EP Equipment CQD16, Service Manual

Page: 104 / 251

90
REV. 07/2016
HYDRAULIC SYSTEM
7
Fault Symptom Failure Causes Troubleshooting Measures
1
Noisy pump
a. Insuf fi cient oil;
b. High viscosity of oil;
c. Oil suction pipe air leak;
d. Filters clogged by impurities;
e. Hydraulic oil with foam;
1. Check the hydraulic oil level.
2. Replace the hydraulic oil.
3. Check the oil suction pipe.
4. Clean the oil inlet piping,
replace the
fi lter, if necessary.
5. See Fault 2.
2
Hydraulic oil with foam
a. Pump cavitation;
b. There is water in the oil.
1. Check the amount of oil;
2. Check if the viscosity of
hydraulic oil is normal;
3. Check the oil inlet piping for air
leaks;
4. Discharge and clean, and
replace with new hydraulic oil.
3
Pump or oil
temperature is too high
a. Oil is too thin;
b. Pump cavitation;
c. Valve body internal relief.
1. Discharge and clean, and add
new hydraulic oil;
2. Check the oil inlet piping for air
leaks;
3. Replace the valve body.
4
Low System Pressure
a. Insuf fi cient oil;
b. Relief valve failure.
c. Pump wear, internal leakage.
1. Check the hydraulic oil level;
2. See Fault 6;
3. Replace the gear pump.
5 On load, declined
a. Solenoid valve failure; (RVF/
NRVF)
a. Multi-way valve failure; (RV/
NRV) 1. Check and clean the solenoid
valve spool.
1. Check the multi-way manual
valve and it installation.
6
Relief valve pressure
unstable or too low
a. Pressure adjustment screw too
loose;
b. Relief valve spring breakage or
deformation;
c. Relief valve spool wear or
blocked. 1. Adjust to proper pressure
through hydraulic pressure
gauge.
2. Replace the relief valve.
3. Clean or replace the relief
valve.
7.9 Hydraulic Troubleshooting