SUB-SECTION 4D
CONTROL VALVES
Figure 4D-5. Control Valve Operation (36Z726)
TABLE 4D-3
TROUBLE, CAUSE AND REMEDY CHART
REMEDY
PROBABLE CAUSE
TROUBLE
Replace O-rings.
Defective O-rings in valve body.
Oil leaks at either end of spool.
Replace springs.
Broken springs.
Spring-centered spools do not
return to neutral.
Clean system and valve.
Foreign particles.
Check linkage for binding condition.
Misalignment of operating linkage.
Repair, clean and readjust.
Relief valve not properly set, or
No motion, slow or jerky action
stuck in base and/or worn.
of hydraulic system.
Disassemble, clean and reassemble.
Dirt or foreign particles Iodged
between relief valve control pop-
pet and seat.
Check travel.
Spool not moved to full stroke.
4D-7