Manitowoc Published 10-01-2012, Control # 045-08 10-1
777 SERVICE MANUAL TROUBLESHOOTING
10
SECTION 10
TROUBLESHOOTING
INTRODUCTION
This troubleshooting section is designed for qualified service
technicians familiar with the operation and repair of electrical
and hydraulic equipment. It is not possible to predict all
problems that might occur or the correct procedure for
troubleshooting each problem. If a problem is encountered
that is not covered in this manual, first consult your
Dealer. The factory Service Department can provide
assistance, if necessary.
The first part of this section provides a series of flow charts
that identify problems that could be encountered during
normal operation of the Model 777. These charts contain
instructions to assist in identifying and correcting problems.
Follow the procedural steps in the order indicated. Some
steps direct you to other charts in this manual or reference a
specific test that must be performed to move through the
complete troubleshooting procedure. If directed, consult the
dealer or factory Service Department before proceeding.
The second part of this section contains specific instructions
for testing and servicing the various systems and
components described in the troubleshooting charts.
SAFETY SUMMARY
Hazards are always a possibility when performing trouble-
shooting operations on heavy equipment. To minimize the
risk of potential hazards and to prevent serious injury or
death, you must comply with the following:
• Carefully read the Section 1 of this manual before
beginning troubleshooting operations.
• You must be a qualified service technician, competent in
the repair and testing of electrical and hydraulic
equipment. MANITOWOC CRANES INC. shall not be
responsible for the training of personnel who might use
this manual to perform the troubleshooting operations.
• Whenever possible, turn off the engine for your
protection and keep unauthorized personnel away from
the crane when troubleshooting.
• Never troubleshoot the crane alone. Always perform
troubleshooting procedures with a qualified operator in
the crane cab. Maintain constant communications with
this operator when performing operations that require
the crane to be running.
• Do not return crane to service after completion of
maintenance or repair procedures until all guards and
covers have been re-installed, trapped air is bled from
hydraulic systems, safety devices are re-activated and
maintenance equipment is removed.
• Perform a function check to ensure correct operation at
the completion of maintenance or repair operations.
The following warnings apply to all troubleshooting
operations. MANITOWOC CRANES INC. can not foresee all
hazards that may occur.
You must be familiar with the equipment, trained in testing
methods, and use common sense while troubleshooting to
avoid other hazards.
GENERAL GUIDELINES
The following guidelines apply to all troubleshooting
operations:
• Do not remove cylinders or counterbalance valve(s)
from a cylinder until its working unit is restrained against
movement.
• Do not use your hands to check for hydraulic oil leaks.
Use a piece of cardboard to check for hydraulic oil leaks.
• Use gauges of the correct pressure range when
checking hydraulic circuits.
WARNING
Eye, Skin, And Respiratory Hazards!
Wear proper eye and skin protection and avoid direct
contact with battery acid, oil, or ether spray when
searching for leaks, opening connections, or installing
pressure gauges.
Pressurized hydraulic oil can cause serious injury. Turn
off engine, remove key, and relieve pressure on system
before disconnecting, adjusting, or repairing any
component.
Ensure that connections are made correctly, O-rings or
gaskets are in place, and connectors are tight before
pressurizing system.
Use necessary precautions to prevent electrical burns
when checking battery charging and starter circuits.
Death or serious injury can occur if these warnings are
ignored.
WARNING
Unexpected Moving Part Hazard!
Keep personnel away from crane while manually
actuating a valve or pump to avoid unexpected equipment
movement that can cause death or serious injury.
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