Reassembly - Hitachi DH 18DPA Service Manual

Reassembly can generally be conducted by reversing the disassembly procedure. However, special
attention should be given to the following items.
1. Reassembly of the cylinder ass'y
NOTE: Use the special repair tool specified in the
table for mounting the parts to the inside
of the Cylinder [20]{20}.
(1) Insert the new O-ring [23]{23} into the Cylinder [20]{20} as shown in Fig. 5. Then, insert the assembly
of the Hammer Holder [24]{24}, O-ring (B) [21]{21}, and Second Hammer [22]{22} into the Cylinder
[20]{20} as shown in Fig. 5.
NOTE: • Insert the Second Hammer [22]{22} into the Cylinder [20]{20} without tilting so that O-
ring (B) [21]{21} is not damaged.
(2) Push the new Stopper Ring [25]{25} into the Cylinder [20]{20} and then insert the J-407 stopper ring jig
into the Cylinder [20]{20} as shown in Fig. 5.
NOTE: • The Stopper Ring [25]{25} has a white mark to differentiate from the Stopper Ring [3]{3}.
• Push the new Stopper Ring [25]{25} into the Cylinder [20]{20} with the break of the
Stopper Ring [25]{25} facing away from the 4-mm dia. hole on the Cylinder[20]{20} as
shown in Fig. 5. If the ring break is faced toward the 4-mm dia. hole, it may be hard to
disassemble the cylinder ass'y.
(3) Use a hand press to press against the upper end of the J-407 stopper ring jig until the Stopper Ring
[25]{25} is fitted into the bore groove of the Cylinder [20]{20}.
NOTE: Check that the Stopper Ring [25]{25} is fitted securely into the bore groove of the Cylinder
[20]{20} through the two 4-mm dia. holes on the periphery of the Cylinder [20]{20}.
Fig. 5 • Reassembly of the cylinder ass'y
Break of [25]{25}
J-407 stopper ring jig
Hand press

Reassembly

J-407
4-mm dia. hole
4-mm dia. hole
4-mm dia. hole
[25]{25}
-4-
Special repair tool
Stopper ring jig
[23]{23}
Bore groove of [20]{20}
[23]{23}
[21]{21}
[22]{22}
[24]{24}
4-mm dia. hole
Code No.
376747
[20]{20}