Only
HOISTS
MLC650 SERVICE/MAINTENANCE MANUAL
5-28
Published 09-09-16, Control # 229-09
Drum 4 Pawl Operation
.
The pawl is controlled by the park switch.
When the drum park is turned on to engage the drum pawl,
the IOLC32 control module sends a 24 V
DC
output to the
drum 4 pawl-in solenoid valve, energizing the solenoid. The
solenoid valve shifts position to route hydraulic fluid from the
accessory pump 9 to the rod end of the pawl cylinder. The
cylinder rod retracts, moving the drum pawl to the engaged
position.
When the drum park is turned off to disengage the drum
pawl, the IOLC32 control module sends a 24 V
DC
output to
the drum 4 pawl-out solenoid valve, energizing the solenoid.
The solenoid valve shifts position to route hydraulic fluid from
the accessory pump 9 to the tube end of the pawl cylinder.
The cylinder rod extends, moving the drum pawl to the
disengaged position.
When the control system is not powered, the drum pawl
solenoid valve moves to the center position, allowing
hydraulic fluid at both ends of the pawl cylinder to return to
the tank. Spring force holds the pawl in the engaged position.
Drum 4 Pawl Limit Switch
for the following procedures.
Limit Switch Replacement
Field adjustment should not be necessary unless a new limit
switch is installed.
Removal
1.
Land the load from the drum being adjusted.
2.
Lockout-tagout the crane.
3.
Remove the screws (5) and the limit switch (1).
4.
Remove the limit switch cover (7).
5.
Disconnect the electrical wires, including the jumper
wire, inside the limit switch (see View C).
6.
Remove the cable restraint connector (6) and carefully
pull the electrical cable and wires from the limit switch.
7.
Loosen the screws (10) and remove the limit switch arm
(2) from the limit switch shaft (11).
Installation
1.
Connect the electrical wires to the new limit switch as
follows.
a.
Remove the limit switch cover (7).
b.
Connect the wires, including the jumper wire, to the
correct terminals in the limit switch (see View C).
c.
Install and tighten the cable restraint connector (6)
to the limit switch (1).
d.
Install the limit switch cover.
2.
If needed, reposition the limit switch head as follows.
a.
Remove the screws (8).
b.
Rotate the limit switch head (9), as necessary.
c.
Install the screws (8).
3.
Install the limit switch arm (2) onto the limit switch shaft
(11). Do not tighten the screw (10) at this time (see View
B).
4.
Using the screws (5), install the limit switch (1).
Adjustment
1.
Slowly turn the limit switch shaft (11) clockwise (as
viewed from shaft end) until the limit switch clicks open,
then hold the shaft.
2.
Adjust the limit switch arm (2) 5° from horizontal position
(see View A).
3.
Adjust the limit switch position so that it trips when the
pawl is fully disengaged from the drum.
4.
Tighten the screw (10) to secure the limit switch arm (2)
to the limit switch shaft (11) and lock adjustment.
WARNING
Falling Boom Hazard!
Avoid possible injury. Before performing the steps in this
section, land the loads and lower the boom onto blocking
at ground level. There is no positive means of holding the
boom up when the pawl is being serviced.
WARNING
Falling Boom Hazard!
Avoid possible injury. Before performing the steps in this
section, land the loads and lower the boom onto blocking
at ground level. There is no positive means of holding the
boom up when the pawl is being serviced.
Summary of Contents for MLC650
Page 1: ...R e f e r e n c e O n l y Service Maintenance Manual Manitowoc MLC650 ...
Page 2: ...R e f e r e n c e O n l y ...
Page 4: ...R e f e r e n c e O n l y THE ORIGINAL LANGUAGE OF THIS PUBLICATION IS ENGLISH ...
Page 375: ...R e f e r e n c e O n l y ...
Page 376: ...R e f e r e n c e O n l y ...
