Manitowoc Grove YB5515-2, Service And Maintenance Manual

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CD5515-2/YB5515-2 SERVICE MANUAL
9-20
Published 1-20-2017, Control# 483-02
TROUBLESHOOTING
Service Brakes
PROBLEM POSSIBLE CAUSE REMEDY
Warning light on instrument panel
illuminates. 1. Loss of brake pressure. 1. Any cause under NO BRAKES.
No brakes. 1. Faulty brake modulating valve.
2. Faulty priority flow control valve.
3. Loss of fluid from broken line,
loose fitting of hose.
4. Leakage past both brake pistons.
5. Faulty pump section.
6. Faulty accumulator charging
valve.
1. Repair or replace.
2. Replace.
3. Check all circuit lines, hoses and
fittings. Tighten or replace.
4. Perform leakage test.
5. Replace pump.
6. Replace valve.
Bad brakes (pedal fully applied, crane
gradually stops). 1. Severe wear in service brake
discs.
2. Leakage past one brake piston.
1. Replace brake discs. See Section
8.
2. Perform leakage test. Repair or
replace. See Section 7.
Soft brake pedal. 1. Air in system.
2. High pressure leaks - external.
1. Bleed brake system.
2. Apply full brake pressure, inspect
for leakage in lines, hoses and
fittings.
Charging valve actuates every time
foot pedal is pressed. 1. Accumulator needle valve closed.
2. Loss of nitrogen in accumulator.
3. Insufficient hydraulic pressure in
accumulator.
1. Open needle valve.
2. Charge accumulator.
3. Faulty accumulator charging
valve. Replace.
Parking brake will not release. 1. Faulty solenoid valve.
2. Loss of fluid from broken line,
loose fitting or hose.
3. Faulty priority flow control valve.
4. Faulty parking brake switch.
5. Loose electrical connections.
6. Faulty pump section.
1. Replace solenoid valve.
2. Check all circuit lines, hoses and
fittings. Tighten or replace.
3. Replace.
4. Replace switch.
5. Check and tighten.
6. Replace pump.
Parking brake will not hold. 1. Improperly adjusted parking
brake.
2. Severely worn brake linings.
3. Faulty parking brake assembly.
1. Adjust brake lining clearance.
2. Replace brake linings.
3. Repair or replace.
Reference Only