Manitowoc Grove RT770E Service Maintenance Manual page 291

RT770E
Maintenance
Troubleshooting
Table 8-3
Symptom
1. Brakes are poor.
2. Hard brake pedal with engine
running.
3. Brakes lock up.
4. Uneven braking or pad wear.
General
A schedule for the periodic adjustment, cleaning, inspection,
and lubrication of brake equipment should be established by
the operator on the basis of past experience and severity of
operation.
The disc brakes are not adjustable. Brakes should be
cleaned, inspected, and linkage lubricated periodically to
assure maximum performance.
GROVE
Probable Cause
a. Lining thickness less than
0.125 in (3 mm).
b. Brake pedal operation.
c. Restriction or leaks in lines.
d. Low hydraulic oil flow.
e. Air in brake lines.
f. Brake pads/linings
grease-soaked.
g. Engine not running.
h. Brake relief valve stuck open.
i. Dual accumulator
valve not charging
j. Accumulators not
charged.
a. Pedal travel being interfered
with.
a. Too much hydraulic flow.
b. Brake pedal push
improperly adjusted, causing
brakes to be always applied.
a. Lining thickness less than
0.125 in (3 mm).
b. Grease on the pads/linings.
Bleeding the Brake System
The brake system should be bled whenever air becomes
entrapped within the brake system (usually characterized by
a spongy feeling during brake pedal application), whenever
any brake system line has been opened, or whenever any
brake component has been replaced.
Always start at the point in the system that is furthest from
the tandem brake valve and work back toward the tandem
Published 11/26/2014, Control # 447-05
UNDERCARRIAGE
Solution
a. Replace lining.
b. Free mechanical linkage.
c. Check all lines for leaks and
restrictions.
d. Check the hydraulic oil level in
reservoir and check flow from
the tandem brake valve.
e. Bleed the brakes.
are f. Replace pads/linings.
g. Start engine. Due to the
operation, the engine must be
running to provide full brake
power.
h. Replace the relief valve.
charge i. Check valve operation and
repair or replace valve.
pre- j. Check
charge.
a. Check all pedal linkage and
ensure it is free and adjusted
properly.
a. Check the flow from the flow
divider. Too much flow will
c a u s e t h e b r a k e s t o b e
applied by the oil trapped in
the power boost chamber.
rod b. Adjust the push rod linkage so
the brake pedal and push rod
fully return.
a. Replace the lining.
b. Replace the pads/linings.
accumulator pre-
8
8-15