Hitachi DH 18DPA Service Manual page 4

3. Disassembly of the cylinder assembly
(1) Disassembly of the slip clutch ass'y
Remove the Machine Screw M4 x 5 [14]{14} that fixes the Change Lever [11]{11} and Stopper [13]{13}
in the Gear Cover [9]{9}. Pull out the Change Lever [11]{11} and Stopper [13]{13} from the Gear Cover
[9]{9}. Push the tip of the Cylinder [20]{20} to remove it from the Gear Cover [9]{9}. Use the retaining
ring puller to pull out the Retaining Ring for D25 Shaft [15]{15} from the Cylinder [20]{20}. Then remove
the Second Gear [18]{18}, Spring (A) [17]{17}, and Washer [16]{16} from the Cylinder [20]{20}.
(2) Removal of the parts from the inside of the cylinder
NOTE: Use the special repair tools specified in the
table for removal of the parts from the
inside of the Cylinder [20]{20}.
Insert the J-407 stopper ring jig into the Cylinder
[20]{20} as shown in Fig. 4 until it contacts the end of
the Hammer Holder [24]{24}.
Clamp the ends of the Cylinder [20]{20} and J-407 stopper ring jig with a vise to compress the O-ring
[23]{23}. Insert the J-341 punch (C) into the two 4-mm dia. hole (2 places) on the Cylinder [20]{20} and
hammer the punch head to give force to the periphery of the Stopper Ring [25]{25} in order to detach
the Stopper Ring [25]{25} from the bore groove of the Cylinder [20]{20}. At this time, fully hammer along
the periphery of the Stopper Ring [25]{25} until the Stopper Ring [25]{25} disappears from the two 4-
mm dia. holes. Then unclamp the Cylinder [20]{20} from the vise and use J-341 ring puller jig (B) to pull
out the Stopper Ring [25]{25} from the inner circumference of the Cylinder [20]{20}.
NOTE: • Be careful not to let the Stopper Ring [25]{25} pop out. Once the Stopper Ring [25]{25}
is detached from the Cylinder [20]{20}, the Hammer Holder [24]{24}, O-ring [23]{23}, and
Second Hammer [22]{22} can be removed from the Cylinder [20]{20}.
• Do not reuse the removed Stopper Ring [25]{25} and O-ring (C) [23]{23} as they are
deformed at disassembly. Be sure to use the new Stopper Ring [25]{25} and O-ring (C)
[23]{23} at reassembly.
Fig. 4 • Removal of the parts from the inside of the cylinder
J-407 stopper ring jig
Vise
J-407
J-341
Hammer
J-341 punch (C)
4-mm dia. hole
[25]{25}
[24]{24}
4-mm dia. hole
-3-
Special repair tool
Stopper ring jig
Ring puller jig (B)
Punch (C)
[23]{23}
[22]{22}
Vise
[20]{20}
Code No.
376747
324203
324204