Swing Circuit Control Valves
STICKING PLUNGERS
CAUSE REMEDY
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
Linkage binding Free up linkage
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
CAUSE REMEDY
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
UNABLE TO MOVE PLUNGER IN OR OUT
CAUSE REMEDY
Water frozen in plunger caps Remove caps to clean out
Dirt in valve Clean and flush out
Plunger cap full of oil Replace seals
Bind in linkage Free up linkage
LOAD DROPS WHEN PLUNGER MOVED FROM NEUTRAL
CAUSE REMEDY
Dirt in check valve Disassemble and clean
Scored check valve poppet or seat Replace poppet or lap poppet to seat
T300-1_T500-1_T780
Troubleshooting
414 P/N 12261-683
REVISED: January 2015
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