Hitachi DH 40SR Service Manual And Technical Data page 27

(6) Carbon brush inspection
The motor employs Carbon Brushes [91] which are
consumable parts. When they become worn to or
near "wear limit" (7 mm), it could result in motor
trouble. Replace the Carbon Brushes [91] with new
ones which are numbered "73" as shown in Fig. 22.
In addition, always keep Carbon Brushes [91] clean
and ensure that they slide freely within the brush
holders.
(7) Application of lubricant
Apply special grease (for hammer and rotary hammer) to the inner circumference of the Connecting Rod [41],
the O-rings [37] of the Striker [36] and the Piston [39], the sliding portion of the Second Hammer [23], O-ring
(C) [22] of the Second Hammer [23], the Damper [25], the inner and outer circumference of Bevel Gear [42],
inner circumference of Slide Sleeve (A) [33], inner circumference of Slide Sleeve (B) [32], inner circumference
of Sleeve (A) [35], the Slide Ring [29], Damper (C) [28], Damper Holder (B) [27], Oil Seal (A) [60], Oil Seal (B)
[14] and Oil Seal (B) [55]. Fill 50 g of the special grease in the Cylinder Crank Case [56] on the Connecting
Rod [41] side and 20 g in the Cylinder Crank Case [56] on the Clutch [38] side. Apply Hitachi Motor Grease
No. 29 to the Needle Bearing (M661) [73] and the pinon portion of the Armature Ass'y [82]. Fill 30 g of the
Hitachi Motor Grease No. 29 in the Cylinder Crank Case [56] on the First Gear [72] side and the Gear Cover
[74] side. Apply Doubrex 251 grease to the outside diameter portion, hexagonal hole and claws of the Driver
[13] and Damper (B) [11]. Fill 8 g of Doubrex 251 grease in Front Cover (A) [9].
(8) Oil seal and others
Take care not to scratch or cut Oil Seal (A) [60], Oil Seal (B) [14] and Oil Seal (B) [55] of Cylinder Crank Case
[56], O-ring (1AS-60) [10] of Front Cover (A) [9], O-ring (C) [22] of Second Hammer [23], Rubber Seal [48] of
Crank Cover [46] and O-ring [37] of Piston [39] and Striker [36].
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Wear limit
No. of carbon brush
("73" means the last
two digits of the code
number.)
Fig. 22