Manitowoc MLC650, Service Maintenance Manual

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Reference
Only
Manitowoc
Published 09-09-16, Control # 229-09
10-21
MLC650 SERVICE/MAINTENANCE MANUAL ACCESSORIES
10
10
Manual Control
NOTE: Manual control is used only for troubleshooting the
rigging winch and is not used for normal operation.
Spool In Using Manual Control
See Figure 10-18 for the following.
When the manual control lever for the rigging winch (6,
Figure 10-8 ) on the upperworks jacking and rigging winch
valve assembly is moved to the spool-in position (9,
Figure 10-8 ), the corresponding valve spool moves to a
position that allows hydraulic fluid from the accessory pump
to flow through the function check valve (6) and a check
valve in the counterbalance valve (7). The hydraulic fluid
then flows to the spool-in/raise side (5) of the motor. At the
same time, the hydraulic fluid flows through the brake shuttle
valve (2) to the drum brake (4), releasing the brakes. From
the opposite side of the motor, the hydraulic fluid returns to
the tank.
Spool Out Using Manual Control
See Figure 10-18 for the following.
When the manual control lever for the rigging winch (6,
Figure 10-8 ) on the upperworks jacking and rigging winch
valve assembly is moved to the spool-out position (11,
Figure 10-8 ), the corresponding valve spool moves to a
position that allows hydraulic fluid from the accessory pump
to flow to the spool-out/lower side (3) of the motor. It also
provides pilot pressure to the counterbalance valve (7),
causing it to shift to a position that forces the return hydraulic
fluid from the opposite side of the motor to flow through an
orifice passage as it flows back to the tank. The orifice
creates some back pressure to prevent uncontrolled motor
speed during spool out.
At the same time, the hydraulic fluid from the accessory
pump flows through the brake shuttle valve (2) to the drum
brake (4), releasing the brakes.