INTRODUCTION 16000 SERVICE/MAINTENANCE MANUAL
1-42
Published 05-03-17, Control # 228-03
When the drum control handle is moved to the neutral
position, the Node-1 controller compensates for the
hydraulic system leakage or changing engine speed. The
Node-3 controller sends a zero output voltage to the pump
EDC that moves the swashplate to the center position. This
shifts the motor back to the maximum displacement for
slower output speed to slow the drum rotation.
When the control handle is moved to the neutral position, the
Node-1 controller stores the load holding pressure in the
pressure memory. After the drum 3 control handle center
switch opens, the Node-6 controller sends a zero output
voltage to disable the drum brake release solenoid HS-25.
The drum brake solenoid valve shifts to block the pilot
pressure to the brake and opens a line to the tank. The brake
applies before the drum pump de-stroke.
When the brake applies, an input signal is sent to the Node-1
controller. The Node-3 controller sends a zero volt output to
the pump EDC to de-stroke the pump. The Node-6 controller
sends a zero volt output to the motor PCP.
The left travel handle to the drum 3 diverting solenoid HS-28
remains enabled until the left travel handle is moved.
Lowering
See Figure 1-27 and Figure 1-28.
When the drum 3 control handle is moved forward for
lowering, an input voltage of 2.4 volts or less is sent to the
Node-1 controller. The Node-4 controller sends a 24 volt
output to enable the left travel to drum 3 diverting solenoid
HS-28. The Node-3 controller sends a variable 0 to 24 volt
output that is divided by a resistor and applied to the pump 2
EDC in the raising direction. The Node-6 controller sends a
variable 0 to 24 volt output that is divided by a resistor and
applied to the motor PCP. The Node-1 controller checks that
the drum block-up limit switches are closed and no system
faults are present.
The pump EDC tilts the swashplate in the raising direction to
satisfy the pressure memory. The Node-1 controller
compares the drum holding pressure to the value in the
pressure memory. When the system pressure is high
enough, the Node-6 controller sends a 24 volt output to
enable the drum 3 brake release solenoid HS-25. The drum
brake solenoid shifts to the block the drain port and opens
the port to low-pressure side of drum system to release the
brake from the drum shaft.
The pump EDC tilts the swashplate in the lowering direction
as the hydraulic fluid flow is from the pump port to the motor
port. Return fluid is from the motor outlet port to the pump
inlet port.
The Node-3 controller output voltages to the pump EDC and
the Node-6 controller output voltage to the motor PCP is
relative to the control handle movement. As the control
handle is moved back, an output voltage increases the pump
swashplate angle.
When system pressure exceeds the PCOR (Pressure
Compensating Over-Ride) valve setting of 340 bar (4,931
psi), the valve shifts to direct flow from the shuttle valve into
the maximum displacement side of the servo cylinder. The
PCOR valve over-rides the command from the servo PC
valve, increasing the motor displacement and the output
torque while reducing the output speed. When the PCOR
valve closes, motor control returns to the servo PC valve.
Node controllers continuously balance the drum system
pressures and monitor the motor displacement angle so the
motor displacement goes to the minimum when the control
handle is fully forward, if the motor torque requirements are
not too high. The Node-1 controller monitors the motor
displacement and controls the motor speed by regulating the
hydraulic fluid flow through the pump.
When the drum control handle is moved to the neutral
position, the Node-1 controller compensates for hydraulic
system leakage or changing engine speed. The Node-3
controller sends a zero output voltage to the pump EDC that
moves the swashplate to the center position. This shifts the
motor back to the maximum displacement for slower output
speed to slow the drum rotation.
When the control handle is moved to the neutral position, the
Node-1 controller stores the load holding pressure in the
pressure memory. After the control handle center switch
opens, the Node-4 controller sends a zero output to disable
the brake release solenoid HS-25. The drum brake solenoid
valve shifts to block the pilot pressure to the brake and opens
a line to the tank. When the brake applies, an input signal is
sent to the Node-1 controller. The Node-3 controller sends a
0 volt output to the drum pump EDC to de-stroke. The Node-
6 controller sends a zero volt output to the motor PCP. The
left travel to drum 3 diverting solenoid HS-28 remains
enabled until the left travel handle is moved.
FIGURE 1-27
HS-25
HS-27
HS-28
Brake
Diverting
Valve
Motor
(PCP)
Pump
(EDC)
Pressure
Sender
Pawl
HS-26
16-1022
Accessory Pump
(Low-Pressure)
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