Manitowoc National Crane NBT40 Series User Manual

National Crane Published 4-23-2018 Control # 239-11 6-7
6
NBT40 SERIES OPERATOR MANUAL MAINTENANCE CHECKLIST
Condition Possible Cause Possible Solution
No response to control
RCL system inoperative.
Insure the RCL system is working properly and
the anti-two-block solenoid is powered.
Load too heavy. Check load chart.
PTO not engaged. Engage PTO.
Low hydraulic fluid supply. Check and fill as required.
Suction line blocked. Drain tank and hose and remove blockage.
Broken hydraulic pressure line. Replace as required.
Defective hydraulic pump. See Pump Service Manual.
Incorrect relief valve setting. Adjust relief).
Relief valve sticking. Clean relief.
Poor hydraulic system
performance
Pump not operating at proper speed.
Check PTO ratio, pump size and engine speed
for proper oil flow.
Low hydraulic fluid supply. Check and fill as required.
Relief valve sticking. Remove and clean.
Relief setting too low. Readjust to proper setting.
Worn pump, motor or cylinder. Replace bad part.
Plugged filter. Change filter.
Boom holding valves out of adjustment. Adjust or clean as required.
Oil temperature too high.
Run engine at idle with controls in the neutral
position until hydraulic oil light goes out.
Hydraulic oil too cold or dirty. Warm oil or use less viscous oil.
Line restricted. Check lines; clean and repair as required.
Internal control valve crack. Replace valve.
Load too heavy. Check load chart and reduce load.
Swing moves erratic or
sloppily (Standard system).
Loose turntable bearing. Torque bearing mounting bolts.
Loose swing gearbox mounting bolts. Tighten bolts.
Worn gears or bearing. Replace worn parts or adjust gearbox spacing.
Operator control of lever too erratic. Operate controls smoothly.
Motor counterbalance valves dirty or not
set properly.
Clean or replace counterbalance valves.
Brake not holding properly.
Replace worn brake parts or shim brake to
proper torque.
Brake releasing at wrong time or erratically.
Bleed air from brake with bleed screw on side of
brake.
Swing speed adjustment set too low.
Adjust or clean brake for proper release.
Adjust valve on turn motor.

Manitowoc National Crane NBT40 Series Specifications

General

Brand	Manitowoc
Model	National Crane NBT40 Series
Category	Construction Equipment
Language	English