INTRODUCTION 14000 SERVICE MANUAL
1-38
Published 09-10-14, Control # 065-24
DRUM 1 (FRONT DRUM) SYSTEM
See Figure 1-22 and Figure 1-23 for the following procedure.
Drum 1 is located at front 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 first load drum control handle on right
side console operates drum 1. The control handle is
inoperable when drum 1 park brake is applied. Low-pressure
side of drum 1 pump is the pressure source for high pressure
setup and accessory controls.
Charge pressure from system pump supplies hydraulic
make-up fluid to closed-loop. Low-side pressure 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 pressure sender
in low-pressure side of pump leg provides accessory system
information to node 1 controller. A fixed orifice between
pump ports A and B allows for smooth drum operation.
When drum 1 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,
the 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 1 Brake
Hydraulic pressure to operate drum 1 brake is from low-
pressure side of system. When drum 1 brake switch is in on -
park position, drum brake release solenoid HS-1 is disabled
so brake is applied to drum shaft. Drum 1 pump does not
stroke in response to control handle movement.
When drum 1 brake switch is placed in off - park position,
brake release solenoid HS-1 remains applied. Brakes
remain applied until node 3 controller sends a 24 volt output
to release the brake. The drum circuit is active, waiting for a
control handle command.
Raising Load
When drum 1 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 1 pump EDC in the
raising direction. Node 3 controller sends a variable 0 to 24
volt output that is applied to drum 1 motor PCP. Node 1
controller checks that all limit switches are closed and that 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 1 brake release solenoid HS-1. 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 outlet port B to motor inlet port.
Return fluid is from motor outlet port to pump inlet port A.
Node 4 controller output voltage 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 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 hydraulic fluid flow through the
pump.
When drum 1 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 1 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 load holding pressure in pressure memory. After
control handle center switch opens, node 3 controller sends
a zero output to disable drum 1 brake release solenoid HS-1.
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 4 controller sends a
zero volt output to pump EDC to de-stroke pump.
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