Reference Material; Lubrication; Tool Structure - Hitachi DH 24PM Technical And Service Manual

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8. REFERENCE MATERIAL

It is not necessary to replenish the grease lubricant unless the tool is disassembled or there is grease leakage

due to a defective seal. Special grease is used in the striking section. Should the striking section (within the gear

cover) be disassembled, carefully remove the old grease from all parts and, on reassembly, inject 45 g (1.6 oz) of

new grease into the gear cover and 5 g (0.2 oz) into the groove of the inner cover. Be careful not to exceed the

designated amount of grease. Excessive grease will reduce striking efficiency. Apply Molub Alloy No. 777-1

grease to the pin portion of the change lever.

Transmission of rotation

Unlike conventional hammer drills, the armature shaft in the Model DH 24PM is in parallel with the tool shaft -

the same structure that is employed in most impact drills. This structure was adopted in order to make the

Model DH 24PM more compact for easier handling and operation. Thus, the appearance of the Model

DH 24PM is similar to that of an impact drill. The rotation of the armature is transmitted to the second shaft via

the first gear, and causes it to rotate. The second pinion provided on the second shaft engages the second

gear mounted on the outer circumference of the cylinder. The cylinder is coupled to the second gear by

means of a slip mechanism, and they rotate together. The tip of the cylinder is fit in the bit holder. It is coupled

to the drill bit inserted in the bit holder by means of two key rails and one steel ball to transmit rotation.

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