Control Valves
CONDITION CAUSE REMEDY
STICKING PLUNGERS Excessively high oil
temperature
See section on “Excessive
Heating of Oil in System”.
Dirt in oil Change oil. Clean system
Fittings too tight Check torque
Valve warped from mounting Loosen valve mounting bolts
and check
Excessively high flow in valve Check to see if hoses from
pump are not crossed or
reversed.
Plunger damaged Replace valve
Return spring damaged Replace faulty parts
Spring or detent cap binding Loosen cap, re-center and re-
tighten
Valve not at thermal
equilibrium
Let system warm up
LEAKING SEALS Paint on or under seal Remove and clean
Excessive back pressure Open or enlarge line to
reservoir
Dirt under seal Remove and clean
Scored plunger Replace valve
Loose seal plates Clean and tighten
Cut or scored seal Replace faulty parts
LOAD DROPS WHEN
CONTROL MOVED FROM
NEUTRAL
Dirt in check valve Disassemble and clean
Scored check valve poppet
or seat
Replace poppet or lap
poppet to seat
POOR HYDRAULIC SYSTEM
PERFORMANCE OR
FAILURE
Dirt in relief valve Disassemble and clean
Relief valve defective See section on “Relief
Valves”.
Load too heavy Check line pressure
Internal valve crack Replace valve
Plunger not at full stroke Check movement of spool
RT500
Troubleshooting
226 REVISED:
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