Idling-Proof Mechanism; Shock-Absorbing Mechanism - Hitachi H 45SR Technical Data And Service Manual

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8-2. Idling-Proof Mechanism

When the bull point is released from the concrete surface, sleeve (A) and the second hammer are forcibly moved

to the position illustrated in Fig. 5 by spring (C), and the striker moves out of striking position. When this occurs,

the air holes located at the position unaffected by the rebound of the striker at no load are opened and the

pressure within the air chamber remains unchanged even though the piston continues to reciprocate, thereby

preventing striking operation.

At the instance of releasing the bull point from the concrete by moving the main body up, the second hammer

contacts hammer holder (A) as shown in Fig. 6 then the cushion (damper (A)) provided between hammer holder

(A) and the front cover absorbs the striking force of the second hammer. Thus the durability of the Model H 45SR

is increased greatly because the second hammer does not strike the tool retainer directly.

Second hammer

Forward movement of

second hammer & striker

Fig. 5

Hammer holder (A)

Fig. 6

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Striker

Damper (A)

Sleeve (A)

Spring (C)

Air

chamber

Air hole

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