Manitowoc Published 05-03-17, Control # 228-03 1-29
16000 SERVICE/MAINTENANCE MANUAL INTRODUCTION
BOOM/MAST HOIST SYSTEM OPERATION
See Figure 1-17, Figure 1-18, and Figure 1-19.
The boom/mast hoist (drum 4) is mounted at the rear of the
rotating bed and controls the boom when the crane is
configured as a liftcrane. The boom hoist (drum 5) is
mounted in the mast butt and controls the boom when the
crane is configured with a with an optional MAX-ER
attachment. Only one of these drums can be operated at a
time, as the same pump operates both drums. The boom/
mast hoist (drum 4) operation is described in this section;
boom hoist (drum 5) is similar.
One hydraulic pump drives two separate motor gearboxes
on each end of hoist drum. The right track pump can also
power drum 4 through a diverting valve in the setup
configuration. The hoist drum is controlled with the control
handle movement and node controllers. The control handle
is inoperable when the park brake is applied.
In the liftcrane configuration the boom/mast hoist (drum 4) is
controlled with the control handle on left side console. In the
luffing jib configuration the boom/mast hoist is controlled with
the control handle on far right of the right side console, while
the luffing jib hoist is controlled by the control handle on the
left side console.
Hydraulic charge pressure from the system charge pump
supplies hydraulic make-up fluid to the low-pressure side of
each boom/mast hoist motor. A pressure sender in the high-
pressure side of the boom/mast hoist system provides
pressure information to the Node-1 controller. The low-side
pressure supplies the hydraulic pilot pressure to operate the
motor servos. A fixed orifice between pump ports A and B
allows for smoother drum operation.
When the boom/mast hoist motors rotate, a speed sensor
mounted at one motor monitors the rotor movement and
sends an input voltage to the Node-1 controller. The Node-2
controller sends a 24 volt output to the rotation indicator in
the control handle. As the boom/mast hoist drum rotates
faster, the rotation indicator on top of the control handle
pulsates with a varying frequency to indicate the drum
rotational speed. The handle command in percent from
neutral is shown on the Diagnostic Screen.
Continuous changing of closed-loop fluid occurs through
leakage in the pump, motor, and external sequence/flow
valve. The sequence/flow valve opens at 14 bar (203 psi)
and removes 15 Lpm (4 gpm) of hot fluid from the system by
dumping the fluid into the motor case where the fluid returns
to the tank.
Boom/Mast Hoist Brake and Pawl
Hydraulic pressure to operate the hoist brake is from the low-
pressure side of the system. Hydraulic pressure to operate
the drum pawl is output pressure from the accessory/MAX-
ER pump at 28 to 35 bar (406 to 508 psi).
When the boom/mast hoist brake switch is in the ON-park
position, the hoist brake release solenoid HS-10 (drum 4) or
HS-30 (drum 5) is disabled to apply the brake to drum. The
hoist pawl in solenoid HS-11 (drum 4) or (drum 5) HS-31 is
enabled to keep pawl applied to the drum flange. The hoist
pump does not stroke in response to control handle
movement.
When the hoist brake switch is in the OFF-park position, the
Node-5 controller sends a zero volt output signal to the pawl
in solenoid HS-11 and a 24 volt output to enable the pawl out
solenoid HS-12 in the pawl out direction. The brake remains
applied to drum until the Node-3 controller sends a 24 volt
output to brake solenoid HS-10 to release the brake. The
boom system circuit is active, waiting for a control handle
command.
Raising Boom
See Figure 1-17 and Figure 1-19.
When the boom/mast hoist control handle is moved back for
booming up, an input voltage of 2.4 volts or less is sent to the
Node-1 controller. The Node-3 controller sends a variable
zero to 24 volt output that is divided by a resistor and applied
to the pump EDC. The Node-4 and 5 controllers send a
variable zero to 24 volt output that is divided by a resistor and
applied to each hoist motor PCP. The Node-1 controller
checks that the boom up limit switch is closed and no
hydraulic system fault is present.
The pump EDC tilts the swashplate in the up direction to
satisfy the pressure memory. The Node-1 controller
compares boom 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 the
brake release solenoid HS-10. The brake solenoid shifts to
block the drain port and opens the port to the low-pressure
side of system to release the drum 4 brake.
FIGURE 1-17
HS-10
HS-12
HS-11
HS-13
HS-14
Brake
Pawl
Diverting
Valve
Pressure
Sender
Pump
(EDC)
16-1012
Accessory Pump
(Low-Pressure)
Accessory Pump
(Low-Pressure)
Motor
(PCP)
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