>
Weight (A) <55> Wei
g
ht
(
B
)
<57>
Thread
Leaf Spring <56>
Seal Lock Hex. Socket
Hd. Bolt M3 x 8 <58>

-8-
Fig. 8 ƔMounting the piston
Inner Cover [53] ass’y
Breathing groove of Piston [38]
Piston [38]
Striker [36]
O-ring D17 [37]
Air chamber
6. Mounting the piston
Mount the Piston [38] as shown in Fig. 8.
Apply the specified grease to the inner and outer circumferences of the Piston [38]. Also apply grease to
the inner and outer circumferences of the Piston Pin [39] and Piston Washer [40]. Mount the Piston
Washer [40] on the Piston [38] and then insert the Piston Pin [39].
Fill 20 grams of the specified grease into the cylinder of the Inner Cover [53] and then insert the Piston
[38] into the cylinder of the Inner Cover [53]. Insert the arm of the Reciprocating Bearing [47] of the
Second Shaft [41] assembly into the Piston Pin [39] so that the arm of the Reciprocating Bearing [47] is
sandwiched between the two Piston Washers [40] as shown in Fig. 9.
After inserting the arm, insert the spigot joint of the Bearing Holder [49] into the Inner Cover [53] with the
threaded portions of the Inner Cover [53] aligned with the holes of the Bearing Cover [50] and Bearing
Holder [49]. Here, orient the Bearing Holder [49] as shown in Fig. 10.
As shown in Fig. 11, one of the bolts touches the Reciprocating Bearing [47] and cannot be inserted
straight into the Inner Cover [53]. Therefore, tighten one bolt at a time, rotate the Reciprocating Bearing
[47] so that new Seal Lock Hex. Socket Hd. Bolt M5 x 16 [48] can be inserted straight in, and then fully
tighten the bolts.
After tightening the bolts, allow the Reciprocating Bearing [47] to make one rotation and confirm that the
Piston [38] makes one reciprocation. Pull the Piston [38] to confirm that it does not come off.
Pushing the Striker [36] into the Piston [38] compresses the air in the air chamber. The compressed air is
released when O-ring D17 [37] exceeds the breathing channel of the Piston [38]. Push in the Striker [36]
until O-ring D17 [37] exceeds the breathing channel of the Piston [38]. (Listen for the sound of air being
released when O-ring D17 [37] exceeds the breathing channel of the Piston [38].)

-9-
Fig. 9 ƔMounting the piston Fig. 10 ƔMounting the bearing holder
Fig. 11 ƔTightening the bolts
Piston Washer [40]
Piston [38]
Arm of Reciprocating Bearing [47]
Bearing Cover [50]
Inner Cover [53]
Bearing Holder [49]
Seal Lock Hex. Socket Hd.
Bolt M5 x 16 [48]
CAUTION: Do not tighten the bolt when
it is skewed in contact with
the reciprocating bearing.
Flat portion of Bearing Holder [49]
Inner Cover [53]

-10-
7. Reassembling the gear cover ass’y
Mount Washer (A) [25] and the Cylinder [20] assembly on the Inner Cover [53] assembly containing the
Piston [38], and then mount the Bearing Washer [18] on the front end of the Second Shaft [41].
Put the Change Plate [46] claw on the end of the Clutch [44]. Then, as shown in Fig. 12, secure the
Change Plate [46] so that the wing-like surface of the Change Plate [46] is parallel with the plane made by
the center axis of the Second Gear [23] and the center axis of the Second Shaft [41]. It is easy to secure
the Change Plate [46] in parallel with the plane by placing the Change Plate [46] in contact with the tooth
plane of the Second Gear [23] as shown in Fig.13. Determine the position of the Gear Cover [7] so that
the wing-like portion of the Change Plate [46] may be inserted into the rail portion of the Gear Cover [7].
Lay the Gear Cover [7] over a position where you can see the front end boss of the Change Plate [46]
through the insertion hole of the Change Lever (13)<12>{12} (position indicated by Fig. 14). With the Gear
Cover [7] in that state, use a pair of tweezers or other means to reposition the Change Plate [46] so that
the front end boss of the Change Plate [46] is inserted into Spring (E) [16] (or the center axis of the
Change Plate [46] may be parallel with the center axis of the Second Shaft [41]). Further lay the Gear
Cover [7] in position, confirm that the front end boss of Change Plate [46] is inserted into Spring (E) [16],
and then continue laying it into position until it contacts the Housing (65)<65>{75}.
ƔSecuring the change plate
ƔReassembling the gear cover ass’y
Bearing Washer [18] Washer (A) [25]
Parallel
Fig. 12 Fig. 13
Fig. 14
Clutch [44] end
Change Plate [46] claw
Clutch [44] end
Wing-like
surface
Wing-like surface
Change Plate [46] claw
Center axis of
Second Gear [23]
Center axis of
Second Shaft [41]
Gear Cover [7] rail
Wing-like portion of
Change Plate [46]
Contact
Contact
Spring (E) [16]
Front end boss of
Change Plate [46]
Change lever insertion hole

