Sealed And Dustproof Construction; Vibration Absorbing Construction - Hitachi H 45MR Technical Data And Service Manual

Retainer sleeve

8-4. Sealed and Dustproof Construction

The cylinder crank case is sealed by four O-rings and an oil seal which serve to prevent leakage of the grease, as
well as to prevent dust and dirt from entering the mechanism.

8-5. Vibration Absorbing Construction

Hitachi original, innovative units which absorb vibration are installed between the switch handle and the cylinder
crank case and between the switch handle and the housing. As a result, the amount of vibration transmitted from
the main body to the arms of the operator is considerably less in comparison with conventional hammers.
Construction of vibration absorbing unit:
The main body (cylinder crank case and
housing) and the handle are connected through
four cylindrical rubbers (handle dampers).
Vibration is absorbed by the rolling and
compression of the four rubbers on inclined
surfaces. Because the vibration absorbing unit
has non-linear spring characteristics, its spring
constant factor is lower than that of the
conventional shearing rubber type vibration-
absorbing construction, and it provides
significantly higher efficiency in minimizing
vibration. In addition, the interlocking slotted
groove and cylindrical convex portions at the
center prevent the handle from being
disconnected by twisting or pulling, a common
problem with conventional hammers.
O-ring Cylinder crank case
O-ring
O-ring
Front cover
Housing
Fig. 7
Cylindrical rubbers (handle damper: 4 pcs.)
Slotted groove
Handle damper retaining material
(Cylinder crank case and housing)
Vibration-
proof rubbers Handle side
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Vibration absorbing unit
O-ring
Main body side Reaction
(a) At no-load
Fig. 8
Switch handle
Oil seal
Vibration
absorbing
unit
Handle damper
retaining material
(handle side)
Cylindrical
convex
Rolled and compressed
Pressing
force of the
main body
(b) At full-load