SUB-SECTION 4D
CONTROL VALVES
TABLE 4D-7
TROUBLE, CAUSE AND REMEDY CHART (CONTINUED)
REMEDY
TROUBLE
PROBABLE CAUSE
Clean and tighten.
Loose seal plates.
Replace seals.
Cut or scored seal.
Dirt in valve.
Clean and flush out valve.
Unable to move plunger in or out.
Replace seaIs.
Plunger cap full of oil.
Free up linkage.
Binding linkage.
Remove, clean install & reset.
Port relief valve not holding.
Load will not hold.
Remove, clean and re-install.
Contamination holding load
holding check open.
Replace valve section.
Oil by-passing valve plunger.
Check linkage.
Spool not centered.
Remove and clean.
Dirt in load holding check.
Load drops when plunger is
moved from neutral.
Replace poppet or plunger as necessary.
Scored check valve, poppet or seat.
Torque to proper valve.
Valve leaks between sections.
Valve not torqued to properly.
Disassemble valve and replace necessary
O-ring damaged.
O-rings.
Clean valve section surfaces.
Contamination between sections.
draulic system, have the greatest potential for causing
Figure 4D-15 is an exploded view of the valve showing the
damage. This is because such contaminants are carried
proper relationship of the parts for reassembly. Refer to
under high pressure to the working portion of the
this figure while disassembling and reassembling the valve,
system before being removed from the oil by the
unless otherwise specified.
return line filter.
DISASSEMBLY. The following disassembly procedure
1. Loosen nuts (1) on the ends of the through-bolts, in
assumes that the complete valve will be disassembled. The
small increments, initially. Then remove all attaching nuts.
following instructions have been arranged to provide the
best method of completely disassembling and reassembling
2. When the nuts are removed from all through-bolts, care-
the telescope control valve. The instructions for disas-
fully slide the inlet section off the through-bolts. Note the
sembling and reassembling a subassembly, such as the inlet
number and location of the O-rings on the inlet section. If
section, are given in the Iettered stops following the removal
the inlet section of the valve must be disassembled, proceed
of the subassembly. In the event that it is not necessary to
as follows:
overhaul a subassembly, proceed to the next numbered
A. Remove plugs (5), and carefully push the compen-
step.
sator spool out of inlet body (3).
To disassemble the telescope control valve, proceed as fol-
B. Remove plug (13), spring (11) and ball (10) from
lows:
inlet body (3). Orifice (9) should not be removed
NOTE
unless it is plugged. If the orifice is plugged, it can be
Disassembly should only be attempted on a bench in
removed using a suitable Allen wrench.
as clean an area as possible. The workbench, the
C. Remove relief valve assembly (6) from inlet body (3).
mechanic's hands and tools must be clean, and the
The relief valve assembly should not be disassembled
disassembled valve must be protected from airborne
unless it requires cleaning, in which case the puts can
dust. Contaminants introduced directly into the
be unscrewed to separate them.
control valve, or any other components of the hy-
4D-21