References; Grease Replacement Procedures; O-Ring Replacement - Hitachi DH 50MB Technical Data And Service Manual

8. REFERENCES

8-1. Grease Replacement Procedures

The electro-pneumatic hammering section and gear change section each use different kinds of grease.
It is not necessary to replenish the grease unless the tool is disassembled for repair or there is a grease leakage
due to a damaged seal.
A special grease is used for the hammering section. To change the grease in the hammering section (Cylinder
Case and Crank Case), carefully wipe the old grease off the parts, and re-lube with 30 g in the Cylinder Case and
75 g in the Crank Case (on the Connecting Rod side). Take care not to overfill with grease as an excessive
amount of grease can cause hammering failure.
The gear change section (in the Gear Cover) uses grease No. 29 for power tools. Lube with 40 g of this grease.
Do not use the special grease used for the hammering section, or it will leak to the motor parts resulting in failure
of the tool.

8-2. O-Ring Replacement

The O-ring (attached to the Striker and Piston) plays an important role to ensure air tightness. Despite its
prolonged service life due to its special rubber material, it will inevitably wear out. Early replacement, preferably
once every six months, is recommended.
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