Hitachi H 45SR, Technical Data And Service Manual

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7-4. O-Ring Replacement
The O-rings (mounted on the striker and piston) are extremely important to ensure adequate sealing of the air
pressure. Although the O-rings are made of special rubber to give them a long service life, they do nonetheless
become worn, and should be replaced by new ones periodically depending on frequency of use of the tool. With
average use, it is recommended that the O-rings be replaced at least every six months to ensure maximum
effectiveness.
8. REFERENCE INFORMATION
Structure:
Fig. 4
Connecting rod
Cylinder
Striker
Piston
Air chamber
Second hammer
O-rings
Crank cover
8-1. Striking Operation
The rotation of the armature is transferred to the crank shaft and connecting rod, which in turn cause the piston to
reciprocate inside the cylinder. As the piston reciprocates, the changing air pressure inside the air chamber
between the piston and the striker causes the striker to continuously strike against the end of the second hammer.
At the same time, the air-cushion effect within the air chamber absorbs the impact of the striker. Should the air
escape from the air chamber, the air-cushion effect would cease, and the impact energy would not be absorbed.
Accordingly, the O-rings mounted on the striker and piston play an extremely important role in sealing the air
within the air chamber.
Crank shaft
Armature