Manitowoc
Published 03-21-2021, Control # 264-01
5-23
MLC150-1 SERVICE/MAINTENANCE MANUAL
HOISTS
5
DRUM 4 PAWL
Operation
The pawl is controlled by the Drum 4 park switch in the
operator cab. See Section 3 of the Crane Operator Manual.
Drum 4 Parked
See View A—Engaged.
The hydraulic cylinder (1) extends and rotates the cam (2)
away from the pawl (3). This allows the spring (4) to rotate
the pawl into engagement with the drum ratchet (7).
Drum 4 Un-Parked
See View B—Disengaged.
The hydraulic cylinder (1) retracts and rotates the cam (2)
against the pawl (3). This action rotates the pawl out of
engagement with the drum ratchet (7). It may be necessary
to operate the drum slightly in the raise direction to fully
disengage the pawl from the ratchet.
Maintenance
Daily
Visually check the pawl for proper operation as described
under Operation.
Weekly
Apply open gear lube to the sliding surfaces between the
cam (2) and pawl (3).
Spring Adjustment
If the spring tension becomes insufficient, perform the
following.
1.
Visually check the position of the pawl and make sure it
is fully engaged with the ratchet.
If the pawl is not fully engaged, perform the following.
a.
Start the engine and operate the drum slightly in the
up direction.
b.
Check the pawl again and make sure it is fully
engaged with the ratchet.
NOTE:
In some cases, the pawl may come to rest on the
top of a ratchet tooth. There must be enough spring
tension to pull the pawl into the root of a ratchet
tooth if the drum starts to turn in the down direction.
2.
Stop the engine and lockout-tagout the ignition switch.
3.
Adjust the eye bolt (6) adjusting nuts (5) so there is
enough spring (4) tension to engage the pawl.
4.
When new at the factory, the spring is adjusted to
Dimension B
5.
Start the engine and check the pawl for proper operation
and engagement.
Limit Switch Head Orientation
If a new limit switch is being installed, orient the head (8B,
View D) as follows:
1.
Remove the screws (8A).
2.
Rotate the head (8B) 90° counterclockwise.
3.
Install and securely tighten the screws (8A).
4.
Install the lever (11).
Limit Switch Adjustment
The limit switch (8) signals the crane’s control system when
the Drum 4 pawl is fully disengaged.
1.
Disengage the pawl by moving the Drum 4 park switch
to the UN-PARK position. It may be necessary to boom
up slightly before the pawl will disengage the ratchet.
2.
Stop the engine and lockout-tagout the ignition switch.
3.
Loosen the setscrew (9) so the limit switch lever (11) is
free to rotate on the limit switch shaft (10).
4.
Rotate the limit switch lever up and hold it so the roller is
against the pawl (3).
5.
Turn the limit switch shaft counterclockwise until the limit
switch clicks open and hold.
6.
Make sure the roller is against the actuator plate on the
pawl (3) and tighten the setscrew to lock the adjustment.
7.
Start the engine and check for proper operation:
•
Engage the pawl by moving the Drum 4
park switch to the PARK position and
try to boom down. The drum should not
operate in the down direction. The fault
alert should come on and the pawl
engaged fault icon should appear in the fault bar of
the Main Display Working Screen.
•
Disengage the pawl by moving the Drum 4 park
switch to the UN-PARK position and try to boom
down. The drum should operate in the down
direction.
8.
Readjust the limit switch if required.
WARNING
Falling Boom Hazard
Before performing the following steps, 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.
REFERENCE
ONLY
Summary of Contents for MLC150-1
Page 1: ...Service Maintenance Manual Manitowoc MLC150 1 R E F E R E N C E O N L Y ...
Page 2: ...R E F E R E N C E O N L Y ...
Page 4: ...THE ORIGINAL LANGUAGE OF THIS PUBLICATION IS ENGLISH R E F E R E N C E O N L Y ...
Page 205: ...R E F E R E N C E O N L Y ...
Page 206: ...R E F E R E N C E O N L Y ...
