Hitachi NR 90GC, Технические данные и руководство по обслуживанию

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(2) Reassembly
Reassembly procedures should be followed in the reverse order. Note the following points.
Drop the Piston Bumper [40] in the Cylinder Ass'y [42] facing its stepped side inward and push it in until it
passes through the stopper portion by means of the handle of a hammer. You feel a click when the Piston
Bumper [40] passes through the stopper portion (Fig. 37).
Apply designated oil to the inside of the Cylinder Ass'y [42] and the O-ring groove on the outside of the
Cylinder Ass'y [42] according to 10-1.
Mount the two Piston Rings [38] to the Piston [39] being careful not to deform them.
Be careful of the following when mounting the Piston [39] to the Cylinder Ass'y [42] .
(1) Position each split of the two Piston Rings [38] at an angle of 90 degrees with respect to the exhaust
port aligning these two splits in 180-degree opposite positions (Fig. 38).
(2) If the Piston Ring [38] fits in the retaining ring groove inside the cylinder, insert a small flat-blade
screwdriver into the concave portion (7 places) at the end of the cylinder and lightly push the Piston [39] in
fitting the Piston Ring [38] in the groove of the Piston [39] . Do not push the Piston [39] in forcedly.
Otherwise, the Piston Ring [38] may be damaged (Fig. 39).
(3) Check that the tip of the driver blade is shown in the outlet. The Piston [39] cannot be mounted if the tip of
the driver blade contacts the Piston Bumper [40] or the bottom of the cylinder.
(4) Face the chamfered side of the tip of the driver blade in the direction opposite to the exhaust port of the
Cylinder Ass'y [42] (Fig. 39).
Cylinder Ass'y [42]
Handle of a hammer
Piston Bumper [40]
Stopper portion
Fig. 37