-11-
Fig. 15 ƔInserting the change lever
Center hole of Change Plate [46] Change Lever (13)<12>{12} pin
Pushing Button [11] pin
8. Mounting the change lever
Orient the Pushing Button [11] to position its pin at the position shown in Fig. 15 while strongly pressing
the Pushing Button [11] into the hole on the Change Lever (13)<12>{12}, and then insert the Change
Lever (13)<12>{12} into the Gear Cover [7] assembly so that the pin of the Change Lever (13)<12>{12} is
inserted into the center hole of the Change Plate [46]. Reverse the Change Lever (13)<12>{12}
disassembly procedure and set the Change Lever (13)<12>{12} to "Rotation + Hammering" ( mark) or
"Rotation only" ( mark).
9. Operation check
If an improperly assembled product is powered on, components of the running motor may be damaged.
To prevent this, you must first check the operation of the assembled product by following the procedure
below.
(1) After reassembly, turn the Change Lever (13)<12>{12} from "Rotation + Hammering" ( mark) to
"Rotation only" ( mark) and confirm that it is switched normally.
(2) Set the Change Lever (13)<12>{12} to the "Rotation + Hammering" ( mark) position, insert the
SDS plus shank into the Cylinder [20], let the cylinder make one rotation, and then confirm that the fan
rotates.
(3) Set the Change Lever (13)<12>{12} to the "Rotation only" ( mark) position, insert the SDS plus
shank into the Cylinder [20], let the cylinder make one rotation, and then confirm that the fan rotates.


-12-
Fig. 16 ●Specified grease (for rotary hammer)
●Periphery of the Second Hammer [30] (Fig. 17), O-ring (C) [33], and Damper (A) [32]: Apply specified
grease.
●Second Gear [23] and Cylinder Clutch [22] claws: Apply specified grease. (Fig. 18)
●Pin D2.5 [21]: Apply NIPPECO SEP-3A grease.
●Inner circumference of the Cylinder [20] (sliding portion of the piston): Apply specified grease. (Fig. 19)
●Balls of the Reciprocating Bearing [47]: Fill 3 grams of specified grease. (Fig. 20)
●Bore surface and arm of the Reciprocating Bearing [47]: Apply specified grease. (Fig. 20)
●Reciprocating Bearing [47] rotating shaft and Second Shaft [41] spline: Apply specified grease. (Fig. 21)
●Clutch [44], Washer [45], and Change Plate [46] contact: Apply specified grease. (Fig. 22)
●Tooth plane of the First Gear [51]: Apply NIPPECO SEP-3A grease.
●First Gear [51] recess of the Inner Cover [53]: Fill 3 grams of NIPPECO SEP-3A grease. (Fig. 25)
●Metal inner circumference of the Inner Cover [53]: Apply specified grease. (Fig. 25)
●Inner circumference of the Piston [38], inner circumference of the Piston Pin [39], and Piston Washer
[40]: Apply specified grease. (Fig. 23)
●Periphery of the Striker [36] and O-ring D17 [37] for the Striker [36]: Apply specified grease. (Fig. 24)
●Run-off of Ball Bearing 608VVC2PS2L [17] on abutted surface of the Gear Cover [7]: Fill 0.3 gram of
NIPPECO SEP-3A grease. (Fig. 26)
●Oil Seal [9] lip in the Gear Cover [7]: Apply specified grease.
●Washer (A) [25]: Apply specified grease.
●Inside of the Gear Cover [7]: Fill 40 grams of specified grease (grease for rotary hammer). (Fig. 27)
(Apply grease to the tooth plane of Second Gear [23]. Be careful not to let grease run into Cylinder
[20].)
●Inside of the Inner Cover [53] cylinder: Fill 20 grams of specified grease. (Fig. 25)
●Gear Cover [7] Φ20 bore surface and O-ring (S-18) [14] for the Change Lever (13)<12>{12}: Apply
NIPPECO SEP-3A grease.
●Steel Ball D7.0 [19]: Apply NIPPECO SEP-3A grease.
CAUTION: The viscosity and consistency of this specified grease are optimized for the rotary
hammer models in order to improve service life. Therefore, applying the ordinary
grease used for conventional models (DH 24PB3, etc.) to the Models DH 24PG,
DH 26PB and DH 28PBY may dramatically shorten its service life.
Lubrication points and types of lubricant
Service code
500 g: 335781
60 g: 335782
500 g 60 g

