National Crane 600H, Руководство по обслуживанию

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2
NATIONAL CRANE
08-19-2022 Control # 092-13
2-9
600H SERVICE MANUAL HYDRAULIC SYSTEM
SERVICING THE CONTROL VALVES
Disassembly and Reassembly of Control
Valves to Replace Seals
NOTE: For clarification, the inlet cover containing the main
relief is called the left side of the main control valve
assembly.
1. Before disassembly, numerically mark each valve for
correct reassembly.
2. Remove three stud nuts from the end section.
3. Remove valve sections by sliding from assembly studs.
4. If valve sections are to be added or removed, use the
proper length stud.
NOTE: Use assembly nuts, three required, with all
assembly studs. No lockwashers! All studs are
stress-proof material and should be replaced only
with original equipment replacement parts.
5. Thoroughly clean o-ring counterbores and ground
surfaces of each section.
6. Replace the four o-rings for crane valve, the three
o-rings for the hoist valve, and seals. There are two
seals per section. Buna-N seals are standard.
7. Replace the valve sections on assembly studs in the
same order in which they were removed.
NOTE: Use care in replacing valve sections to avoid
dislodging o-rings from counterbores.
8. When all valve sections are positioned on assembly
studs, replace stud nuts and tighten evenly to 32 ft-lb
(43 N.m) torque for crane valve and 25 ft-lb (34 N.m)
torque for hoist valve.
NOTE: If stud nuts are not tightened to the proper torque,
valve spools may bind or stick, or cause section
seals to extrude.
Replacing Spool Seals
Valve sections and covers are identified by numbers cast into
the body.
1. Remove bonnet assembly parts from back of valves and
keep in order of disassembly.
2. Remove all parts connected to the spool on the front of
the valve.
NOTE: Do not remove the spool because the seals can be
replaced externally. To prevent the spool from
turning, insert a screw driver through clevis slot. Do
not hold the spool with a wrench. This will destroy
the finish.
3. Remove retainer plate, retainer plate washers, back-up
washers, and spool seals.
4. Thoroughly clean counterbore.
5. Lightly oil new seals. Slide over valve spool and insert in
seal counterbore.
REFERENCE ONLY