Manitowoc MLC650, Service Maintenance Manual

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Reference
Only
ACCESSORIES MLC650 SERVICE/MAINTENANCE MANUAL
10-10
Published 09-09-16, Control # 229-09
Manual Control
Extend Jack Cylinder Using Manual Control
NOTE: Manual control is only used for troubleshooting the
rotating bed jacks.
When a manual control lever (1, Figure 10-8 ) on the
upperworks jacking and rigging winch valve assembly is
moved to the extend position (9,
Figure 10-8 ), the
corresponding valve spool moves to a position that allows
hydraulic fluid from the accessory pump to flow to the
corresponding jack cylinder counterbalance valve (2,
Figure 10-11 ).
Within the counterbalance valves, flow and control is as
follows:
• The rod side counterbalance valve is piloted open by the
rod side pressure and the accessory pressure from the
valve spool on the extend side. Once open, the oil on the
rod side is allowed to exit the cylinder and return to tank.
• The piston side counterbalance valve has an integral
bypass check valve that allows the accessory pressure
to enter the piston side of the cylinder, extending the
cylinder.
Retract Jack Cylinder Using Manual Control
NOTE: Manual control is only used for troubleshooting the
rotating bed jacks.
When a manual control lever (1, Figure 10-8 ) on the
upperworks jacking and rigging winch valve assembly is
moved to the retract 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
corresponding jack cylinder counterbalance valve (2,
Figure 10-11 ).
Within the counterbalance valves, flow and control is as
follows:
• The piston side counterbalance valve is piloted open by
the piston side pressure and the accessory pressure
from the valve spool on the retract side. Once open, the
oil on the piston side is allowed to exit the cylinder and
return to tank.
• The rod side counterbalance valve has an integral
bypass check valve that allows the accessory pressure
to enter the rod of the cylinder, retracting the cylinder.