
Reference
Only
INTRODUCTION
18000 SERIVCE/MAINTENANCE MANUAL
1-60
Published 12-05-17, Control # 035-23
LUFFING JIB DRUM 6 (OPTIONAL) SYSTEM
Luffing Jib System Components
See Figures
One hydraulic pump drives one hydraulic motor and gearbox
on luffing jib drum. In Luffing Jib mode luffing jib hoist (Drum
6) is controlled with control handle on left side console, while
the boom hoist (Drum 4) is controlled by control handle on far
right of right side console. Luffing jib control handle is
inoperable when luffing jib park brake is applied.
Hydraulic charge pressure from left travel charge pump
supplies hydraulic pilot pressure to operate luffing jib motor
servo. Hydraulic charge pressure from system charge pump
supplies hydraulic make-up fluid to low-pressure side of
luffing jib motor. A pressure sender in high-pressure side of
pump leg provides system pressure information to node-1
controller. A fixed orifice between pump ports A and B allows
for smoother drum operation.
When luffing jib motor rotates, a speed sensor monitors
motor rotor movement and sends an input voltage to node-1
controller. Node-2 controller sends a 24 volt output to
rotation indicator in control handle. As luffing jib drum rotates
faster, the rotation indicator on top of control handle pulsates
with a varying frequency that indicates drum rotational
speed.
Continuous changing of closed-loop fluid occurs through
leakage in pump, motor, and external sequence/flow valve.
Sequence/flow valve opens at 200 psi (14 bar) and removes
4 gallons per minute (15 l/m) of hot fluid from system by
dumping the fluid into the motor case where fluid returns to
tank.
Luffing Jib Brake and Pawl
Hydraulic pressure to operate luffing jib brake is from low-
pressure side of luffing jib system. An electrical motor
operates the boom hoist drum pawl.
When luffing jib (Drum 6) brake switch is in on - park position,
luffing jib brake solenoid valve HS-15 is disabled to apply
brake to drum. Luffing jib electric drum pawl in relay K1 is
enabled to keep pawl applied to boom hoist drum. Boom
hoist pump does not stroke in response to boom hoist control
handle movement.
When luffing jib (Drum 6) brake switch is placed in off - park
position, luffing jib brake remains applied to luffing jib drum
until node-8 controller sends a 24 volt output to brake
solenoid valve HS-15 to release brake. Node-8 controller
sends 24 volt output to enable luffing jib pawl electric motor
K2 relay in the pawl out direction. Luffing jib system circuit is
active, waiting for a control handle command.
Luffing Jib Raise
Node-1 controller checks that luffing jib up limit switch is
closed and no hydraulic system fault is present. If a block up
limit or RCL operating fault occurs while luffing, node-1
controller sends an output signal to stop luffing jib drum.
Corrective action for these operating faults is to raise the jib.
When luffing jib control handle is moved back for luffing
up
,
an input voltage of 2.4 volts or less is sent to node-1
controller. Node-5 controller sends a variable zero to 24 volt
output that is divided by a resistor and applied to luffing pump
EDC. Node-8 controller sends a variable zero to 24 volt
output that is divided by a resistor and applied to luffing
motor PCP.
Pump EDC tilts swashplate in the
up
direction to satisfy
pressure memory. Node-1 controller compares luffing
holding pressure to value in pressure memory. When system
pressure is high enough, node-8 controller sends a 24 volt
output to luffing jib brake solenoid valve HS-15. The brake
solenoid shifts to block drain port and opens port to low-
pressure side of luffing jib system to release luffing jib drum
brake.
Pump EDC continues to tilt swashplate in the up direction as
hydraulic fluid flow is from port B of pump to port A of motor.
Return fluid is from port B of motor to port A of pump.
Node-5 controller output voltage to pump EDC and node-8
controller output voltage to motor PCP is relative to control
handle movement. As luffing jib control handle is moved
back, pump swashplate angle is increased. When system
pressure exceeds the PCOR (Pressure Compensating Over-
Ride) valve setting of 4,930 psi (340 bar), the valve shifts to
direct flow from shuttle valve into maximum displacement
side of servo cylinder. The PCOR valve over-rides the
c om m an d f r o m s e r v o P C v a l v e, i nc r ea s i ng m o t or
displacement and output torque and reducing output speed.
When PCOR valve closes, control of the motor returns to
servo PC valve.
Node controllers are continuously balancing system
pressure and motor displacement angle so the motor
displacement goes to minimum when control handle is all the
way back, if the motor torque requirement is not too high.
Node-6 controller monitors motor displacement and controls
motor speed by regulating hydraulic fluid through the pump.
When luffing jib control handle is moved to neutral position,
node-1 controller compensates for hydraulic system leakage
or changing engine speed. Node-5 controller sends a zero
output voltage to luffing jib pump EDC that moves
swashplate to center position. This shifts the motor back to
maximum displacement for slower output speed to slow the
drum rotation. The controller stores the load holding
pressure in pressure memory. After control handle center
switch opens, a zero output voltage is sent to disable luffing
brake solenoid valve HS-15 to apply brake before pump de-
strokes.
Содержание 18000
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