Manitowoc Grove RT770E Service Maintenance Manual page 229

RT770E
Symptom
5. Swing operation
slow in one
direction only.
6. Swing brake
operation erratic.
7. Swing brake
system will not
operate.
8. Swing brake pedal
is spongy.
9. Swing brake drags.
10. Boom swings
slowly.
11. Swing motor
continues to
operate when
swing control is in
neutral.
GROVE
Probable Cause
a. Crane not level.
b. Damaged hydraulic remote control
valve.
c. Damaged swing directional control
valve.
d. Clogged or restricted hose.
e. Improperly torqued turntable bearing.
a. Improper brake adjustment.
b. Air in swing brake system.
c. Brake pedal not fully retracted.
d. Dirty or glazed brake disc.
e. Malfunction of the glide swing power
brake valve.
f. Kinked or bent lines and/or hoses and
fittings.
a. Damaged swing brake release valve.
b. Damaged glide swing power brake
valve.
c. Internal damage to the swing brake
assembly.
d. Loose or restricted brake lines or
fittings.
a. Damaged glide swing power brake
valve.
b. Loose or restricted brake lines or
fittings.
a. Damaged glide swing power brake
valve.
b. Damaged swing brake release valve.
c. Internal damage to the swing brake
assembly.
d. Loose or restricted brake lines or
fittings.
a. Insufficient hydraulic volume.
b. Damaged relief valve.
c. Damaged swing motor.
a. Hydraulic remote control valve sticking
or valve otherwise damaged.
b. Control valve sticking
otherwise damaged.
Published 11/26/2014, Control # 447-05
a. Level crane.
b. Replace
valve.
c. Replace the swing directional control
valve.
d. Replace hose or fitting.
e. Torque turntable bearing.
a. Adjust brake.
b. Bleed brake system.
c. Check brake pedal return spring; repair
or replace spring.
d. Clean or replace disc.
e. Repair or replace glide swing power
brake valve.
f. Straighten or replace as required.
a. Replace release valve.
b. Repair or replace glide swing power
brake valve.
c. Repair or replace affected parts.
d. Tighten or replace lines and fittings.
a. Repair or replace the glide swing
power brake valve.
b. Tighten or replace brake lines and
fittings.
a. Repair or replace the glide swing
power brake valve.
b. Replace release valve.
c. Repair or replace affected parts.
d. Tighten or replace brake lines and
fittings.
a. Check delivery of hydraulic pump.
Ensure sufficient fluid is available to
pump. Check pump drive speed.
b. Adjust, repair, or replace valve.
c. Repair or replace motor.
a. Repair or replace valve.
or valve b. Repair or replace valve.
SWING SYSTEM
Solution
hydraulic remote control
6-5
6