Reference Materials - Hitachi DH 28PC Technical Data And Service Manual

REFERENCE MATERIALS

1. Grease replacement procedures
The hammering section and gear change section use different types of grease. Grease need not be
replenished unless the tool is disassembled for repair or grease is leaking due to a damaged seal.
A special grease is used for the hammering section. After disassembling the hammering section (inside the
cylinder case and crank case), carefully wipe old grease off the parts and fill the crank case (on the
connecting rod side) with 25 g of grease and the crank case (on the cylinder side) with 5 g. Be careful not to
overfill with an excessive amount of grease, which could cause hammering failure.
The gear change section (inside the gear cover) uses Hitachi Motor Grease No. 29. The proper amount of
grease is 15 g. Never use the special grease for the hammering section in the gear change section.
Otherwise, the special grease will leak into the motor section and cause subsequent trouble. Periodically
change the grease in the slip clutch. Fully fill the slip clutch with Cosmos Molybdenum Grease No. 2.
2. Structure of the Model DH 28PC Rotary Hammer
Steel ball Cylinder Clutch
Bevel gear
Key rail
Second gear
Bevel pinion
Armature
• Torque transmission
The rotational force of the bevel gear is transmitted to the cylinder through the clutch and rotates the
cylinder. The front side of the cylinder also serves as a drill bit holder. The drill bit inserted into the cylinder
is coupled with two key rails and one steel ball to transmit the rotation.
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