National Crane 600H, Руководство по обслуживанию

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HYDRAULIC SYSTEM SERVICE MANUAL 600H
2-4
08-19-2022 Control # 092-13
HYDRAULIC SYSTEM DESCRIPTION
The hydraulic system is an open center type consisting of a
fixed displacement three section high pressure pump which
supplies oil to a main control valve and a hoist control valve.
The main control valve is equipped with a main inlet and a
mid inlet. The main inlet supplies oil to the turn function, the
mid inlet supplies the remainder of the crane function
requirements. The main control valves contain inlet section
reliefs or port reliefs which limit pressure in the hydraulic
system to acceptable levels and control crane movements.
See Specification Section for pressure settings.
The large single section control valve supplies oil to hoist up
and down. The inlet section contains a screw adjustable
main relief. The first work section of the multi-section main
control valve controls turn right and left. This work section is
supplied oil by the main inlet section which contains a screw
adjustable relief valve. The remaining work sections are
boom telescope, boom lift, and outrigger functions in that
order. The oil to these sections is supplied by the mid inlet
section which also contains a main relief valve. The hoist and
the main circuits are all connected through shuttles to a
pressure gauge located on the control console.
The hydraulic oil is supplied by a truck frame mounted oil
reservoir, which is equipped with a replaceable canister type
return oil filter. The truck power take off driven hydraulic
pump is sized to supply 34 GPM (129 Lpm) to the hoist
circuit, 18 GPM (68 Lpm) to the boom lift and telescope
circuits and 10 GPM (38 Lpm) to the turn function at 2500
rpm pump shaft speed. Higher pump speeds may result in
excessive heat generation in the hydraulic system. The
pump is not bidirectional and can only be used when the
shaft rotates only in the proper direction. If you need to verify
or change pump rotation, contact your National distributor or
National Crane Product Support.
The crane hydraulic system includes a hydraulic capacity
alert system. This system is a hydraulically operated,
maximum capacity sensing device that monitors lift cylinder
pressure. As pressure in the lift cylinder approaches its
maximum predetermined level, which can be monitored on
the console mounted range gauges, a hydraulic pressure
switch activates an integral hydraulic dump circuit in the
main control valve, disabling the crane functions which
increase the over capacity condition.
All load bearing cylinders on this machine are protected from
inadvertent movement or collapse due to hose failure by pilot
operated check valves or by pilot operated counterbalance
valves if overhung loads must be controlled.
The standard swing gearbox is locked in place by an integrally
mounted spring applied brake and a dual counterbalance motor
holding valve. The swing brake and counterbalances are piloted
open and closed by operating swing left or right and are
automatically reapplied by ceasing the swing function.
Maximum swing speed can be limited using the swing speed
adjustment valve.
GENERAL ADJUSTMENT AND REPAIR
PROCEDURES
Before adjustments and repairs are started on a crane, the
following precautions shall be taken as applicable:
• Place a warning tag in a conspicuous place at the
controls stating that the machine requires adjustment or
repair before it can be operated.
• Park the crane where it causes the least interference
with other equipment or operations in the area.
• Place all controls at the off position and secure all
operating features from inadvertent motion by brakes or
other means.
• Disable all methods used to start the truck's engine.
• Power plant stopped or disconnected at take-off.
• Boom lowered to the ground or otherwise secured
against dropping.
• Load block lowered to ground or otherwise secured
against dropping.
• Relieve hydraulic oil pressure from all hydraulic circuits
before loosening or removing hydraulic components.
After adjustments and repairs have been made, the crane
shall not be returned to service until all guards have been
reinstalled, trapped air removed from hydraulic system if
required, safety devices reactivated, and maintenance
equipment and all warning tags removed.
Adjustments and repairs shall be done only by designated
personnel who are properly trained. Use only National Crane
supplied parts to repair the crane.
Hydraulic System Maintenance Precautions
Contaminants in a hydraulic system affect operation and can
result in serious damage to the system components. If
evidence of foreign particles is found in the hydraulic system,
flush the system.
Disassemble and assemble hydraulic components on a
clean surface. Clean all metal parts in a nonflammable
cleaning fluid. Lubricate all components to aid in assembly.
Inspect all sealing elements (O-ring, gaskets, etc.) when
disassembling and assembling the hydraulic system
components. Installation of new sealing elements is always
recommended.
When installing metal hydraulic tubes, tighten all bolts finger
tight. Then, in order, tighten the bolts at the rigid end, the
adjustable end, and the mounting brackets. After tubes are
mounted, install the hoses. Connect both ends of the hose
with all bolts finger tight. Position the hose so it does not rub
the machine or another hose and has a minimum of bending
and twisting. Tighten bolts in both couplings.
REFERENCE ONLY