Manitowoc 2250 Service And Maintenance Manual

Reference Only
Manitowoc Published 11-06-15, Control # 040-13 1-53
2250 SERVICE/MAINTENANCE MANUAL INTRODUCTION
1
Load Drum System — Free Fall
General
See Figure 1-31 and Figure 1-32 for the following procedure.
In Free Fall mode the load can be lowered with control
handle (Standard mode) or working brake pedal (Free Fall
mode). Depending on crane load drum configuration, the left
load drum working brake pedal on the cab floor normally
operates either full front drum (Drum 1) or right-rear drum
(Drum 2), while the right load drum working brake pedal on
the cab floor normally operates either full rear (Drum 2) or
left-rear drum (Drum 3).
The PC will not allow a drum to be switched to Free Fall
mode until the following steps are performed:
• Apply and latch working brake pedal for the drum being
used.
• For right-rear drum operation, place the load drum
selector switch in right-rear (Drum 2) position.
• Select DRUM 2 FFALL on crane mode switch then turn
switch to confirm position.
• Turn Drum 2 park brake switch to off.
When selected load drum control handle is at off position,
load drum pumps do not stroke. If the selected load drum
control handle is in off position when charge pressure is lost,
the PC applies selected drum brake, but clutch remains
released from drum shaft.
If a low charge pressure fault occurs while hoisting or power
lowering, load drum pumps de-stroke. The PC sends an
output signal that applies clutch to the drum and applies the
selected drum brake. Apply and latch working brake pedal
before moving load drum control handle to off.
Load Drum Hoisting — Free Fall
The following description is for hoisting right-rear load drum
(Drum 2) while operating in the Free Fall mode. Free fall
hoisting of the other load drums is the same, except for
different drum, brake, clutch, and working brake pedal.
The procedure for hoisting in Free Fall mode is the same as
in Standard mode. The selected free fall drum clutch is
engaged and brake is released by the PC. See Load Drum
Hoisting topic in previous section.
When control handle is moved to off, the selected load drum
brake remains released from drum. The PC sends a 12 volt
output signal to right-rear drum clutch solenoid AS-10 to
release the drum clutch. This applies air pressure to cylinder
of right-rear drum clutch to release from drum shaft, returning
drum to Free Fall mode. The load will fall uncontrolled if
working brake pedal is not applied before moving
control handle to off!
Load Drum Lowering — Free Fall
The following description is for lowering right-rear load drum
(Drum 2) while operating in the Free Fall mode. Free fall
lowering of the other load drums is the same, except for
different drum, brake, clutch, and working brake pedal.
In Free Fall mode if a selected load drum control handle is
moved in either direction from off, the PC sends an output
signal to right-rear drum clutch solenoid AS-10. This
exhausts air pressure from selected drum clutch cylinder.
Clutch spring-applies to connect drum shaft to motor. The
load is then controlled in full power in the direction the
handle was moved.
When working brake pedal is applied, full manifold air
pressure closes free fall safety pressure switch, sending an
input signal to the PC that allows free fall operation.
WARNING
Falling Load Hazard!
When operating in Free Fall mode, load will lower
uncontrolled if drum brake is not applied with working
brake pedal when control handle is moved to off.
Be ready to apply load drum working brake pedal so
lowering speed can be controlled and load can be
stopped immediately, when necessary.
WARNING
Dropping Load Hazard!
Begin moving selected load drum handle to off before
releasing working brake pedal to hold load while clutch
releases from drum shaft.
Hoisted load will drop momentarily if working brake pedal
is not applied!
CAUTION
Clutch/Motor Hazard!
Do not move a load drum control handle in either direction
from off while a load is free falling. Damage to clutch and/
or motor drive system could occur. Stop the load with
working brake pedal before moving a load drum control
handle in either direction.
Do not turn Free Fall mode off or turn on drum brake while
a load is free falling. Stop loads with working brake pedal,
then turn Free Fall mode off or turn on drum brake.

Manitowoc 2250 Specifications

General

Brand	Manitowoc
Model	2250
Category	Construction Equipment
Language	English