Manitowoc 2250 Service Maintenance Manual

Reference Only
INTRODUCTION 2250 SERVICE/MAINTENANCE MANUAL
1-36
Published 07-19-16, Control # 249-01
which clutches are released, depending on the control
handle command and the mode selected.
Drum Pawls
A selected drum pawl must be disengaged before the drum
can operate. Components for the engage/disengage
operation for a selected drum pawl are specific to the drum
pawl system being operated. A ratchet and pawl latch
provides a positive way of locking the boom hoist, luffing
hoist, front drum, rear drum, and auxiliary drum (if equipped).
Pawl operation is controlled with selected drum brake switch.
If a pawl is engaged during hoisting up, a hoist operating
drive fault occurs when stopped because the PC cannot
command down against the pawl to prove the brake is
applied.
If a pawl switch is engaged accidentally when hoisting down,
the PC sends an output signal to enable that drum brake. For
the boom hoist pawl and luffing jib drum pawl, the spring
applied brake on the motor end of the drum shaft enables
and the pump de-strokes to stop the function. The PC delays
the engage signal to the pawl engage air solenoid so the
pawl does not engage for approximately 10 seconds after the
hoist stops. The load drum pawls respond similarly, but the
front and rear load drum brakes are spring applied and air
released.
Swing System Operation
General
See Figure 1-20 and Figure 1-21 for the following.
One hydraulic swing pump drives one swing motor (optional
swing drive has one swing pump driving two swing motors).
The swing system is controlled with swing control handle
movement and the programmable controller (PC). The swing
control handle is inoperable when the swing brake is applied.
The motor driven swing gearbox drives a tooth gear that is
meshed with the undercarriage turntable bearing to swing
the rotating bed.
The swing motor is controlled directly by the output fluid
volume of the swing pump. The PC does not control the fixed
displacement swing motor. Swing pressure senders monitor
the pressure on the swing left and the swing right sides of the
swing closed-loop system. If there is low swing pressure or if
either pressure sender fails, swing movement may be
erratic.
The rotating bed is free to coast if the swing control handle is
in the neutral position and if the swing brake is released.
When the swing control handle is moved from the OFF
position, an input signal is sent to the PC. The PC sends a
12 V output signal to enable the optional swing/travel alarm.
When the swing control handle is moved to the OFF position,
the PC sends a 0 V output signal to disable the swing/travel
alarm.
An orifice across the swing pump and motor ports A and B
allow smoother fluid flow when shifting the swing from one
direction to the other.
Swing speed and swing torque can be selected for the type
of work being performed by referring to Speeds screen in
Troubleshooting
Section 10.
Swing Brake and Swing Holding Brake
The swing system has a spring-applied hydraulically
released brake on the drive shaft.
Pilot charge pressure from the boom hoist charge pump
must be about 17 bar (250 psi) for full release of the swing
brake. If system charge pressure is below 13 bar (190 psi),
the swing brake could be partially applied and could damage
the swing system. If brake pressure or electrical power is lost
when operating, the swing brake is applied.
When the swing brake switch is in the OFF position, an input
voltage is sent to enable the swing brake solenoid valve HS-
7. The swing brake solenoid valve shifts to block the tank
port and opens the port to supply hydraulic fluid to release
the swing brake from the shaft.
When the swing brake switch is placed in the ON position, an
input voltage is sent to disable the swing brake solenoid
valve HS-7. The brake solenoid valve shifts to close the fluid
flow to the brake and opens the tank port to apply the brake.
The swing holding brake switch is located on the side of the
swing control handle. To prevent damage to the swing
system, the swing holding brake switch must only be applied
when the crane is at a standstill.
When the holding brake switch is pressed in and held, an
input voltage is sent to disable the shift swing brake solenoid
HS-7. The swing brake valve shifts to block the fluid to the
brake, and the swing brake is applied.
When the swing holding brake switch is released, an input
voltage is sent to enable the swing brake solenoid HS-7. The
swing brake valve shifts, allowing system pressure to
hydraulically release the brake.
Swing Right or Left
When the swing control handle is moved to the left, an input
voltage of 5 V or more is sent to the PC. The PC sends a
variable plus 0 to 2.8 V output that is applied to the swing
pump’s electronic displacement control (EDC). The pump’s
EDC tilts the swashplate relative to the control handle’s
movement. Fluid flows from the pump ports to the motor
ports, turning the rotating bed to the left.
When the swing control handle is moved to the right, an input
voltage of 5 V or less is sent to the PC. The PC sends a
variable minus 0 to 2.8 V output that is applied to the swing
pump’s EDC. The pump’s EDC tilts the swashplate relative
to the control handle’s movement. Fluid flows from the pump
ports to the motor ports, turning the rotating bed to the right.

Manitowoc 2250 Specifications

General

Brand	Manitowoc
Model	2250
Category	Construction Equipment
Language	English