Hitachi DH 40MR Technical And Service Manual page 20

Switching between "Rotation + Hammering", "Neutral" and "Hammering only"
Lock sleeve
Cylinder
Change lever
Fig. 10
Clutch
Lock sleeve
Cylinder
Change lever
Fig. 11
Lock sleeve
Cylinder
Change lever
Clutch
Bevel gear
Bevel gear
Clutch
Bevel gear
Fig. 13
All the shanks of the SDS-max type working tools such as drill
bits (for drilling) and bull points (for chiseling) have the same
shape. When chiseling or chipping with the Model DH 40MR,
it is necessary to stop the rotation and choose the
"Hammering only" mode by mean of the change lever to lock
the working tool against rotation.
Figure 10 is a cross-sectional view showing the "Rotation +
Hammering" mode, in which the bevel gear claw meshes with
the clutch claw to transmit rotation to the cylinder keyed to the
clutch, so as to rotate the working tool.
Figure 11 is a cross-sectional view showing the "Neutral"
mode, in which, with the change lever turned 90˚, the bevel
gear is brought out of engagement with the clutch to cut off
transmission of rotation. In this position, the tool holder grip
can be manually turned and the working tool (for chiseling or
chipping) is adjustable to the desired position in 12 steps
easily (Fig. 12).
Figure 13 is likewise a cross-sectional view showing the
"Hammering only" mode. With the change lever turned
another 90˚, the splines on the inner circumference of the lock
sleeve come into mesh with the splines on the outer
circumference of the clutch, so that the cylinder as well as the
working tool are prevented from rotating.
Although the Model DH 40MR has three selectable modes as
mentioned above, use of a working tool for chipping or
chiseling in the "Rotation + Hammering" mode will result in an
accident. Be sure to instruct the customers to select the
"Hammering only" mode when doing chiseling or chipping
work.
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Grip
Fig. 12