Manitowoc National Crane NBT40 Series, Service Manual

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NBT40 SERVICE MANUAL HYDRAULIC SYSTEM
National Crane
Published 8-01-2017 Control # 287-11
2-3
Description Symbol
Manually Operated - Valve shifted
manually with check to allow flow back to
tank.
Pneumatic Operated - Valve shifted by
pneumatic device.
Pilot Operated - Valve shifted by pilot
pressure.
Electric Operated - Valve shifted by
electrical energy.
Brake Valve - Activates swing brake.
Open Center Cylinder Spool - Directional
control valve for hydraulic cylinder
function that directs flow back to tank
through the open center when in the
neutral position
Open Center Motor Spool - Directional
control valve for hydraulic motor function
that directs flow back to tank through the
open center when in the neutral position.
Allows flow back to tank when the crane is
shut down.
Closed Center Cylinder Spool - Pressure
compensated directional control valve for
hydraulic cylinder which directs flow back
to tank with an unloader valve cartridge.
Closed Center Motor Spool - Pressure
compensated directional control valve for
motor with open port for flow back to tank.
Allows flow back to tank when the crane is
shut down.
Single Acting Cylinder - Extended
hydraulically and retracted with a spring.
Double Acting Cylinder - Extended and
retracted hydraulically.
Double Acting Telescope Cylinder - Anchored rod pushes
barrel out when check valve is unseated.
MultiStage Telescope Cylinder - Used in milti-section
synchronized operations.
Inverted Outrigger Jack - Extends the barrel down to
raise the crane off the ground.
Holding Valve - Keeps boom lift cylinder
from collapse if hydraulic pressure failure
occurs (i.e. hose rupture).
Pilot Operated Check Valve (with thermal
relief) - Requires pilot pressure to unseat
the one way check (nonadjustable).
Flow Divider Valve - Regulates flow to a
selected circuit.
Hoist Brake - Holds load after control is
returned to neutral (spring applied and
hydraulically released).
Swing Brake - Spring applied
hydraulically brake holds superstructure
in place.
Description Symbol
Reference Only