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2
National Crane
03-20-2019 Control # 613-06
2-27
NBT30H-2 SERVICE MANUAL
HYDRAULIC SYSTEM
Pressure or Flow
Instability
Check for air in system.
Air in system causes erratic
operation.
Activate pressure compensation
allowing system to bleed air.
Check inlet line for leaks and
eliminate source of air ingression.
Check control spools.
Sticking control spools cause
erratic operation.
Inspect spools for free movement
in bore. Clean or replace.
Check load sense setting.
Low load sense setting may
cause instability.
Adjust load sense setting to proper
level.
Check load sense signal line.
Blocked load sense signal line
interferes with proper load sense
operation.
Remove blockage.
Check external relief valve and
pressure compensation
setting.
Insufficient pressure differential
between pressure compensation
setting and external relief valve.
Adjust external relief valve or
pressure compensation control
settings to appropriate level. Relief
valve setting must be above
pressure compensation setting to
operate properly.
Check external relief valve.
Chattering external relief valve
may cause unstable feedback to
pump control.
Adjust or replace relief valve.
System Pressure not
Reaching pressure
compensation setting
Check pressure compensation
control setting.
System pressure will not rise
above pressure compensation
setting.
Adjust pressure compensation to
appropriate setting.
Check external relief valve.
External relief valve setting
below pressure compensation
setting presents pressure
compensation.
Adjust external relief valve
according to manufacturer’s
recommendations. External relief
valve must be set above pressure
compensation setting to operate
properly.
Inspect pressure
compensation control spring.
Broken, damaged, or missing
spring will cause erratic
operation.
Replace the spring as required.
Inspect pressure
compensation spool for wear.
Wear of pressure compensation
spool causes internal leakage in
the control.
Replace the spool as required.
Inspect pressure
compensation spool for proper
orientation.
Improper orientation results in
poor operation.
Correct orientation of spool.
Check pressure compensation
control for contamination.
Contamination may interfere with
movement of the pressure
compensation spool.
Clean pressure compensation
control components, take
appropriate action to eliminate
contamination.
Troubleshooting Chart (Continued)
CONDITION
ITEM
POSSIBLE CAUSE
POSSIBLE SOLUTION
Содержание National Crane NBT30H-2
Страница 1: ...Service Manual National Crane NBT30H 2 ...
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Страница 40: ...1 30 03 20 2019 Control 613 06 INTRODUCTION NBT30H 2 SERVICE MANUAL ...
Страница 92: ...ELECTRIC SYSTEM NBT30H 2 SERVICE MANUAL 3 24 03 20 2019 Control 613 06 ...
Страница 110: ...BOOM MAINTENANCE NBT30H 2 SERVICE MANUAL 4 18 03 20 2019 Control 613 06 ...
Страница 132: ...SWING NBT30H 2 SERVICE MANUAL 6 14 03 20 2019 Control 613 06 ...
Страница 142: ...OUTRIGGERS NBT30H 2 SERVICE MANUAL 7 10 03 20 2019 Control 613 06 ...
Страница 158: ...LUBRICATION NBT30H 2 SERVICE MANUAL 8 16 03 20 2019 Control 613 06 ...
Страница 190: ...SCHEMATICS NBT30H 2 SERVICE MANUAL 10 2 ...
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