Manitowoc 999 Service And Maintenance Manual

Reference Only
Manitowoc Published 05-16-17, Control # 233-03 1-27
999 SERVICE/MAINTENANCE MANUAL INTRODUCTION
1
A high speed option is available for front/rear drums. This
option allows increased fluid to two motors on tandem drive
shafts for driving the drum. Electrical control of motors is
similar to standard configuration.
Load Drum Brake and Pawl Switch
When selected front drum (10) or rear drum (11) brake switch
is in on - park position, front drum hoist brake release
solenoid HS-16 or rear drum hoist brake release solenoid
HS-21is disabled so brake is spring-applied to drum. Front
drum pawl in solenoid HS-19 or rear drum pawl in solenoid
HS-24 is enabled and pawl is engaged. Selected load pump
does not stroke in response to control handle movement.
When selected front drum or rear drum brake switch is
placed in off - park position, front and rear drum brakes
remain spring-applied to selected load drum until the PC
releases the brake. The PC sends an output signal to enable
front drum pawl out solenoid HS-20 or rear drum pawl out
solenoid HS-25. The pawl is disengaged from drum. Load
drum control handle circuit to PC remains open.
Load Drum Hoisting
See Figures 1-17 and 1-18
The following description of operation is for front drum while
operating in full power. Operation of other load drums is the
same, except for different drum, brake, and pawl.
When front drum handle (1) is moved back for drum hoist,
handle neutral switch closes, sending an input voltage of 5
volts or more to PC. The PC sends a positive output voltage
to front drum pump EDC (12) and a positive output voltage to
motor PCP (13). The PC checks that front drum block-up
limit switches (14) are closed with no hydraulic system faults
present.
The PC requires that front drum pump strokes in hoist
direction to satisfy pressure memory. The PC compares front
drum holding pressure to value stored in pressure memory.
When system pressure is high enough, the PC sends a
positive output signal to enable brake release solenoid HS-
16. Brake release solenoid HS-16 shifts, to block tank port
and open port from low-pressure side of closed-loop system
to release front drum spring brake.
The PC sends a positive output voltage to enable front drum
pump EDC that tilts pump swashplate to stroke pump in the
hoist direction. Hydraulic fluid flows from front drum pump
port A to port A of front drum motor. Fluid from motor port B
returns to front drum pump port B.
The PC controls raising speed by varying the voltage to
pump EDC and motor PCP in relation to handle movement.
As front drum handle is moved back, the PC sends a signal
to increase the front drum pump swashplate angle. The PC
also sends a signal to reduce the displacement of the motor.
The PC is continuously balancing the system pressure and
the motor displacement angle so the motor displacement
goes to minimum when handle is all the way back, if the
torque on the motor is not too high. Knowing the
displacement of the motor, the PC may then control the
speed that the motor turns by regulating the flow through the
pump.
When front drum handle is moved to neutral position, the PC
sends an output signal to front drum pump EDC to decrease
swashplate angle, reducing oil flow output. This shifts the
motor back to maximum displacement for slower output
speed to slow the drum rotation. The PC stores the load
holding pressure in pressure memory. After control handle
neutral switch opens, the PC sends an output signal to
disable brake release solenoid HS-16 to spring-apply brake
before load pump de-strokes.

Manitowoc 999 Specifications

General

Brand	Manitowoc
Model	999
Category	Construction Equipment
Language	English