4-19
Published 9-04-2014, Control # 422-08
RT765E-2 SERVICE MANUAL
BOOM
4
GROVE
3.
Telescope
cylinder will not
extend.
a.
Low hydraulic oil level.
a.
Check system for leaks. Make repairs as
needed. Fill reservoir.
b.
Relief valve malfunctioning.
b.
Repair or replace relief valve.
c.
Excessive load.
c.
Reduce load.
d.
Clogged hose and fittings.
d.
Replace hose or fittings. (Refer to
Manitowoc Crane Care Parts Manual).
e.
Broken valve spool.
e.
Replace valve.
f.
Damaged piston seals.
f.
Replace all cylinder seals.
g.
Damaged piston(s).
g.
Replace piston(s) and all cylinder seals.
h.
Bent boom section(s).
h.
Replace damaged boom section(s).
i.
Broken hydraulic pump coupling.
i.
Replace broken hydraulic pump coupling.
j.
Worn or damaged hydraulic pump
section.
j.
Repair or replace pump section.
4.
Telescope
cylinder will not
retract.
a.
Low hydraulic oil level.
a.
Check system for leaks. Make repairs as
needed. Fill reservoir.
b.
Relief valve damaged.
b.
Repair or replace relief valve.
c.
Excessive load.
c.
Reduce load. (Refer to load chart).
d.
Inoperative check valve.
d.
Replace check valve.
e.
Clogged hose and fittings.
e.
Replace hose or fittings. (Refer to
Manitowoc Crane Care Parts Manual).
f.
Broken valve spool.
f.
Replace valve section.
g.
Broken piston(s).
g.
Replace piston(s) and all cylinder seals.
h.
Damaged piston seals.
h.
Replace all cylinder seals.
i.
Bent boom section(s).
i.
Replace damaged boom section(s).
j.
Broken hydraulic pump coupling.
j.
Replace broken hydraulic pump coupling.
k.
Worn or damaged hydraulic pump.
k.
Repair or replace pump.
l.
Broken hydraulic pump shaft.
l.
Replace pump shaft.
5.
Inner mid will not
extend.
a.
Right side check valve blocked.
a.
Readjust, repair, or replace valve.
6.
Inner mid will not
retract.
a.
Right side check valve closed.
a.
Readjust valve.
7.
Outer mid will
not extend.
a.
Left side check valve is closed.
a.
Readjust valve.
8.
Inner mid
retracts before
outer mid.
a.
Right side check valve is open or
hosed backwards.
a.
Install hoses properly.
9.
Outer mid
extends only a
short distance
then stops.
a.
Left check valve is open or hosed
backwards.
a.
Install hoses properly.
SYMPTOM
PROBABLE CAUSE
SOLUTION
Reference Only