Manitowoc Published 09-10-14, Control # 065-24 1-41
14000 SERVICE MANUAL INTRODUCTION
DRUM 2 (REAR DRUM) SYSTEM
See Figure 1-24 and Figure 1-25 for the following procedure.
Drum 2 is located at the middle top of rotating bed. One
hydraulic pump drives one motor gearbox on end of drum.
Hydraulic connections between pump and motor form a
closed-loop system that is controlled with control handle
movement and node controllers. The center load drum
control handle on right side console operates drum 2. The
control handle is inoperable when drum 2 park brake is
applied.
Charge pressure from system pump supplies hydraulic
make-up fluid to closed-loop. Low-pressure side supplies
hydraulic pilot pressure to operate motor servo. 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 smooth drum operation.
When load drum 2 motor rotates, a speed sensor at motor
rotor (non free fall) or the drum flange (free fall) monitors and
sends an input voltage to node 1 controller to control drum
operation. Node 2 controller sends an output voltage to
rotation indicator in control handle. As drum rotates faster,
rotation indicator on top of control handle pulsates with a
varying frequency that indicates drum rotational speed.
Handle command in percent from neutral is shown on
Diagnostic Screen.
Continuous changing of closed-loop fluid occurs with
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
discharging exhausted fluid into motor case where the fluid
returns to tank.
Drum 2 Brake
Hydraulic pressure to operate drum 2 brake is from low-
pressure side of system. When drum 2 brake switch is in on -
park position, drum brake release solenoid HS-4 is disabled
so brake is applied to drum shaft. Drum pump does not
stroke in response to control handle movement.
When drum 2 brake switch is placed in off - park position,
brake release solenoid HS-4 remains applied. Brake
remains applied until node 4 controller sends a 24 volt output
to release brake. Drum circuit is active, waiting for a control
handle command.
Raising Load
When drum 2 control handle is moved back for raising, an
input voltage of 2.4 volts or less is sent to node 1 controller.
Node 4 controller sends a variable 0 to 24 volt output that is
divided by resistors and applied to drum 2 pump EDC in the
raising direction. Node 4 controller sends a variable 0 to 24
volt output that is applied to 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 4 controller sends a 24 volt
output to enable drum 2 brake release solenoid HS-4. Drum
brake solenoid shifts to block drain port and opens port to
low-pressure side of drum system to release brake from
drum shaft.
Pump EDC tilts swashplate in raising direction as hydraulic
fluid flow is from pump port B to motor port. Return fluid is
from motor outlet port to pump inlet port A.
Node 4 controller output voltage to pump EDC and to motor
PCP is relative to control handle movement. As control
handle is moved back, an output voltage increases the 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 all the
way back, if motor torque requirements is not too high.
Node 1 controller monitors motor displacement and controls
motor speed by regulating the hydraulic fluid flow through the
pump.
When drum 2 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 drum 2 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 4 controller sends
a zero output voltage to disable drum 2 brake release
solenoid HS-4. Drum brake solenoid valve shifts to block
pilot pressure to brakes and opens a line to tank. When
brake applies, an input signal is sent to node 1 controller.
Node 4 controller sends a zero volt output to pump EDC to
de-stroke pump.
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