Manitowoc Published 05-03-17, Control # 228-03 1-53
16000 SERVICE/MAINTENANCE MANUAL INTRODUCTION
Mast Raising from Transport Position
See Figure 1-44 and Figure 1-45.
Use the RCL Screen to select the Liftcrane Mast Handling
Capacity Chart. The mast controls will not operate and the
mast operating limits remain off until the Liftcrane Mast
Handling Capacities Chart is selected.
Use the mast switch on the hand-held wireless remote to
raise the mast assist arms until the cylinders stall and stop.
When the boom/mast hoist 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-3 controller sends a
variable 0 to 24 volt output that is divided by a resistor and
applied to the boom/mast hoist pump EDC in the down
direction.
The Node-4 controller sends a 24 volt output to enable the
mast cylinders extend solenoid HS-50 and shifts the valve to
the extend position. The Node-3 controller sends a variable
0 to 24 volt output to enable the accessory system
proportional relief solenoid HS-68.
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-4 controller sends a 24
volt output to drum brake solenoid HS-10. The drum brake
valve shifts to block the drain port and opens the port to the
low-pressure side of the pump to release the brake.
The boom/mast hoist pump EDC strokes the pump in the
down direction. The Node-4 controller sends a 24 volt output
to enable the mast raising cylinders solenoid HS-50 in the
extend (mast raising) direction. The valve shifts to block the
tank port and open the port to the accessory system
pressure. The Node-3 controller sends a variable 0 to 24 volt
output to enable the accessory system proportional relief
solenoid HS-68.
The mast assist arm cylinders extend automatically as the
mast raises from the transport position. The boom/mast hoist
drum pays out the wire rope between the drum and the mast
sheaves. A speed sensor at motor rotor monitors the drum
rotational speed.
Fluid pressure from the accessory valve enters the free-flow
check valve sections on side A of the load equalizing valve.
From the equalizing valve, fluid enters the counterbalance
valves and piston end of the mast cylinders, extending the
cylinder rods to raise the mast. The Node-4 controller
monitors the accessory system pressure to control the mast
cylinder raising the speed rate.
Fluid flow from the rod end of the mast raising cylinders is
blocked by the free-flow check valve sections on side B of
the counterbalance valves and flows through the valve flow
restrain sections preset for a relief pressure of 240 bar
(3,481 psi). The counterbalance valves operate with a 5:1
pilot ratio of the relief valve pressure, permitting the valve to
open when the pressure in rod end of the cylinders is
approximately 48 bar (696 psi). Hydraulic fluid from side B
sections of both the counterbalance valves combines, and
the free-flow check valve section on side B of load equalizing
valve blocks the flow.
The fluid then passes through the valve flow restrain section
that is preset at 276 bar (4,003 psi). The load equalizing
valve operates with a 1.5:1 pilot ratio of the relief valve
pressure, permitting the valve to open when the hydraulic
pressure on side A of the load-equalizing valve is
approximately 185 bar (2,683 psi). The restraining section on
side B of the load equalizing valve opens, controlling the flow
of fluid out of the cylinders to ensure the cylinder operation is
balanced.
When the mast cylinders are extending, the Node-4
controller monitors the drum speed sensor. The Node-1
controller maintains a speed that is proportional to the
accessory system hydraulic pressure applied to the mast
raising cylinders. The mast assist arms will stop rising
automatically when the mast assist cylinders are fully
extended (approximately 115°).
The Node-3 controller monitors the mast angle sensor when
the mast is moving. The diagnostic screen monitors the mast
operating angle. When the mast is raised to the operating
range of 115° to 145°, the Node-3 controller sends a zero
output voltage to the pump EDC. When the control handle
center switch opens, the Node-4 controller sends a zero volt
output to disable the brake solenoid HS-10 to apply the
brake before pump de-strokes.
The Node-3 controller sends a variable 24 volt output signal
to the pump EDC to de-stroke the pump. The Node-4
controller sends a zero output voltage to shift the spool of
mast raising cylinder solenoid HS-50 to the center position.
The Node-3 controller sends a zero volt output to disable the
accessory system proportional relief solenoid HS-68.
FIGURE 1-44
Pressure
Sender
Accessory
Pump
Mast Raising
Cylinders
HS-68
HS-51
HS-50
Pressure
Sender
Drum 4
Pump
Drum 4
Motors
HS-10
16-1037
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