Manitowoc Grove RT770E Service Maintenance Manual page 304

UNDERCARRIAGE
Symptom
2. Sticking spool.
3. External leakage.
4. Solenoid failure.
5. Outrigger jack cylinder slow
or erratic.
8-28
Probable Cause
a. Dirt in the system.
b. Distortion caused by tie bolts
b e i n g o v e r t o r q u e d
torqued.
c. Flow in excess of valve rating.
d. Pressure in excess of valve
rating.
e. Electrical failure.
a. Damaged O-ring or quad
rings.
b. Loose tie bolts.
c. Damaged solenoid.
a. No current.
b. Damaged solenoid assembly.
c. Short in solenoid.
d. Loss of solenoid force.
a. Low in hydraulic oil.
b. Damaged main relief valve.
c. Damaged holding valve seals.
d. Bent cylinder rod.
e. Bent outrigger housing.
f. Excessive material on beams.
g. Sticking solenoid valve spool.
h. Damaged wiring to solenoid.
i. Weak brush springs
collector rings.
j. Collector ring dirty or glazed.
k. Directional selector
sticking.
l. Main hydraulic
cavitation.
m. Worn or damaged hydraulic
pump section.
Published 11/26/2014, Control # 447-05
a. Change oil and flush system.
b. Retorque tie bolts.
o v e r
c. Limit flow through valve to that
recommended. Check pump output
and cylinder ratio.
d. Check relief valve setting or pump
c o m p e n s a t i o n
recommended.
e. Check wiring and solenoids.
a. Check for chipped packings and
replace.
b. Retorque tie bolts.
c. Replace damaged parts.
a. Check power source of at least 85%
of coil rating.
b. Replace solenoid.
c. Replace coil.
d. Decrease
energization, decrease cycle rate.
a. Check system for leaks. Make
repairs as needed. Fill reservoir.
b. Repair or replace valve.
c. Replace holding valve seals.
d. Replace cylinder rod and seals.
e. Repair or replace outrigger housing.
f. Clean outrigger beams.
g. Repair or replace valve spool.
h. Repair or replace wiring.
on i. Replace brush springs.
j. Clean or deglaze collector ring.
switch k. Clean or replace switch.
pump l. Replace or tighten hose and fittings.
m. Repair or replace pump section.
RT770E
Solution
w i t h t h a t
time of solenoid