Manitowoc Grove RT770E, Service Maintenance Manual

Page: 284 / 357

UNDERCARRIAGE RT770E
8-8 Published 11/26/2014, Control # 447-05
Maintenance
Front Steering System
Troubleshooting
Table 8-1
Functional Check
A normal periodic functional check of the entire steering
system will generally be adequate to ensure satisfactory
service.
1. Check all fittings for leakage. An accumulation of moist,
black dirt is a good indication of leakage.
2. With the engine running at idle and at full throttle, and
with the machine standing still and moving, turn the
steering wheel through the full range of travel. Note any
speed irregularities and sticky sensation. This may
indicate dirt in the fluid. If the steering wheel continues to
rotate when started and released, a condition known as
Motoring exists. This may also indicate dirty fluid in the
system.
3. Ensure the system has adequate power. If there is an
indication of hard steering, this can be caused by either
a reduced oil flow to the control valve or a reduced
Symptom Probable Cause Solution
1. Hard to steer left and
right. a. Hydraulic oil low. a. Check system for leaks. Make
repairs as needed. Fill reservoir.
b. Clogged or loose hydraulic lines or
fittings. b. Clean or tighten lines or
fittings.
c. Defective flow divider valve(s). c. Repair or replace valve(s).
d. Defective steering control valve. d. Repair or replace valve.
e. Defective hydraulic pump. e. Repair or replace pump.
2. Hard to steer either left
or right. a. Clogged or loose hydraulic lines or
fittings. a. Clean or tighten lines or
fittings.
b. Defective steer cylinder. b. Repair or replace cylinder.
3. Steering is erratic left
and right. a. Hydraulic oil low. a. Check system for leaks. Make
repairs as needed. Fill reservoir.
b. Clogged or loose hydraulic lines or
fittings. b. Clean or tighten lines or
fittings.
c. Defective steering control valve. c. Repair or replace valve.
d. Defective hydraulic pump. d. Repair or replace pump.
4. Noisy hydraulic pump
caused by cavitation. a. Hydraulic oil low. a. Refill hydraulic reservoir. Refer to
Lubrication , page 9-1.
b. Suction line plugged or too small. b. Clean line and check for size.
5. Hydraulic pump shaft
seal
leakage. a. Worn shaft seal.
NOTE: If replacing the shaft seal does not
stop leakage, the pump should be
disassembled and checked for the
following:
a. Replace shaft seal.
b. Broken diaphragm seal or backup
gasket. b. Replace seal or gasket. Refer to your
M a n i t o w o c C r a n e C a r e P a r t s
Manual.
c. Bearing out of position. c. Replace bearing.
d. Excessive internal wear. d. Replace pump.