Daewoo D20S-2, Specifications Systems Operation Testing & Adjusting Disassembly & Assembly

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Adjustable Flow Control Valve
1. Remove the retainer ring (18) and screw out plug
stop adjuster (19) from the valve body.
2. Unscrew the adjustable relief seat (24) from the
plug stop adjuster (19).
3. Remove the back-up ring (20) and O-ring (21).
4. Remove the spring (22) and poppet (25) from the
valve body.
Relief Valve Subassembly
1. Screw out the plug (26) which retains the relief
valve and remove the O-ring (27) from the plug.
2. Remove the spring (28) and the relief valve sub-
assembly (29).
Secondary Adjustable Relief Valve
1. Screw out relief plug (30) and remove O-ring (31)
from valve body.
2. Remove setscrew (32) and nut (33) from relief
plug.
3. Remove O-ring (34) and spring (35) from relief
plug.
4. Pull piston (36) and poppet (37) from the plug.
Valve Body
1. Remove the plug (38) and O-ring (39) from
cylinder °
∞
b°± work port.
2. Remove the plug (40) and O-ring (41) on models
with a single acting spool. If the alternate discharge
port is plugged, it is not necessary to remove the
plug unless the body is to be replaced. On bodies
equipped with the quick disconnect option, remove
the dust cap (42) and the coupling (43).
3. Remove O-ring (44) from coupling.
4. Unscrew the plug (45) and remove O-ring (46).
Cleaning, Inspection And
Repair
1. Check that all internal passages are clean and free
from obstruction. Examine all mating surfaces for
nicks and burrs. Minor nicks and burrs can be
removed with a crocus cloth or an India stone.
2. Discard all old seals and O-rings. Wash all parts in
a clean mineral oil solvent and place them on a
clean surface for inspection.
NOTE : Obtain new seal kits. Refer to the appropriate
part drawing as shown on figure IDCS015B for the
seal kit part number. Apply a light film of clean
hydraulic fluid to the new seals. This will make
assembly easier and also provide initial lubrication of
moving parts.
3. Inspect the valve spools and bores for burrs and
scoring. If scoring is not deep enough to cause
objectionable leakage, the surfaces can be stoned
or polished with crocus cloth. If scoring is
excessive, the valve body and spool must be
replaced. Check the valve spool for freedom of
movement in the bore.
CAUTION : DO NOT stone the edges of spool
sealing lands. Remove minor burrs with #500 grit
paper. Use paper very lightly on the outer diameter of
each spool.
4. Check the relief valve for smooth movement in its
bore. The valve should move from its own weight.
5. Inspect all screws for evidence of damaged
threads. If threads are damaged, replace the
screws.
6. Inspect all springs for distortion or wear. The ends
of the springs shall be square and parallel to each
other. Replace springs that are damaged or
distorted.
26 of 29 New Hydraulic Systems Disassembly and Assembly