Rotation Only" And "Rotation + Hammering" Changeover Mechanism; Rotation Only" (No Hammering) - Hitachi DH 22PB Technical Data And Service Manual

8-3. "Rotation Only" and "Rotation + Hammering" Changeover Mechanism

The change lever on the Model DH 22PB permits quick and easy changeover between the "Rotation Only" and
"Rotation + Hammering" functions. When operating the change lever, be sure to continue pressing the pushing
button. Armature rotation is transmitted to the second shaft and first gear, and then to the clutch via the spline on
the second shaft spline. Claws on the surface of the clutch engage matching claws on the reciprocating bearing
to convert the rotation into reciprocating motion. The clutch can travel back and forth on the second shaft. Claws
on the surface of the clutch is pressed against on the reciprocating bearing by the force of the clutch spring during
usual operation ("Rotation + Hammering"). The reciprocating bearing is fitted on the second shaft with some play.
When the change lever is set to the "Rotation Only" ( mark) position, the eccentric pin of the change lever forces
the clutch to move against the pressure of the clutch spring in the direction of the front cap, so that it disengages
from the claws on the reciprocating bearing, and the reciprocating bearing stops rotating on the second shaft.
When the change lever is returned to the "Rotation + Striking" ( mark) position, the force of the clutch spring
presses the clutch back against the reciprocating bearing so that the claws engage to transmit rotation to the
reciprocating bearing once more.

8-4. "Rotation Only" (no hammering)

The Model DH 22PB is equipped with a change lever for changeover between "Rotation + Hammering" and
"Rotation Only" functions, merely mounting the chuck adapter will not stop the hammering action; it is absolutely
necessary to turn the change lever to the "Rotation Only" setting for drilling or driving screws. Should the change
lever be set to the "Rotation + Hammering" position when the tool is used for drilling, the hammering action may
cause the drill chuck to be broken or damaged. Sales personnel should carefully ensure that the buyer is
thoroughly advised on this point.
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