Reference Information; Grease Replacement; O-Ring Replacement; Structure Of The Model Dh 40Mry Rotary Hammer - Hitachi DH 40MRY Technical Data And Service Manual

8. REFERENCE INFORMATION

8-1. Grease Replacement

The striking portion and the speed reduction portion of the Model DH 40MRY respectively use different types of
grease. It is not necessary to replenish the grease unless the tool is disassembled for repair or there is grease
leakage due to a damaged seal. The striking portion uses special grease. To change the grease in the striking
portion (inside the cylinder crank case), carefully wipe the old grease off the parts, and re-lube with 50 g (1.8 oz)
into the cylinder crank case (connecting rod side). Take care not to overfill the grease as an excessive amount of
grease can cause hammer failure. The speed reduction portion (inside the gear cover) uses Hitachi Motor Grease
No. 29. The proper supply volume is 30 g (1 oz). Never use the special grease for the striking portion in the speed
reduction portion. Special grease would leak into the motor portion and cause subsequent trouble. Periodically
replenish the inside of the slip clutch with Hitachi Motor Grease No. 29 to full.

8-2. O-ring Replacement

The O-rings (mounted on the striker and the piston) are extremely important to ensure adequate sealing of the air
pressure. Although the O-rings are made of special rubber to give them a long service life, they do nonetheless
become worn, and should be replaced by new ones periodically depending on frequency of use of the tool. With
average use, it is recommended that the O-rings be replaced at least every six months to ensure maximum
effectiveness.

8-3. Structure of the Model DH 40MRY Rotary Hammer

Second hammer
Grip
Needle holder
Front cap
Key rail
Retainer
sleeve
Needle pin
Needle roller
Ari chamber
Cylinder
Clutch
Striker
O-ring
Second gear
Bevel pinion
Oil seal
Armature
Fig. 3
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Bevel gear
Crank shaft
Connecting rod
Piston
Control circuit ass'y
Handle
First gear