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