Hyundai 35DS-7 Operation Manual page 165

Problem
Actuator(cylinder or motor)
works slowly or does not
operate.
Cylinder lowers considerably
under normal circumstance.
Pressure does not increase
sufficiently.
Temperature rising of the
hydraulic oil.
Steering force is heavy.
Cause
Shortage of oil in oil tank.
Decrease of relief valve pressure.
Spool got stuck.
Shortage of oil flow to the valve.
Internal leakage of cylinder happens
frequently.
Excessive leakage from spool of the
valve.
Spool got stuck.
Leakage in a part of the circuit.
Defect of relief valve.
Leakage in a part of the circuit.
Working with higher pressure than
rated pressure.
Low viscosity of oil.
Leakage from a part of the circuit.
Oil leakage in the pump.
Insufficient suction of the pump.
Defect of steering relief valve.
6-21
Remedy
Check the oil level in the oil tank.
Install pressure gauge on the circuit,
and check the pressure with it by
handling the lever.
Check that manual lever moves
smoothly.
Check that lever stroke is enough.
Check that oil flow of the pump is
within specified rate.
Fit the stop valve on the pipe
between valve and cylinder, observe
the internal leakage of cylinder.
Check the oil viscosity is not too low.
Check that manual lever moves
smoothly.
Check the circuit.
Observe leakage from pipes.
Check the relief valve.
Check the circuit.
Observe leakage from pipes.
Check the flow pressure.
Check the sort of oil and viscosity.
Check if the circuit is relieved at all
times.
Check if the temperature of pump
surface higher 30 C than oil tempera-
ture.
Check the oil tank volume.
Check if the suction strainer is
blocked.
Check the steering relief valve.