Reference Information; Grease Replacement; O-Ring Replacement - Hitachi DH 40SR Service Manual And Technical Data

8. REFERENCE INFORMATION

8-1. Grease Replacement

The striking portion and the speed reduction portion of the Model DH 40SR 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 striking portion special grease 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 the full.
The tool retainer portion (inside the front cover) uses Doubrex 251 grease. The proper supply volume is 8 g.

8-2. O-Ring Replacement

The O-rings (mounted on the striker and 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.
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