![Manitowoc Grove YB5515-2 Service And Maintenance Manual Download Page 71](http://html.mh-extra.com/html/manitowoc/grove-yb5515-2/grove-yb5515-2_service-and-maintenance-manual_701236071.webp)
HYDRAULIC SYSTEM
CD5515-2/YB5515-2 SERVICE MANUAL
4-10
Published 1-20-2017, Control# 483-02
housing. The housing rotates with the mast and the shaft is
stationary.
Functions
The numbers of each port is stamped on the housing and on
the lower end of the shaft.
Port No. 1
Hydraulic oil under pressure flows through this port when the
hoist block is being raised. When lowering the hoist block the
hydraulic oil under low pressure flows through this port.
Port No. 2
Hydraulic oil under pressure flows through this port when the
hoist block is being lowered. When raising the hoist block the
hydraulic oil under low pressure flows through this port.
Port No. 3
Hydraulic oil under pressure flows through this port when the
boom is being lowered. When raising the boom the hydraulic
oil under low pressure flows through this port.
Port No. 4
Hydraulic oil under pressure flows through this port when the
boom is being raised. When lowering the boom the hydraulic
oil under low pressure flows through this port.
Port No. 5
Hydraulic oil under pressure flows through this port when the
boom is being retracted. When extending the boom the
hydraulic oil under low pressure flows through this port.
Port No. 6
Hydraulic oil under pressure flows through this port when the
boom is being extended. When retracting the boom the
hydraulic oil under low pressure flows through this port.
Port No. 7
Hydraulic oil under low pressure flows through this port from
the hoist motor drain.
Troubleshooting
Leakage between the passages of the hydraulic swivel will
cause loss of power or possible wrong operation of one of
the circuits. It is important to know the arrangement of the
passages in the hydraulic swivel. Remember that the oil will
always follow the path of least resistance.
LIFT CIRCUIT
Use the hydraulic schematic in Section 12 along with the
following text to understand how the lift circuit functions.
General
The lift hydraulic circuit includes two lift cylinders, two holding
valves, Ports 3 and 4 in the hydraulic swivel, an anti-double
FIGURE 4-3
a0466
Hydraulic Swivel Port Arrangement, Typical
Reference Only