Manitowoc 999 Service And Maintenance Manual page 41

999 SERVICE/MAINTENANCE MANUAL
999CSM1-118
+
F15
5A
5D
10A
CB7
K1
8
50 AMP
OFF
RAISE
LOWER
3
1
RAISE
F4
8 8D
5A
F8
8T
8
5A
F4
8 8D
5A
The PC controls lowering speed by varying the voltage to
pump EDC and motor PCP in relation to handle movement.
As front drum handle is pushed forward, 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.
The load weight attempts to drive motor faster than return
fluid can return to low-pressure side of pump. System charge
pump maintains fluid supply at a positive pressure to motor.
Manitowoc
ENGINE
RUN
STOP
STOP
5DA
F12
REGULATED 10V DC OUTPUT
3A
FRONT DRUM
OFF
LOWER
REAR DRUM
3
3 2 14
BLOCK UP LIMITS
DIGITAL DISPLAY
UP SCROLL
DOWN SCROLL
CRANE MODE
CONFIRM
SELECT
SEAT SWITCH
FRONT DRUM
PRESSURE TRANSDUCER
6 3
REAR DRUM
PRESSURE TRANSDUCER
FRONT DRUM
D A
SHAFT
SPEED
F B
ENCODER
3 8
REAR DRUM
D A
SHAFT
SPEED
F B
ENCODER
Published 05-16-17, Control # 233-03
START
3
7
MS1
8P1
0
WA-01
25
WA-03
25A
WA-04
FRONT DRUM
RIN
WC-05
PUMP CONTROL
WD-19
REAR DRUM
WD-18 WC-06 PUMP CONTROL
WB-26
MOTOR CONTROL
WD-24
WB-33
PROGRAMMABLE
CONTROLLER WD-25
WB-09
WD-27 ROTATION INDICATOR
WB-10
WD-28
WB-34
WD-32 FRONT DRUM PAWL IN
WA-22
WD-33
WA-23 WD-34 REAR DRUM PAWL IN
WD-35
WD-01
WC-18
WD-02
WD-08
WD-03
WC-19
WD-04
WD-09
Pump swashplate position restricts returning fluid flow.
Pressure builds on fluid return side of closed-loop, acting as
a motor brake to control lowering speed.
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 flow output. The PC also shifts
the motor back to maximum displacement for slower output
speed to slow the drum rotation. The PC shifts the pump
swashplate through neutral until the EDC has a slightly
positive signal. This shifts the swashplate in the positive
direction and builds pressure on high-pressure side of
closed-loop. The PC stores load-holding pressure in
pressure memory. After control handle neutral switch opens,
the PC sends an output signal to disable brake release
INTRODUCTION
_
K1
0
SYSTEM FAULT
BUZZER
OPERATING LIMIT
BEEPER
B A
12
EDC
B A
EDC
FRONT DRUM
FD
13 3
PCP
REAR DRUM
MOTOR CONTROL
RD
PCP
FRONT DRUM
3
REAR DRUM
ROTATION INDICATOR
HS
19
FRONT DRUM
PAWL OUT
HS
20
HS
24
REAR DRUM
PAWL OUT HS
25
10 3
FRONT DRUM
BRAKE
HS
16
11 3
REAR DRUM
BRAKE HS
21
FIGURE 1-19
1
3
9
1-29