33
5. Remove the damper piston from the spool.
Th
e piston
will come out slowly, because of a partial vacuum formed
as it is removed. Use extreme care to avoid damaging the
polished surfaces of the piston or spool.
6. Remove the check valve spring retainer, spring and check
valve poppet. Check spring free length. Replace spring if
less than 1-1/2 in. (38.1 mm) long.
CLEAN AND INSPECT
1. Discard all O-rings and backup rings. Clean all parts in
solvent and blow dry. Inspect polished surfaces of spool
and damper piston for damage that may cause binding or
leakage. Inspect spool bore in valve housing for damage
or scoring. Inspect check valve seat in valve housing and
check valve poppet. If the spools, bores or valves are dam-
aged, the entire valve must be replaced as these parts are
not serviced separately.
2. Inspect the .020 inch (.5 mm) ori
fi
ce in the end of the
spool and the pilot ori
fi
ce to be certain they are open.
ASSEMBLY
1. Install new O-rings on the plug and spring retainers.
2. Install new O-rings and backup rings on the spool and
damper piston as shown. It is important that each backup
ring is on the correct side of its O-ring. Take care not
to cut the O-rings during assembly. Let the spool and
damper piston set for ten minutes before installing them
in their respective bores.
Th
is will allow the O-rings to
return to their original size a
ft
er being stretched.
3. Lubricate the spool and damper piston O-rings with hy-
draulic oil. Carefully install the damper piston into the
spool.
4. Lubricate the spool bore and spool O-rings with hydrau-
lic oil. Carefully install the spool into the valve housing.
Always install the spool from the plug end as shown to
minimize the possibility of damaging the O-ring. Install
the plug, spool spring and spring retainer.
5. Install the check valve poppet, spring and check valve
spring retainer.
6. Install the motor drain check ball, spring and elbow
fi
t-
ting.
7. Install the pilot ori
fi
ce into the valve housing.
8.
Th
e brake valve is complete and ready to be installed on
hoist motor.