-13-
Fig. 17 Fig. 18
Fig. 19 Fig. 20
Fig. 21 Fig. 22
Fig. 23
* Apply or fill with the specified grease unless otherwise specified.
Second Hammer [30]
Apply to the entire periphery.
Apply to the claws.
Second Gear [23]
Cylinder Clutch [22]
Cylinder [20]
Apply to the bore surface
(sliding portion of the piston).
Reciprocating Bearing [47]
Fill 3 grams in the ball portion.
Apply to the arm.
Apply to the bore surface
Second Shaft [41]
Apply to the rotating shaft of the
Reciprocating Bearing [47].
Apply to the spline.
Washer [45] Clutch [44]
Change Plate [46]
Apply to the sliding portion.
Piston [38] Piston Washer [40]
Piston Pin [39]
Apply to the inner surface.
Apply to the outer surface.
Apply to both surfaces.
Apply to the inner surface.
Apply to the outer surface.
Apply to the inner surface.

-14-
Fig. 24 Fig. 25
Fig. 26 Fig. 27
Striker [36]
Fill 20 g of grease
inside the cylinder.
Fill 3 g of SEP-3A in the
recess of the First Gear [51].
Apply to the inner surface of metal.
Fill 0.3 g of SEP-3A in the run-off on the abutted
surface of Ball Bearing 608VVC2PS2L [17].
Gear Cover [7] Gear Cover [7]
Fill 40 g of grease inside the Gear Cover [7].
Apply to the outer surface.
Inner Cover [53]

-15-
ƔHex. Hd. Tapping Screw D4 (61)<61>{68} ······································ 1.96 ± 0.49 N•m (20 ± 5 kgf•cm)
ƔTapping Screw (W/Flange) D4 x 16 (77)<74>{84}····························· 1.96 ± 0.49 N•m (20 ± 5 kgf•cm)
ƔTapping Screw (W/Flange) D4 x 20 (Black) (82)<82>{92}··················· 1.96 ± 0.49 N•m (20 ± 5 kgf•cm)
ƔTapping Screw (W/Flange) D5 x 35 (66)<66>{76}····························· 2.94 ± 0.49 N•m (30 ± 5 kgf•cm)
ƔSeal Lock Hex. Socket Hd. Bolt M3 x 8 <58>··································· 2.45 ± 0.50 N•m (25 ± 5 kgf•cm)
ƔSeal Lock Hex. Socket Hd. Bolt M4 x 12 <74> ································· 3.43 ± 0.50 N•m (35 ± 5 kgf•cm)
ƔSeal Lock Hex. Socket Hd. Bolt M5 x 16 [48] ································· 5.88 ± 1.47 N•m (60 ± 15 kgf•cm)
Upon the completion of disassembly and repair, measure the insulation resistance and dielectric strength.
Insulation resistance: 7 Mȍor higher (as measured with a 500 VDC megohm tester)
Dielectric strength: 2500 VAC per minute, with no abnormalities
After no-load operation for 30 minutes, the no-load current values should be as follows:
Voltage (V) 110 120 127 220 230 240
Current (A) max. 3.0 2.8 2.6 1.6 1.5 1.4
Insulation test
Screw ti
g
htenin
g
tor
q
ue
No-load current value

-16-
Connecting diagram
Fig. 28 ƔWiring diagram for the Models DH 24PG, DH 26PB and DH 28PBY without noise suppressor
Fig. 29 ƔWiring diagram for the Model DH 24PG equipped with a noise suppressor
Black or brown
Gray White
Brown
Blue
BlackRed
White or blue
Cord
Stator
Stator
(Speed control switch)
Switch
(Reversing switch)
Switch
Black or brown
Gray White
Brown
Blue
BlackRed
White or blue
Cord
Stator
Stator
Noise
Suppressor (78)
(Speed control switch)
Switch
(Reversing switch)
Switch
CR unit
Choke Coil (79)
Choke Coil (80)

