Manitowoc National Crane NC1400H - Page 122

SERVICE 1400H OPERATOR AND SERVICE MANUAL
5-10 Published 10-30-2014 Control # 040-09
TROUBLE DIAGNOSIS (continued)
CONDITION POSSIBLE CAUSE POSSIBLE SOLUTION
Turn moves
erratic or
loosely
• Loose turntable bearing.
• Loose swing gearbox mounting bolts.
• Worn gears or bearing.
• Operator control of lever too erratic.
• Motor counterbalance valves dirty or not set
properly.
• Brake not holding properly.
• Brake releasing at wrong time or erratically.
• Torque bearing mounting bolts.
• Tighten bolts.
• Replace worn parts or adjust gearbox spacing.
• Operate controls smoothly.
• Clean or replace counterbalance valves not set at
600 psi.
• Check for no pressure in brake pilot line when turn
is in neutral.
• Replace worn brake parts or shim brake to proper
torque.
• Bleed air from brake with bleed screw on side of
brake.
Turn will not
function
• Attempting to swing up too much of incline.
• Turn circuit relief valves sticking.
• Turntable bearing drag.
• Brake not releasing properly.
• Swing speed adjustment set too low.
• Level machine.
• Clean and check circuit pressure.
• Lubricate thoroughly as rotating boom.
• Check for 200 + psi (1,4 MPa) brake pilot
pressure. Clean pilot line or adjust motor
counterbalance valves.
• Adjust or clean brake for proper release.
• Adjust valve on turn motor.
Excessive noise
during
operation
• Low oil temperature.
• Low hydraulic oil supply.
• Suction line kinked, collapsed or blocked.
• Hydraulic oil too thick.
• Plugged suction strainers.
• Relief valve chattering.
• Swing brake dragging.
• Hydraulic tubing vibration.
• Tank breather plugged.
• Allow unit to warm up.
• Check and fill with crane in travel position.
• Clear blockage.
• Warm oil or use oil more applicable to
environment.
• Remove from tank and clean.
• Dirt in relief valve or damaged relief.
• Bleed air from brake line at fitting on brake
housing.
• Check for loose tubing.
• Clean breather.
Cylinders drift • Worn or damaged piston seals.
• Air in hydraulic oil.
• Loose holding valve.
• Dirt in holding or check valve.
• Replace as required.
• Cycle operate crane cylinder to remove air.
• Tighten valve.
• Clean valve.
Reference Only