Hitachi H 45MR, Technical Data And Service Manual

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Fig. 7

O-ring

Cylinder crank case

Vibration absorbing unit

Retainer sleeve

Switch handle

Housing

O-ring

Front cover

O-ring

O-ring

Vibration
absorbing
unit

Oil seal

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.

Cylindrical rubbers (handle damper: 4 pcs.)

Slotted groove

Handle damper
retaining material
(handle side)

Cylindrical
convex

Handle damper retaining material
(Cylinder crank case and housing)

Fig. 8

Vibration-
proof rubbers Handle side

Rolled and compressed

Pressing
force of the
main body

(a) At no-load

(b) At full-load

Main body side

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