Manitowoc Published 09-10-14, Control # 065-24 1-51
14000 SERVICE MANUAL INTRODUCTION
Lowering
When drum 3 control handle is moved forward for lowering,
an input voltage of 2.4 volts or less is sent to node 1
controller. Node 4 controller sends a 24 volt output to enable
drum 3/left travel diverting solenoid HS-10. Node 3 controller
sends a variable 0 to 24 volt output that is divided by
resistors and applied to drum 3 pump EDC in raising
direction. Node 3 controller sends a variable 0 to 24 volt
output that is applied to drum 3 motor PCP. Node 1 controller
checks that drum block-up limit switches are closed and no
system faults are present.
Pump EDC tilts swashplate in raising direction to satisfy
pressure memory. Node 1 controller compares drum holding
pressure to value in pressure memory. When system
pressure is high enough, node 3 controller sends a 24 volt
output to enable drum 3 brake release solenoid HS-7. Drum
brake solenoid shifts to block drain port and opens port to
low-pressure side of drum system to release brake from
drum shaft.
Drum 3 pump EDC tilts swashplate in lowering direction as
hydraulic fluid flows from pump outlet port A to motor inlet
port. Return fluid is from motor outlet port to pump inlet port
B.
Node 4 controller output voltages to pump EDC and node 3
controller output voltage to motor PCP is relative to control
handle movement. As control handle is moved back, an
output voltage increases pump swashplate angle.
When system pressure exceeds the ECOR (electric
compensating over-ride) valve setting of 3600 psi (248 bar),
the valve shifts to direct flow from shuttle valve into maximum
displacement side of servo cylinder. The ECOR valve over-
rides the command from servo PC valve, increasing motor
displacement and output torque and reducing output speed.
When ECOR valve closes, control of the motor returns to
servo PC valve.
Node controllers continuously balance drum system
pressures and monitor motor displacement angle so motor
displacement goes to minimum when control handle is fully
forward, if motor torque requirements is not too high. Node 1
controller monitors motor displacement and controls motor
speed by regulating hydraulic fluid flow through the pump.
When drum 3 control handle is moved toward neutral
position, node 1 controller compensates for hydraulic system
leakage or changing engine speed. This shifts motor back to
maximum displacement for slower output speed to slow
drum rotation.
When control handle is moved to neutral position, node 4
controller sends a zero output voltage to pump EDC that
moves swashplate to center position. Node 1 controller
stores the load holding pressure in pressure memory. After
control handle center switch opens, Node 3 controller sends
a zero output to disable brake release solenoid HS-7. Drum
brake solenoid valve shifts to block pilot pressure to brake
and opens a line to tank. When brake applies, an input signal
is sent to node 1 controller. Node 3 controller sends a zero
volt output to drum 3 pump EDC to de-stroke pump.
Drum 3/left travel diverting solenoid HS-10 remains enabled
until left travel handle is moved.
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