-17-
Fig. 31 ƔWiring diagram for the Models DH 26PB and DH 28PBY without CR unit but equipped with a noise suppressor
Fig. 30 ƔWiring diagram for the Models DH 26PB and DH 28PBY equipped with a noise suppressor and CR units
Black or brown
Gray White
Brown
Blue
BlackRed
White or blue
Cord
Stator
Stator
Noise
Suppressor
<76>{86}
(Speed control switch)
Switch
(Reversing switch)
Switch
CR unit
Choke Coil <77>{87}
Choke Coil <78>{88}
CR unit
Black or brown
Gray White
Brown
Blue
BlackRed
White or blue
Cord
Stator
Stator
Noise
Suppressor
<76>{86}
(Speed control switch)
Switch
(Reversing switch)
Switch
Choke Coil <77>{87}
Choke Coil <78>{88}

-18-
(1) Wiring of the forward/reverse changeover switch
As shown in Fig. 32, connect Internal Wire
(A) Blue (74)<71>{81} to (1) (number
stamped on the forward/reverse
changeover switch) and Internal Wire (A)
Brown (73)<72>{82} to (2). Connect a white
internal wire to (3) and a black internal wire
coming from the Stator (62)<62>{69} to (4).
Lightly pull on each connected wire to
confirm that it does not easily come out.
You can pull out each internal wire by
inserting the tip of a small flat-blade
screwdriver or needle into a window
provided on the side of each terminal.
(2) Wiring of the variable-speed switch
As shown in Fig. 33, connect the black Cord
(67)<67>{77} to 1Ĺ(number stamped on
the variable-speed switch) and the white
Cord (67)<67>{77} to 2Ĺ. Tighten each
terminal screw (with tightening torque of 0.6
± 0.2 N•m (6 ± 2 kg•cm)). Connect the gray
internal wire coming from the Stator
(62)<62>{69} to M1 and the red internal
wire coming from the Stator (62)<62>{69}
to M2. Connect the internal wires coming
from the Noise Suppressor (78)<76>{86} to
C1 and C2, respectively.
Lightly pull on each of the connected cords
and internal wires to confirm that the
cords/wires do not easily come out.
You can pull out each internal wire by
inserting the tip of a small flat-blade
screwdriver or needle into a window
provided on the side of each terminal.
Switch-related wiring
Fig. 32 ƔWiring of the forward/reverse changeover switch
Internal Wire (A) Blue
(74)<71>{81} or Choke Coil
(A) Blue (80)<78>{88}
Stator (62)<62>{69}:
White
Stator
(62)<62>{69}: Red
Fig. 33 ƔWiring of the variable-speed switch
Cord (67)<67>{77}:
White
Cord (67)<67>{77}:
Black
Internal Wire (A) Brown
(73)<72>{82} or Choke Coil
(A) Brown (79)<77>{87}
Stator (62)<62>{69}:
Black
Stator
(62)<62>{69}: Gray
Noise Suppressor
(78)<76>{86}

-19-
MODEL Variable
Fixed 10 20 30 40 50 60 min.
DH 24PG
DH26PB
DH 28PBY
General Assembly
Switch
Cord
Striker
O-ring D17
Piston
Piston Pin
Piston
Washer x 2
O-ring D72.2
Armature
Ball Bearing
(608VVC2)
O-ring (P-22)
Ball Bearing
(608DDC2)
Inner Cover
Ball Bearing
(608VVC2)
x 2
Second
Shaft
Clutch
Spring
Clutch
Change
Plate
Reciprocating
Bearing
Bearing
Holder
Bearing
Cover
First Gear
Weight
Damper (A)
(DH 28PBY)
Weight (A)
(DH 28PBY)
Leaf Spring
(DH 28PBY)
Weight (B)
(DH 28PBY)
Spring
Damper x 2
(DH 28PBY)
Spring
Holder
(DH 28PBY)
Housing
Stator
Second
Hammer
Oil Seal (A)
Hammer
Holder (C)
Sleeve (FW)
Hammer
Holder (A)
Damper (A)
O-ring (C)
Damper
Holder
Gear Cover
Oil Seal
Ball Bearing
(6805DD)
Cylinder
Cylinder
Clutch
Second Gear
Spring (A)
Work Flow
Handle
Cover
Cord Armor
Front Cap
Grip
Ball Holder
Holder
Spring
Steel Ball
D7.0
Change
Lever
Pushing
Button
O-ring (S-18)
STANDARD REPAIR TIME (UNIT) SCHEDULES